saving a national icon: preliminary estimation of the ......suzie greenhalgh portfolio leader -...

Saving a national icon:

Preliminary estimation of the additional cost of achieving kiwi population stability or 2% growth

Saving a national icon: Preliminary estimation of the additional cost of achieving kiwi population stability or 2% growth

John Innes1, Florian V. Eppink2

Landcare Research

Hugh Robertson3

Department of Conservation

Prepared for:

Kiwis for kiwi / The Kiwi Trust

Private Bag 68908 Auckland 1145

July 2015

1Landcare Research, Gate 10 Silverdale Road, University of Waikato Campus, Private Bag 3127, Hamilton 3240, New Zealand, Ph +64 7 859 3700, Fax +64 7 859 3701, www.landcareresearch.co.nz

2Landcare Research, 231 Morrin Road, St Johns, Private Bag 92170, Auckland 1142, New Zealand, Ph +64 9 574 4100, Fax +64 9 574 4101

3Department of Conservation, P.O. Box 10420, Wellington 6143, New Zealand

http://www.landcareresearch.co.nz/

Reviewed by: Approved for release by:

Roger Pech Scientist Landcare Research

Suzie Greenhalgh Portfolio Leader - Enhancing Policy Development Landcare Research

Landcare Research Contract Report: LC2136

Disclaimer

This report has been prepared by Landcare Research for Kiwis for kiwi. If used by other parties, no warranty or representation is given as to its accuracy and no liability is accepted for loss or damage arising directly or indirectly from reliance on the information in it.

Landcare Research Page iii

Contents

Executive summary ..................................................................................................................... v

Glossary of key terms ................................................................................................................. vi

Summary ................................................................................................................................... vii

1 Introduction ....................................................................................................................... 1

2 Background ........................................................................................................................ 2

3 Objectives .......................................................................................................................... 2

4 Modelling kiwi recovery strategies ................................................................................... 2

4.1 Overview .............................................................................................................................. 2

4.2 Kiwi taxa and estimated 2015 population sizes .................................................................. 3

4.3 Current kiwi threats and management regimes, and resultant estimated population

growth rates ........................................................................................................................ 5

4.4 Modelling halting the decline and achieving 2% per annum growth ................................ 14

5 Estimating current and additional cost ........................................................................... 19

5.1 Cost data considerations ................................................................................................... 19

5.2 Annual cost of current management ................................................................................ 22

5.3 Additional cost of population stability and growth targets .............................................. 23

6 Discussion ........................................................................................................................ 31

6.1 Adequacy of input kiwi data .............................................................................................. 33

6.2 Kiwi modelling assumptions .............................................................................................. 33

6.3 Selecting growth scenarios and preferred management techniques ............................... 33

6.4 Community conservation and cost modelling ................................................................... 34

6.5 Additional funding required to halt declines and achieve 2% growth p.a. ....................... 35

6.6 Priority research and monitoring ...................................................................................... 36

7 Acknowledgements ......................................................................................................... 36

8 References ....................................................................................................................... 37


Page iv Landcare Research

Appendix 1: Explanation of key terms in this report ............................................................... 40

Appendix 2: Cost data and assumptions .................................................................................. 42

Landcare Research Page v

Executive summary

Kiwi conservation has been very successful since the Kiwi Recovery Programme was

launched in 1991. Much has been learned about kiwi and their threats; some tools have been

developed to grow kiwi populations; there is a groundswell of community and political

support to keep kiwi safe, and populations of the four rarest kiwi taxa are increasing.

However, substantial additional effort is required to reverse the overall potential decline of

2% per annum (without management) into a 2% increase across all 10 taxa (‘kinds’ of kiwi).

With the assumptions that kiwi conservation projects run by community groups ($6.3 million

of funded and donated costs) and by the Department of Conservation (DOC) remain at

current levels, and with new government funding of $6.8 million per year from 2018 onwards

as announced in Budget 2015, we estimate that all 10 kiwi taxa can be at least maintained at

current population levels. By our best modelled estimates, a further ca $1.3 million per year is

required across all kiwi to achieve an average of 2% per annum growth per year between now

and 2030. Using DOC staff instead of community volunteers, more aerial poisoning, and

allocating pest-fence costs to kiwi recovery will increase the estimated funding need.

Nationally, major challenges ahead include: a) reversing declines of those more abundant, but

steadily declining, kiwi taxa that live in remote and rugged parts of the South and Stewart

Islands, where human populations are small and remote from kiwi populations, and b) cost-

effectively monitoring the outcomes of management for all kiwi.


Page vi Landcare Research

Glossary of key terms

Kiwi taxa (plural) and taxon (singular): For simplicity, we refer to the 10 different

‘kinds’ of kiwi (e.g. little spotted, Northland brown) as taxa, even though some are not

taxonomically described in scientific literature.

Management regime: There are seven active management regimes, such as pest

trapping, aerial poisoning or Operation Nest Egg, that are applied to kiwi populations to

increase their numbers.

Population growth rates: Kiwi populations are subject to annual change, depending on

nett outcomes of births and immigration versus deaths and emigration. We express

change rates either as (for example) 2% p.a. (so that each year the population is 2%

larger), or for modelling purposes, as 1.02. There may also be 2% p.a. declines, which

we express for modelling as 0.98.

Modelling parameters: Population modelling in this report uses (for each taxon) an

initial population size and subsequent growth rates that may differ for each

management regime, but population size and growth rates are both imperfectly known.

Therefore, we model these possible errors by choosing between most likely, or high and

low (e.g. ±30%) values of modelling parameters.

Conservation scenarios: These are combinations of management regimes that in

aggregate achieve a desired population growth rate (e.g. 2%) target. All seven

management regimes can be mixed to create a large number of different conservation

scenarios, with different outcomes for the kiwi populations, and different costs.


Landcare Research Page vii

Summary

Client and Project

Kiwis for kiwi (The Kiwi Trust, K4K) asked Landcare Research to estimate the likely

cost of achieving 2% population growth of all 10 accepted and perceived taxa of kiwi,

given that unmanaged populations are estimated to be declining at 2% per annum.

Due to limited availability of input data, this project estimates the cost of the additional

(to current) management required to halt declines or increase populations at 2% per

annum for only the kiwi taxa not already meeting these targets. It does not estimate the

total cost of achieving 2% population growth for all 10 kiwi taxa.

Objectives

To determine additional management so that all 10 kiwi taxa will a) stop declining, or

b) increase by 2% per annum.

To estimate the costs of this additional management.

Methods

For all 10 kiwi taxa, we first estimated the 2015 population size, and then allocated all

individuals to one of seven management regimes, each with its own estimated annual

population change rate. We then estimated the resultant, nett change rate after 1 year

and after 15 years for each taxon’s population, considering all regimes.

For each taxon failing to achieve 0% or 2% growth under current management, we then

modelled increasing the number of kiwi subject to predator management, until the nett

change rate achieved the 0% or 2% target.

To incorporate possible errors with model parameters, we repeated this modelling with

maximum and minimum values for the initial (2015) estimated population size, and low

and high (± 30%) population growth rates under the different regimes.

K4K invited community groups to report on management and equipment costs used in

the previous year at their sites, particularly for trapping. We also obtained costs for

important predator-control regimes such as aerial 1080 that community groups do not

use, and for ONE.

Aggregating these reported costs enabled us to estimate the total cost of current kiwi

management for communities, but not for DOC. We distinguished between funded and

volunteered time and equipment to assess the size of financial resources donated by

community groups to the kiwi recovery programme.

We estimated the annual cost of the additional management required to halt declines or

achieve 2% per annum growth compared with the direct cost of current management.

These estimates assume that existing DOC and community expenditures for kiwi

conservation remain at their current levels.

We also show the temporally weighted sum of the annual costs over a 15-year period,

i.e. the present value of these costs, using standard discounting practice and a 10%

discount rate (i.e., the temporal weighting factor).


Page viii Landcare Research

Results

Under current management for 15 years using most likely population model

parameters, five kiwi taxa (little spotted, Northland brown, Coromandel brown, rowi

and Haast tokoeka) are estimated to increase at mean annual rates that already exceed

2% per annum. Eastern and western browns will increase but at <2% per annum. The

remaining three taxa are estimated to decline at varying mean annual rates: 1.0% for

Fiordland tokoeka, 1.6% for great spotted and 1.8% for Rakiura tokoeka. Selecting low

or high growth rate parameters for modelling changes these outcomes and

classifications in negative and positive directions respectively.

Where kiwi taxa do not already meet 0% or 2% targets, putting unmanaged birds into

one of the six regimes of active management can halt the decline of all 10 taxa, and

with most likely model parameters can also increase all 10 by mean 2% per annum

for the next 15 years. These statements remain true even with low growth rates for all

taxa except great spotted and Fiordland, for which 2% increase may be unattainable.

The current, total, annual, community expenditure (funded and donated) is around $6.3

million for the five kiwi taxa with substantial community involvement (Northland,

Coromandel, eastern, western, great spotted). This excludes Fiordland and Rakiura

tokoeka, for which we have no community-generated data, as well as Haast tokoeka,

rowi and little spotted which are managed primarily by DOC.

From their reporting, we conclude that community groups currently donate 44% of their

total costs, with 59% donated in the Coromandel. A large share of the donated costs is

for time volunteered for administration, trap-checking and advocacy.

The additional annual cost of management required to achieve population stability for

the taxa currently not achieving this (eastern, great spotted, Fiordland, Rakiura) is $1.7

– 3.9 million, depending on population parameters chosen. Using most likely

parameters, the additional annual cost is $2.6 million. The present value of the total cost

over a 15-year period is $18 – $38.5 million, depending on the chosen parameters,

conservation scenario, and using a 10% discount rate. The additional 15-year costs

using most likely parameters have a present value of $27.5 million.

The additional annual cost of achieving 2% population growth for the taxa not already

achieving this (eastern, western, great spotted, Fiordland, Rakiura) is $2.6 – $11.3

million, depending on the model parameter choices and management scenarios. Using

most likely parameters, the additional annual cost is $8.1 million. The present value of

these costs over a 15-year period is $22.5 – $102 million, depending on the chosen

modelling parameters, conservation scenario, and using a 10% discount rate. The

additional 15-year costs using most likely parameters have a present value of $73.5

million.

Conclusions

Significant additional funding is required to achieve either of the conservation targets.

With the scenarios we used, and assuming most likely model parameter choices,

on average funding of $2.6 million annually on top of current (2014/2015) funding

is needed for the next 15 years to halt kiwi declines. To achieve 2% growth of all

10 taxa, additional funding of $8.1 million annually is needed for the same period.


Landcare Research Page ix

Table Additional annual cost to achieve population stability or 2% growth for all 10 kiwi taxa, using most likely

population modelling parameters

Kiwi taxon Additional annual cost to achieve population stability

Additional annual cost to achieve 2% growth

Northland $0 $0

Coromandel $0 $0

Little spotted $0 $0

Haast $0 $0

Rowi $0 $0

Western (trapping scenario) $0 $90,000

Eastern (trapping scenario) $0 $322,000

Great spotted $1,500,000 $4,200,000

Fiordland $847,000 $2,900,000

Rakiura $250,000 $607,000

TOTAL $2,597,000 $8,119,000

The recently-announced funding package for kiwi conservation in Budget 2015 has an

injection of $11.2 million over the next 4 years. In the fourth year and thereafter, $6.8

million per annum will be available, which should allow stable populations to be

achieved. There would then be a shortfall of $1.3 million per annum to achieve 2%

growth across the board.

The investment commitment (present value) of the additional conservation effort

needed over a 15-year period to achieve kiwi population stability or 2% growth is

significant. As long as stoats and other threats to kiwi exist in significant numbers,

these costs will continue indefinitely. This suggests that research into more (cost)

effective predator control is likely to be a worthwhile investment.

Improved knowledge of sizes of current populations and their growth rates under

different management regimes for all 10 taxa, as well as improved quality of

community and other reported cost data on which this report rests, is required to refine

the predictions of this preliminary modelling. K4K and DOC both have roles to play in

developing improved technology and data, and in creating the conditions for these to be

shared and adopted by all kiwi conservation initiatives.

Landcare Research Page 1

1 Introduction

Kiwi collectively are an endemic bird family (Apterygidae) whose members were once found

throughout the main and large offshore islands of New Zealand, “probably originally in all

vegetated habitats” (OSNZ 2010). Currently there are 10 ‘kinds’ (actual or perceived taxa) of

kiwi, that in this report we refer to as ‘taxa’. Kiwi are taonga, and nationally iconic, birds.

New Zealanders perhaps connect more with kiwi than any other native animal because as

New Zealand nationals we call ourselves ‘kiwis’. However our small, flightless, feathered

namesakes have been struggling since various pest mammals were released, by design or by

mistake, into their environment. Predation of chicks and adults by stoats, ferrets, dogs and

cats has set kiwi populations throughout New Zealand on paths toward extinction.

By 2008, only ca 73 000 kiwi were best-guessed to remain, and unmanaged populations on

the mainland were estimated to be declining at 2–3% per annum (Holzapfel et al. 2008).

Currently, nine mainland kiwi taxa are deemed ‘threatened’ while the tenth – little spotted –

is recovering but only on pest-free offshore islands and in fenced mainland sanctuaries,

having been extirpated from its entire former mainland range (Robertson et al. 2013). It is not

just kiwi, moreover, that are at risk; other birds like kākā, kōkako, kākāriki, mōhua, whio,

kererū and kaki, as well as endemic lizards, frogs, invertebrates and freshwater fish are

declining due to predation and habitat destruction, disruption or pollution (Brown et al.

2015).

Past phases and outcomes of kiwi recovery management are described by Holzapfel et al.

(2008). The first kiwi recovery plan was published by the Department of Conservation in

1991 (Butler & McLennan 1991) and in the subsequent 24 years there has been enormous

progress with clarifying the taxonomic and trend status of populations, determining key

causes of decline, refining restoration tools; and enlisting the interest and involvement of

diverse community, corporate and government groups with kiwi conservation (Holzapfel et

al. 2008; Robertson & de Monchy 2012), although substantial uncertainties remain.

Major recovery tools have been: a) stoat- and other predator-trapping and poisoning at

various scales, including in ‘kiwi sanctuaries’; b) so-named ‘Operation Nest Egg’ (ONE) by

which eggs or chicks are removed from the wild and raised elsewhere until they can be

returned to the wild at a safe weight; and c) marooning populations on predator-free islands

and mainland ‘kohanga’ (nest or nursery). Most of these efforts have been and remain

successful in conserving kiwi populations at small (to ca 10 000 ha) and accessible sites

(Holzapfel et al. 2008; Robertson & de Monchy 2012). In the last 15 years, population

declines have been reversed for the rarest kiwi taxa, and reduced for others. The majority of

kiwi do not enjoy such intensive protection, however, and without pest management, many

populations continue to decline.

This report estimates the costs of the additional effort required to a) halt the decline of, or b)

increase by 2% per annum, all 10 actual or perceived kiwi taxa. This estimate will help guide

the strategy of Kiwis for kiwi (the Kiwi Trust; the key community partner of the kiwi

recovery programme) regarding how much money may need to be raised, and how and where

that funding should be invested.


Page 2 Landcare Research

2 Background

In November 2014, Kiwis for kiwi (hereafter K4K) commissioned Landcare Research

economist Florian Eppink to estimate the cost of changing an estimated 2% p.a. decline in

unmanaged kiwi nationwide into a 2% increase, so K4K could plan effective funding

strategies for achieving this goal. The original target deadline of early 2015 was changed to

late 2014 in order to support a Department of Conservation (hereafter DOC) and K4K bid to

Treasury for funding in the 2015 government budget. The bid was successful, although it did

not rely heavily on the Landcare Research analysis. The opportunity has since been taken to

strengthen technical data about kiwi populations and likely responses to management in a

revised report. These revisions include new kiwi population management scenarios and

underlying population modelling parameters developed by ecologists John Innes (Landcare

Research) and Hugh Robertson (DOC). Florian Eppink then estimated the cost of the new

scenarios to meet K4K’s original request. Unless otherwise credited, expert kiwi knowledge

in this report has come from Hugh Robertson, who has in turn derived information from

unpublished studies, knowledge, and sometimes opinions from many contributors to kiwi

recovery and its science.

3 Objectives

To determine additional management so that all 10 kiwi taxa will a) stop declining, or

b) increase by 2% per annum.

To estimate the costs of this additional management.

4 Modelling kiwi recovery strategies

4.1 Overview

Spanning two disciplines (in this case, ecology and economics) is never easy and this report

is no exception. We have tried to make both parts of the work understandable for all readers,

but the project is intrinsically complex. There are 10 kiwi taxa, whose populations are

subject in varying proportions to seven management regimes. We first modelled total

population growth rates using most likely numbers as well as other estimates above and

below them (e.g. low growth rate and high growth rate parameter choices). When we did

this, we discovered that some taxa were already meeting the population targets (either ‘no

decline’ i.e. 0% growth, or 2% growth), and so we did little further work with them. For just

the taxa that are not meeting our targets, we then modelled applying management to more and

more individuals in each population until annual growth rates reached the 0% or 2% targets.

Lots of different combinations of management regimes (that make up a conservation

scenario) could be applied, but we present just one or two conservation scenarios per taxon

(singular of ‘taxa’). We explain all of these terms in Appendix 1.

For each taxon of kiwi, we first estimated the 2015 population size, then allocated all

individuals to one of seven management regimes, each with its own estimated annual

population change rate. We then calculated the resultant nett change rate after 1 year and 15

years for each total population, considering all regimes applied.



The management regimes were: ‘Operation Nest Egg’ (ONE); ‘kohanga’ or island marooning

or ‘kiwi farming’; sustained predator trapping preferably with poisoning every 5–7 years;

aerial poisoning of predators every 3 years; captive breeding (eastern browns only); 1080 in

bait bags to control predators (Rakiura tokoeka only); and ‘do nothing’.

4.2 Kiwi taxa and estimated 2015 population sizes

There are uncertainties about both kiwi taxonomy and kiwi population sizes (Table 1), whose

future resolution will assist recovery planning.

Molecular studies have revealed that both North and South Island brown kiwi have regionally

subdivided population structures that Baker et al. (1995) referred to as ‘cryptic species’.

Burbidge et al. (2003) and Baker & Burbidge (unpub. data) analysed mitochondrial DNA and

suggested that there were four genetically and regionally distinct kinds of North Island brown

kiwi, in Northland, Coromandel and eastern (mainly Hawkes Bay, Bay of Plenty, East Cape)

and western (mainly Taranaki/Wanganui) North Island. These currently are aggregated as

Apteryx mantelli and share a threat status, and until their taxonomy resolves further will by

precautionary principle be managed separately (Herbert & Daugherty 2002; Holzapfel et al.

2008). Scientifically, the currently accepted 10 kinds of kiwi could be referred to as ‘known

or suspected recognisable taxonomic units’ but this is cumbersome. In this report, to avoid

confusion, we refer to the currently accepted 10 kinds of kiwi as ‘taxa’, even though

several do not have formal taxonomic description. We frequently refer to them by their

common name, e.g. ‘Coromandel and rowi’, but generally drop the words ‘kiwi’ and

‘tokoeka’ from these references simply to avoid repetition.

We estimated 2015 population sizes by taking published best guesses in Holzapfel (2008) and

calculating what these populations would have become 7 years later, by allocating the 2008

birds to either managed or unmanaged regimes. These regimes were assumed to result in

different growth rates – a 1–15% increase if managed and a 2–3% decline if unmanaged. To

acknowledge uncertainty in these 2015 population estimates, we also suggest maximum and

minimum error sizes in them: 10% for little spotted and rowi; 20% for Coromandel and

Haast; and 30% for all others. The increasing error margins reflect how well each population

is known, due to varying efforts of previous research and census, varying remoteness in New

Zealand, and the very different total areas (hectares) of each kiwi.

Area (ha) occupied by each taxon was determined by GIS calculations undertaken by DOC

staff. These calculations exclude areas where the population is extremely sparse and non-

viable.

We did not consider the management of populations that are, or could be, artificial hybrids

between different kiwi taxa (i.e. Ponui Island, Pukaha Mt Bruce, Rimutaka, and possibly

Hauturu/Little Barrier Island). Their management will contribute to species-level goals, but

not the taxon-specific goals considered in this report.

Table 1 Common and scientific names (OSNZ 2010), current NZ threat status, main criterion and explanatory qualifiers (Robertson et al. 2013), 2015 population size (most

likely, minimum, maximum), and estimated area occupied (H. Robertson pers. comm.) of all 10 kiwi taxa recognised in the Kiwi Recovery Plan 2008 – 2018 (Holzapfel et al.

2008). The mean density data in column 7 are derived by dividing the most likely 2015 population size (column 6) by the area occupied (column 7). Status qualifiers are: CD

conservation dependent, DE designated, DP data poor, Inc increasing, OL one location, PD partial decline, RF recruitment failure, RR range restricted

Common name Region Scientific name Current threat status Status criterion and qualifiers Population size 2015

Area (ha) occupied (mean density) 2015

Little spotted kiwi Apteryx owenii Recovering 1–5000 mature individuals.

CD, Inc, RR 1800

(1620–1980)

5600

(0.321/ha)

Great spotted kiwi A. haastii Threatened (nationally

vulnerable) 5–20 000 mature individ. 30–70% decline DP, RF

14 800

(10 360–19 240)

800 000

(0.019/ha)

North Island brown kiwi

Northland A. mantelli

Threatened (nationally vulnerable)

5–20 000 mature individ. 30–70% decline CD, PD, RF

8,200

(5740–10 660)

700 000

(0.012/ha)

Coromandel A. mantelli 1700

(1360–2040)

125 000

(0.014/ha)

Eastern A. mantelli 7150

(5005–9295)

1 400 000

(0.005/ha)

Western A. mantelli 7500

(5250–9750)

860 000

(0.009/ha)

Rowi (Okarito brown kiwi)

A. rowi Threatened (nationally critical)

<250 mature individuals CD, inc., OL, RF

500

(450–550)

15 000

(0.033/ha)

Tokoeka (southern brown kiwi)

Haast Apteryx australis australis

Threatened (nationally critical)

<250 mature individuals CD, inc., OL, RF

400

(360–440)

30 000

(0.013/ha)

Rakiura (Stewart Is.) Apteryx australis lawryi

Threatened (nationally endangered)

Moderate population, ongoing decline DE, DP, OL, RF

13 000

(9100–16 900)

151 100

(0.086/ha)

Fiordland Apteryx australis australis

Threatened (nationally vulnerable)

5–20 000 mature individ. 30–70% decline PD, RF

12 500

(8750–16 250)

800 000

(0.016/ha)



Kiwi distribution is approximated in Figure 1.

Figure 1. Spatial distribution of kiwi in New Zealand. North Island brown kiwi are managed as Northland,

Coromandel, eastern and western populations, while South Island tokoeka have three regional populations in

Haast, Fiordland and Rakiura (Stewart Island). Source: Kiwis for kiwi

4.3 Current kiwi threats and management regimes, and resultant estimated population growth rates

4.3.1 Threats and management regimes

Predation by pest mammals, particularly stoats (Mustela erminea) but also ferrets (Mustela

furo), dogs (Canis familiaris), and cats (Felis catus), is considered the key cause of current

kiwi declines (McLennan et al. 1996; Robertson et al. 2011). Other threats include loss of

genetic diversity and other localised events such as vehicle strikes, fire, disease, and ongoing

habitat loss (Holzapfel et al. 2008) but overcoming predation is undoubtedly the most

effective way to ameliorate these less important issues.

There are currently four major and two minor active management regimes for kiwi

(Holzapfel et al. 2008; Robertson & de Monchy 2012), and a seventh inactive one to which

most (76%, Table 2) kiwi are subjected – no pest management. The four major active regimes

combat mammalian predation in some way. They are:

Operation Nest Egg (ONE; Colbourne et al. 2005; Robertson et al. 2006; Gillies et al.

2013), in which eggs and young chicks are removed from predation and other risks in



the wild, then returned as subadults that have smaller likelihood of predation. Currently

we estimate that ca 540 kiwi of seven taxa are subject to ONE (Table 2).

Kohanga, marooning, or ‘kiwi farms’ in which populations are established on pest-free

islands or fenced sanctuaries, and birds are later harvested for translocation to

strengthen kiwi populations elsewhere. Little spotted kiwi are managed entirely in this

way (Ramstad et al. 2013). Currently we estimate that ca 2750 kiwi of nine taxa are

subject to kohanga (Table 2).

Trapping, preferably with episodic use of toxin every 5–7 years. Traps (DOC 200s,

DOC 250s, and others) are used to target stoats, ferrets, and cats on large scales,

particularly in DOC Kiwi Sanctuaries where trapping blocks average around 12 000 ha

(Robertson & de Monchy 2012). The occasional use of toxins that have a secondary

poisoning effect can eliminate resident, untrappable stoats. Currently, we estimate that

ca 8580 kiwi of eight taxa are protected by trapping (Table 2).

Aerial 1080 poisoning every 3–7 years. The broad-spectrum poison 1080 is aerially

applied to very large areas of New Zealand forest each year to target possums

(Trichosurus vulpecula) and ship rats (Rattus rattus) for conservation and disease

prevention objectives (Parliamentary Commissioner for the Environment 2011) but

with known secondary poisoning for stoats, ferrets, and cats. The frequency of

operations varies, also depending on objectives (Brown & Urlich 2005). Currently we

estimate that ca 3780 kiwi of eight taxa are protected by regular aerial 1080 operations

(Table 2). The recent landscape-scale use of aerial 1080 in the ‘Battle for our Birds’, in

response to an exceptionally widespread seeding of beech (Fuscospora and Lophozonia

spp.) trees and predicted resultant high numbers of rodents and stoats, will have

benefitted some kiwi populations for the first time. One-off aerial distribution of

brodifacoum is also used, to achieve eradications of mammal pests on islands and

fenced mainland sanctuaries only.

The offspring of 100 adult eastern browns held in captivity are also factored in for that taxon

only, and on Stewart Island, pest control has used ground-based poisoning methods rather

than aerial operations (Table 2).

In areas close to human communities or in remote areas where pigs are hunted, dogs are

significant threats to adult kiwi, especially in Northland (Robertson et al. 2011). Kiwi-

aversion training for dogs is a possible instrument to reduce kiwi mortality, but training needs

to be repeated at least every year (Dale et al. 2013) and its effectiveness has been questioned

(Jones 2006; R. Colbourne, Department of Conservation, pers. comm.). We accept that

aversion training may have value for kiwi recovery, but it has not been included as a

management regime in this analysis because of uncertainty about its effectiveness, and the

absence of data about population growth rates with and without it.

4.3.2 Current population growth rates

To enable us to model the outcomes of taking different management options, we allocated all

kiwi in each of the 2015 populations to a current management regime, for each of which we

estimated a particular resultant growth rate (finite rates of increase that may be >1 for

increasing populations or <1 for declining populations; Table 2). In this report we also

present growth rates as say ‘2% per annum’ because of its popular use. For example, a

2% increase, is simply a growth rate of 1.02, and a 2% decline is a growth rate of 0.98.



We have used published data on population growth rates under different regimes where

available (Holzapfel et al. 2008; Robertson et al. 2011; Robertson & de Monchy 2012), but

most rates data in Table 2 derive from unpublished data or expert assessment by Hugh

Robertson about how published rates for one taxon may apply to another, and how rates may

have changed over time. Most of the rates we select here have not been directly measured in

the wild for each taxon. Addressing this shortfall is clearly desirable in the future.

Mean per annum rates that we used in modelling (Table 2) were derived as follows:

a) Little spotted. Fortuitously, little spotted kiwi were moved to Kāpiti Island in 1912

because they became extinct on the mainland during the 20th

century. From Kāpiti,

‘insurance’ populations have been established on a further seven predator-free islands

(Anchor Island, Chalky Island, Hen Island, Long Island, Motuihe Island, Tiritiri

Matangi, Red Mercury Island) and at two mainland sanctuaries (Cape Sanctuary and

Zealandia). Therefore, kohanga is the only regime that applies to this taxon.

Population growth rates measured on Long, Red Mercury, Hen and Tiritiri Matangi

Islands during 1992–97 averaged 7.25% p.a. (Colbourne & Robertson 1997) but we

selected a slightly lower rate (5% p.a., i.e. 1.05) because the growth rate will slow as

K (carrying capacity) is approached. The lower growth rate (1.02) given to Kapiti

(which is at K) matches the ca 25 individuals that are harvested from there annually to

start new sites.

b) Great spotted. We gave ONE a smaller growth rate (1.03) than for North Island

browns or rowi because it has proven less successful. The trapping rate (1.02) is

derived from mean growth rates of kiwi calls of +1.7% p.a. at three stations in the

south Hurunui (trapping with some ground toxins). The 1080 rate (1.003) is based on

call counts increasing at 8 listening stations under intermittent aerial 1080 at Gouland

Downs (5 stations) and Heaphy (3 stations). A ‘do nothing’ growth rate of 0.98 (i.e. a

decline) reflects an overall 1.97% p.a. decline in call rates at 10 unmanaged listening

stations in Westport coal measures (4), the Taramakau (3), and North Hurunui (3)

over 17–18 years since the mid-1990s, and a mean 1.6% p.a. decline in the number of

territories in 2000 ha of the northern Hurunui during 2000–2015 (Robertson et al.

unpub. data).

c) Northland. ONE in Northland resulted in a mean growth rate of 1.125 (Robertson et

al. 2011). The kohanga rate (1.10) derives from the number of birds that have been

removed from Motuora and Matakohe Islands over ca 12 years. The trapping rate

(1.06) is derived from Northland sanctuary data (8.6 % p.a. increase, Robertson & de

Monchy, 2012) but is slightly smaller to account for trap-shy stoats arising from

continuous trapping, as well as unsustainable trap-checking and baiting practices. The

1080 rate (1.02; Waipoua Forest only) is derived as per western (below). The ‘do

nothing’ rate (0.97) is from Robertson et al. (2011) and Holzapfel et al. (2008).

d) Coromandel. As with Northland, except while original growth from trapping was

observed to be 11.3% p.a. (Robertson & de Monchy 2012), chick survival declined in

the last few years when kiwi were monitored closely.

e) Eastern. ONE, trapping, aerial 1080 and ‘do nothing’ rates are all as per Northland,

although ferrets are more important than dogs as decline factors. The c.15 sites that

hold ca100 easterns in captivity release a surplus of ca 5 birds per year, hence an



additive 1.05 growth rate from that regime. The 100 adults allocated to a kohanga are

all at Cape Sanctuary (Cape Kidnappers) and reflect likely numbers in the very near

future.

f) Western. The ONE programme at Tongariro had high hatching success and chick and

subadult survival, resulting in a high growth rate (1.15) from these birds (Robertson &

de Monchy 2012). The 1080 rate (1.02) is based on a 14-year mostly unpublished

study at Tongariro Forest that has monitored brown kiwi productivity through 5-

yearly aerial 1080 operations (Robertson & de Monchy 2012; J. Guillotel, H.

Robertson, N. Sutton, DOC, unpub. data). Other rates are derived as per Northland.

g) Rowi. Rowi rates are derived as per western, except that aerial 1080 is given a smaller

rate (1.01) because unpublished data suggest the rowi response to these operations is

not as good. That may be because rowi chicks go to and from nests repeatedly and so

may be found more readily by stoats. We used 1.15 for ONE for rowi rather than

1.094 as in Robertson and de Monchy (2012), because ONE management for this

species has improved greatly since the early 2000s.

h) Haast. Mean annual growth under ONE was measured at 7.1% p.a. by Robertson and

de Monchy (2012) but Hugh Robertson considers that 5% p.a. growth (rate 1.05) is

likely to be more accurate now. The kohanga rate of 1.10 is based on other kiwi taxa

in predator-free sites; of kohanga sites with Haast tokoeka, Coal Island (1189 ha) has

abundant room for population growth, while Raratoka (86 ha) and Orokonui Eco-

sanctuary (307 ha) are much smaller and will reach K sooner. The rate under stoat

trapping is known to be low (1.03) because intermittent beech (Fuscospora and

Lophozonia spp.) masts resulted in numerous stoats that killed many radio-tagged

chicks, despite trapping (Robertson & de Monchy 2012). The predicted growth rate if

nothing is done is 0.97, a decline (Holzapfel et al. 2008).

i) Fiordland. Growth rates are predicted to be low (1.05) for Fiordland kohanga kiwi

because these very southern sites (Secretary and Resolution Islands, 45–46° S) may

have intrinsically low productivity, Secretary is intermittently colonised by stoats,

Resolution has mice (Mus musculus) that may compete with kiwi for invertebrate

prey, and access to both islands to harvest kiwi is comparatively difficult. Rates for

trapping and ‘do nothing’ regimes were measured in the field and are from Tansell,

Edmonds and Robertson, Department of Conservation, unpub. data. The population

change rate under aerial 1080 (1.02) is from the long-term, measured result for

westerns at Tongariro Forest (see above).

j) Rakiura. Our suggested growth rate for Rakiura tokoeka in kohanga (1.10) is higher

than for Fiordland tokoeka because the sites (Ulva Island and Dancing Star sanctuary)

are small (270 ha and 160 ha respectively) and readily accessed to harvest birds.

There are no mustelids on Rakiura and so only feral cats are targeted by trapping. The

suggested growth rates of 1.04 under this regime, and for ground-based poisoning, are

simply best guesses. The 0.98 growth rate (2% per annum decline) is from Holzapfel

et al. (2008), and from mapping territories at Masons Bay using trained dogs and

radio transmitters on birds in a 125 ha area during 1993–2013 (R. Colbourne, H.

Robertson, DOC, unpub. data).

Table 2 ‘Best estimate’ (and min.-max.) current numbers of all 10 kiwi taxa that are subject to different management regimes, and the mean per annum population growth

rates that apply to each (see 4.2.2 for derivations). Rounded, best estimate, min. and max. population sizes after one and 15 years derived from ‘best estimate’ current rates

are also shown, as are mean, whole-population, per annum growth rates after 1 and 15 years

Regime No. kiwi in each regime Current p.a. growth rate per regime

Population size after… Mean, nett, p.a. growth rate after… 1 year 15 yrs 1 year 15 years

Little spotted

Kohanga (all but Kapiti) 600 1.05 1.030 1.032

Kohanga (Kapiti) 1200 1.02 TOTAL 1800 1852 2867

MIN-MAX 1620–1980 1669–2039 2527–3088

Great spotted

ONE 8 1.03

0.983 0.984 Trapping w. 5–7 yr toxin 350 1.02 1080 each 5–7 years 1500 1.003 Do nothing 12942 0.98

TOTAL 14800 14 592 12 428 MIN-MAX 10 360–19 240 10 202–18 904 9762–14 889

Northland

ONE 40 1.125

1.015 1.028 Kohanga 60 1.1 Trapping w. 5–7 yr toxin 3900 1.06 1080 each 3 years 75 1.02 Do nothing 4125 0.97

TOTAL 8200 8323 12 325 MIN-MAX 5740–10 660 5828–10 818 8654–15 995

Coromandel

ONE 50 1.125

1.040 1.048 Kohanga 40 1.1 Trapping w. 5–7 yr toxin 1180 1.06 Do nothing 430 0.97

TOTAL 1700 1768 3411 MIN-MAX 1080–1620 1417–2119 2780–4043

Eastern

ONE 100 1.125

0.99 1.001

Captive release 100 1.05 Kohanga 100 1.05 Trapping w. 5-7 yr toxin 1150 1.06 1080 each 3 years 50 1.02 Do nothing 5650 0.97

TOTAL 7150 7078 7281 MIN-MAX 5005–9295 4957–9199 5131–9432

Regime No. kiwi in each regime Current p.a. growth rate per regime

Population size after… Mean, nett, p.a. growth rate after… 1 year 15 yrs 1 year 15 years

Western

ONE 100 1.15

1.002 1.013 Kohanga 130 1.1 Trapping w. 5–7 yr toxin 1350 1.06 1080 each 3 years 1700 1.02 Do nothing 4220 0.97

TOTAL 7500 7516 9064 MIN-MAX 5250–9750 5267–9766 6423–11 704

Rowi

ONE 120 1.15 1.047 1.039 Kohanga 20 1.1

1080 each 3 years 360 1.01 TOTAL 500 524 891

MIN-MAX 450–550 473–574 833–950

Haast

ONE 120 1.05

1.037 1.042 Kohanga 60 1.1 Trapping w. 5–7 yr toxin 140 1.03 Do nothing 80 0.98

TOTAL 400 415 738 MIN-MAX 360–440 374–455 676–799

Fiordland

Kohanga 500 1.05

0.988 0.99 Trapping w. 5–7 yr toxin 500 1.012 1080 each 3 years 100 1.02 Do nothing 11400 0.984

TOTAL 12500 12 351 10 722 MIN-MAX 8750–16 250 8645–16 056 7506–13 939

Rakiura

Kohanga 40 1.1

0.981 0.982 Trapping w. 5–7 yr toxin 10 1.04 Toxin in bait stations 200 1.04 Do nothing 12 750 0.98

TOTAL 13 000 12 757 9962 MIN-MAX 9100–16 900 8930–16 579 6977–12 842



In total, 24% of the estimated 68 000 remaining kiwi (all 10 taxa) are under some

management, and the remaining majority (76%) are unmanaged. However, the proportion of

each taxon’s population that is under management varies greatly, from 2% for Rakiura

tokoeka to 100% for little spotted kiwi.

Across all kiwi taxa, there is an inverse relationship between total population size and the

proportion of each population that is pest-managed (Fig. 2).

Figure 2. Relationship between total population size and % of each population that is pest-managed, for all 10

kiwi taxa.

4.3.3 Modelling 15-year outcomes at current sites

We modelled population size and mean annual growth rates of all 10 kiwi taxa within 1-year

and 15-year horizons by assuming that:

a) the same places and areas (hectares) are managed for the whole 15 years

b) new birds produced under each regime recruit within the managed area and do not

disperse outside it

c) there are no K effects on population size within the 15-year period

d) management effectiveness (pest control efficacy, and kiwi demographic responses to

it) remain the same from year to year.



We selected 15 years because it is sufficient time for differences between combinations of

regimes to become apparent, yet is short enough to drive planning decisions now.

Whole population growth rates can change a little in 15 years because the numbers of kiwi

within the managed areas grow cumulatively, while those within unmanaged areas slowly

decline, so that different numbers and proportions of kiwi are subject to each regime as time

passes. Kiwi will eventually disappear entirely from unmanaged places and remain only in

pest-managed ones if such scenarios persist, as is the case already for other more pest-

sensitive birds such as kokako (Callaeas wilsoni) and saddleback (Philesturnus

carunculatus).

Under current management (status quo) for 15 years using most likely population growth

rates, five taxa (little spotted, Northland brown, Coromandel brown, rowi and Haast tokoeka)

are estimated to increase at mean annual rates that already exceed 2% per annum. Eastern

and western browns will increase but at <2% per annum. The remaining three taxa are

estimated to decline at varying mean annual rates: 1.0% p.a. for Fiordland tokoeka, 1.6% p.a.

for great spotted and 1.8% p.a. for Rakiura tokoeka (Tables 2, 3).

Selecting low or high growth rate parameters changes these outcomes and classifications in

negative and positive directions respectively (Table 3). Compared with best estimate growth

rates, in 15 years with low (best estimate minus 30%) rates of growth, Northland slips from

increasing at >2% p.a. to increasing at <2% p.a., while easterns change from increasing to

declining. With high (best estimate plus 30%) rates, western browns are boosted from

increasing at less than 2% p.a. to increasing at more than 2% p.a. (Table 3).



Table 3 Effects of varying population growth rates (best estimate, ±30%) under the various management

regimes (section 4.2.2) on current and modelled future (rounded 1 year, 15 years) population size and mean, per

annum, total-population growth rate for all 10 kiwi taxa.

Taxon Best estimate growth rates Low growth rates (–30%)

High growth rates (+30%)

Current 1 year 15 yrs 1 year 15 yrs 1 year 15 yrs

Little spotted Population 1800 1854 2867 1838 2457 1870 3211

Total rate 1.030 1.032 1.021 1.021 1.039 1.039

Great spotted Population 14800 14 553 11 610 14 472 10 707 14 635 12 599

Total rate 0.983 0.984 0.978 0.979 0.989 0.989

Northland Population 8200 8323 12 325 8212 9808 8434 15 457

Total rate 1.015 1.028 1.001 1.012 1.029 1.043

Coromandel Population 1700 1768 3411 1740 2650 1796 4375

Total rate 1.04 1.048 1.024 1.03 1.057 1.065

Eastern Population 7150 7078 7281 6998 5694 7158 8898

Total rate 0.990 1.001 0.979 0.988 1.001 1.015

Western Population 7500 7516 9064 7436 7536 7597 10 938

Total rate 1.002 1.013 0.991 1.000 1.013 1.025

Rowi Population 500 524 891 517 764 531 1033

Total rate 1.047 1.039 1.033 1.029 1.061 1.050

Haast Population 400 415 738 409 594 420 926

Total rate 1.037 1.042 1.023 1.027 1.050 1.058

Fiordland Population 12 500 12 351 10 722 12 286 9845 12 415 11 691

Total rate 0.988 0.990 0.983 0.984 0.993 0.996

Rakiura Population 13 000 12 757 9962 12 677 9016 12 838 11 019

Total rate 0.981 0.982 0.975 0.976 0.988 0.989

We estimate that if current management is maintained at all sites for 15 years, then there

would be for all 10 kiwi taxa combined a decline of 0.1% per annum. That is, current

management is close to holding the national kiwi population stable. However, declines in a

few, currently more abundant taxa (Rakiura, Fiordland, great spotted) roughly equate to

increases in more but smaller population taxa (Coromandel, Haast, rowi, little spotted,

Northland, western).

We also estimate that if all management ceased, but assuming that island biosecurity

continued so that there were no pest invasions to islands, there would be a national all-kiwi-

taxa decline of 2.0 % per annum, as already widely publicised.



4.4 Modelling halting the decline and achieving 2% per annum growth

For each taxon failing to achieve 0% p.a. or 2% p.a. growth under current management, we

then modelled increasing the number of kiwi subject to active management using our

opinions about the most practicable and acceptable management regimes in each case, until

the whole population change rate achieved the mean 0% p.a. or 2% p.a. target over 15 years.

Other combinations of numbers of birds subject to different management are possible, and

may reach the desired targets, but at different costs to those estimated here.

We repeated this modelling for each taxon with estimated maximum and minimum values for

the initial (2015) population size and estimated low and high (± 30%) population growth rates

under the different regimes, some results of which we report here.

4.4.1 Halting the decline

‘Halting the decline’ means achieving at least 0% population growth per annum over the

modelled 15-year period; that is, the population in 2030 will be the same as it is in 2015.

With most likely growth rate parameters from the various management regimes (section

4.2.2), populations of all taxa except great spotted, Fiordland, and Rakiura, will have grown

in 15 years at the current rate of investment in their recovery. With low growth rate

parameters used in the modelling, eastern browns also fail to achieve growth (Table 3).

In our suggested scenarios, subjecting extra kiwi to aerial 1080, trapping or kohanga regimes

halts the decline of great spotted, eastern brown, and Fiordland populations, while on Rakiura

this is achieved by increasing use of ground-poisoning (Table 4).

Table 4 Possible conservation scenarios of allocating kiwi to different management regimes that achieve 0% p.a. growth (i.e. halt the decline). Only taxa and situations that

required re-allocation of birds between management regimes to achieve 0% p.a. growth are shown. Figures in bold and italics show the total numbers needed under that

management regime (removed from the do-nothing category) to halt the decline. Figures in brackets for eastern browns under the low growth rate parameters show an

example, alternative, allocation scenario using trapping rather than aerial 1080 that also halts decline

‘Kind' of kiwi Regime No. kiwi allocated to each regime Current best estimate population

Revised best estimate population

Minimum pop. (–30%)

Maximum pop. (+30%)

Low growth rates (–30%)


Great spotted

ONE 8 8 8 8 8 8 Trapping w. 5–7 yr toxin 350 350 350 350 350 350 1080 each 5–7 years 1500 11 878 8101 15 654 12 921 10 278 Do nothing 12 942 2564 1901 3228 1521 4164

2015 TOTAL 14 800 14 800 10 360 19 240 14 800 14 800 MEAN 15-YR RATE 0.984 1.0 1.0 1.0 1.0 1.0

Eastern

ONE 100 100 (100) Captive release 100 100 (100) Kohanga 100 100 (100) Trapping w. 5–7 yr toxin 1150 1150 (2060) 1080 each 3 years 50 1792 (50) Do nothing 5650 3908 (4740)

TOTAL 7150 7150 MEAN 15-YR RATE 1.001 1.0

Fiordland

Kohanga 500 500 350 650 500 500 Trapping w. 5–7 yr toxin 500 500 350 650 500 500 1080 each 3 years 100 3271 2290 4252 5385 1394 Do nothing 11 400 8229 5760 10 698 6115 10 106

2015 TOTAL 12 500 12 500 8750 16 250 12 500 12 500 MEAN 15-YR RATE 0.990 1.0 1.0 1.0 1.0 1.0

Rakiura

Kohanga 40 40 40 40 40 40 Trapping w. 5–7 yr toxin 10 10 10 10 10 10 Toxin in bait stations 200 3060 2100 4020 4945 1690 Do nothing 12 750 9890 6950 12 830 8005 11 260

TOTAL 13 000 13 000 9100 16 900 13 000 13 000 MEAN 15-YR RATE 0.982 1.0 1.0 1.0 1.0 1.0



4.4.2 Achieving 2% growth p.a.

Five of the 10 kinds of kiwi (little spotted, Northland, Coromandel, rowi, and Haast) are

already estimated to be increasing at 2% per annum with most likely growth rate parameters

under the various management regimes (section 4.2.2). With low growth rate parameters,

Northland brown kiwi slip below 2% p.a. increase. With high growth rate parameters, only

the most struggling populations – great spotted, eastern, Fiordland and Rakiura – still fail to

achieve 2% growth p.a. (Table 3).

Achieving mean annual growth of 2% p.a. over 15 years is substantially more demanding

than just halting the decline. In our suggested scenarios, substantially more trapping and/or

aerial 1080 can eventually achieve 2% growth p.a.for great spotted, Northland, eastern and

western kiwi, although with low growth input rates, 96% of each of the great spotted and

eastern populations have to be managed to do so (Table 5). With low growth rate parameters,

on Rakiura 80% (10 350/13000) of all tokoeka may have to be under protection by trapping

and ground-poisoning to maintain this as a mean annual growth over 15 years.

For Northland and Coromandel populations we manipulated the number of kiwi subject to

trapping rather than aerial 1080 because of the availability of community labour and likely

opposition to aerial 1080.

For eastern brown kiwi, having 100 birds under a kohanga regime at Cape (Kidnappers)

Sanctuary is reasonable, but if this site could be built up rapidly to 300 kiwi by translocation

from unmanaged populations, then our scenarios could change. Adding 200 birds to kohanga

at Cape Sanctuary could relieve 1000 others from requiring aerial 1080 to achieve the same

outcome.

Our preliminary modelling suggests that for great spotted kiwi, increasing the frequency of

aerial 1080 from every 5–7 years to every 3 years, with a resultant growth rate change from

1.003 to 1.02, can achieve 2% p.a. gain with all parameter choices except that with low

growth rates. In that case, maximising the number of birds under trapping and aerial 1080

would achieves 15-year mean per annum rate of only 1.4% (Table 5).

Similarly, substantial increases in the amount of aerial 1080 poisoning used in Fiordland can

achieve a population increase of 2% per annum over 15 years with all parameter choices but

one. With low growth rate parameters, this may be unobtainable (Table 5), because ONE is

not likely to be an efficient option in such a large population in the remote and difficult

Fiordland landscape, where, unlike Haast, the population is widely scattered across the range,

kohanga space on islands is limited, and mean annual growth from aerial 1080 may be

unpredictable because of intermittent beech masts and high stoat numbers, or there could be a

lack of rodents to carry the toxin to stoats in intervening years. No monitoring of Fiordland

tokoeka populations through a 1080 operation has ever been carried out.

Table 5 Possible conservation scenarios of allocating kiwi to different management regimes that achieve 2% p.a. growth. Only taxa and situations that required re-allocation

of birds between management regimes to achieve 2% growth p.a. are shown. Figures in bold and italics show the total numbers needed under that management regime

(removed from the do-nothing category) to achieve 2% p.a. growth. The highlighted cells for great spotted and Fiordland under low growth rates are the only cases where

manipulating regimes did not result in a 2% p.a. population gain. Figures in brackets for eastern and western browns under the low growth rate parameters show example,

alternative, allocation scenarios using trapping and kohanga rather than aerial 1080 that also cause 2% growth p.a.

Kiwi taxon Regime No. kiwi allocated to each regime Current best estimate population



Maximum pop. (+30%)



Great spotted

ONE 8 8 8 8 8 8

Trapping w. 5–7 yr toxin 350 700 700 700 3200 700

1080 each 3 years (a change) 1500 14 091 9651 18 531 11 592 11 306

Do nothing 12942 1 1 1 0 2786

2015 TOTAL 14 800 14 800 10 360 19 240 14 800 14 800

MEAN 15-YR RATE 0.988 1.02 1.02 1.02 1.014 1.02

Northland

ONE 40 40

Kohanga 60 60

Trapping w. 5–7 yr toxin 3900 4843

1080 each 3 years 75 75

Do nothing 4125 3182

2015 TOTAL 8200 8200

MEAN 15-YR RATE 1.028 1.02

Eastern

ONE 100 100 70 130 100 (100) 100

Captive release 100 100 100 100 100 (100) 100

Kohanga 100 100 70 130 100 (300) 100

Trapping w. 5–7 yr toxin 1150 1150 805 1495 1150 (3603) 1150

1080 each 3 years 50 3336 2289 5749 5388 (50) 1058

Do nothing 5650 2364 1660 3005 312 (2997) 4642

2015 TOTAL 7150 7150 5005 10660 7150 7150

MEAN 15-YR RATE 1.001 1.02 1.02 1.02 1.02 1.02

Kiwi taxon Regime No. kiwi allocated to each regime Current best estimate population



Maximum pop. (+30%)



Western

ONE 100 100 100 100 100 (100)

Kohanga 130 130 91 169 130 (300)

Trapping w. 5–7 yr toxin 1350 1350 945 1755 1350 (3025)

1080 each 3 years 1700 3146 2092 4200 5455 (1700)

Do nothing 4220 2774 2022 3526 465 (2375)

2015 TOTAL 7500 7500 5250 9750 7500

MEAN 15-YR RATE 1.013 1.02 1.02 1.02 1.02

Rakiura

Kohanga 40 40 40 40 40 60


Ground-based poisoning 200 7292 5063 7032 7310 4990

Do nothing 12750 5658 3987 7328 2650 7940

2015 TOTAL 13 000 13 000 9100 16 900 13 000 13 000

MEAN 15-YR RATE 0.982 1.02 1.02 1.02 1.02 1.02

Fiordland

Kohanga 500 500 350 650 700 500


1080 each 3 years 100 10 980 7686 14 274 11 300 8310

Do nothing 11400 520 364 676 0 3190

2015 TOTAL 12 500 12 500 8750 16 250 12 500 12 500

MEAN 15-YR RATE 0.990 1.02 1.02 1.02 1.015 1.02



5 Estimating current and additional cost

Kiwi conservation involves predator control as well as a range of other supporting activities,

such as advocacy, and kiwi call monitoring. Our first analysis of the data K4K requested

from the kiwi conservation groups considered the proportion of community costs that are

volunteered or funded.

Our second analysis focuses on the costs of stabilising and increasing the populations of the

kiwi taxa that are not already achieving these targets (eastern, western, great spotted,

Fiordland, Rakiura), through additional management effort, for all of the population model

parameter options (most likely, high/low initial population, high/low growth rates). We

estimated these costs using data from the reporting provided by the kiwi conservation groups,

from published sources and DOC’s internal reporting systems.

We estimated the present value of the additional costs over 15 years with a 10% discount rate

in accordance with Treasury guidance.1 Discounting is an economic technique that accounts

for people tending to prefer having money now, rather than having a little more money later.

Discounting is an essential consideration when making decisions about long-term

investments, and the discount rate is a critical parameter. A low (cf. high) discount rate means

people weigh future costs more (cf. less) heavily in their decisions; thus the present value of

future costs will be higher (cf. lower). Therefore we also offer cost estimates at 5% and 15%

discount rates to illustrate the impact of time preferences that deviate from the Treasury

guidance.

5.1 Cost data considerations

The data provided by kiwi conservation groups at the request of K4K are critical for this

exercise.

The communities reported on a range of cost items, which we relate to costs based on

publicly available information as described in Appendix 2. This approach provides an

estimate for the costs communities incur under the current conservation scenario, and can be

used to estimate the additional costs of other conservation scenarios.

Due to decisions we made about whether to include or exclude certain costs (mainly fences)

and cyclic implementation of management regimes (mainly the 6-year cycle for predator

control using poisons), there will inevitably be discrepancies between our cost estimates

based on community reporting and our suggested management regimes and conservation

scenarios. Our cost estimates should be considered as preliminary.

Data sources of note are Gillies et al. (2013) for cost estimates per ONE juvenile released

(although the quality of their data also relied heavily on interpretation of queries made to

1 http://www.treasury.govt.nz/publications/guidance/planning/costbenefitanalysis/primer/15.htm (Accessed

February 23rd, 2015)

http://www.treasury.govt.nz/publications/guidance/planning/costbenefitanalysis/primer/15.htm



users), PCE (2013), and DOC’s experience of the costs per hectare of aerial poisoning

operations. For several cost items, particularly trapping equipment, we found vendor prices

and applied sensitivity analysis to them. This provided an error range that proved to be

insignificant compared with the total costs; therefore the average of the error range was used

for the cost estimates.

The level of reporting about different kiwi taxa inevitably reflected the number of community

conservation groups actively managing each of them. For Northland brown, for instance, we

have many reports. This suggests that the averages of cost items are a good reflection of the

actual costs for Northland brown. The number of community groups reporting on the other

kiwi was (much) smaller, and the costs of management regimes show significant variation

across taxa. Deeper analysis of the reported data to understand the cause of this variation was

not possible; we have therefore taken the data at face value.

For the kiwi taxa and management regimes for which we have no community reports, we

applied average costs of items from reported K4K data to produce estimates of additional

annual costs of the management regimes and conservation scenarios. This was done for the

(very small) community management of Fiordland and Rakiura tokoeka, and for the use of

toxins for western brown. Thus, for these taxa and management regimes, the cost estimates of

additional management are based on national cost averages, not taxon-specific data.

The K4K data distinguish between funded and volunteered hours spent on various activities

and the equipment in use. In addition, we assume communities do not account for capital

wear and tear by preparing for capital replacement. The full economic cost of kiwi

conservation is therefore higher than the current level of funding, and we report on this

‘volunteer contribution' for the current situation.

For the ‘sustainable trapping with poison’ regime, we allocate appropriate reported cost items

from the K4K data to this regime and derive a per-hectare cost. In this approach we assume

time and equipment used in the scenarios increase linearly with kiwi distribution (hectares)

based on the number of birds in the first year (see 4.3.3) and that the ratio of funded and

volunteered effort remains stable with additional management.

Under the status quo, we assume communities apply continuous trapping with pulsed poison

operations. This is probably unlikely in many instances, but the K4K data do not allow us to

identify the poisoning practices that communities use.

The community-reported data cover a wide range of equipment and activities. Not all these

relate directly to the management regime ‘sustained trapping with poisoning’. Advocacy, for

instance, is important both in attracting volunteers and funding, and in making the wider

population more aware of how they might unwittingly affect kiwi populations. However,

there is no basis for saying that advocacy will increase with more trapping. Hence, we do not

include such indirect cost items in the estimate of the cost of achieving population growth or

stability.

Predator exclusion fences help to protect kiwi as well as other species inside the fenced area,

so ideally we would have allocated a share of the costs to kiwi, but there is no meaningful

basis to do so. Given that the maintenance and depreciation of these fences is likely to

continue regardless of kiwi, we decided to exclude fence costs from the analysis.



The kohanga regime is assumed to continue at the cost level of the status quo. Additional

costs arise from transferring birds to the kohanga sites, other than for Fiordland and Rakiura

tokoeka, which we assumed to be managed by DOC (see below), and have not been included

in the analysis. Here, for the sake of simplicity, we assume that each transferred bird has a

one-off cost of $1,000, and that the full number of additional birds is transferred in the first

year. In practice this is unlikely to be possible.

The increased number of kiwi under a given management regime provides the additional area

and cost for that regime under each conservation scenario via derived bird densities. These

bird densities are based on our expert opinion that 95% of kiwi populations inhabit 30% (for

‘the brown kiwi’) and 60% (great spotted kiwi, Fiordland and Rakiura tokoeka) of the

potential habitat. We assume that the management regimes target kiwi populations with

higher bird densities, which limits the extra area that is required under the additional

management to achieve stability and growth.

We additionally assume that the area under management does not increase after the first year,

i.e. additional birds do not disperse beyond the boundaries of new and old conservation sites.

This implies that the bird densities in such areas can increase without limit under the new

management to achieve stability and growth. This may not reflect ecological reality and

expanding managed areas may prove to be necessary. However, threshold bird densities to

trigger such expansion could not be modelled in this project. The assumption implies that the

cost estimates may well be underestimates of the actual additional conservation funds

required.

5.1.1 How this report handles DOC costs

DOC currently receives NZ$1.7 million annually to run the five Kiwi Sanctuaries. Of these

funds, around NZ$850,000 is allocated to the Ōkārito and Haast Kiwi Sanctuaries, where

ONE is a significant share of the expenditures. The Kiwi Sanctuaries for Northland

(Whangārei), Coromandel (Moehau) and western brown kiwi (Tongariro) share the

remaining portion of the budget. Funds are spent on staff, research, toxins, traps, and other

equipment, such as quad bikes and radio transmitters. No specific information was found

about expenditure for the management of little spotted kiwi.

With the exception of aerial 1080, it was beyond the scope of this report to obtain reliable

DOC costs per regime, or to obtain reliable DOC costs per taxon. Our assumption is that

DOC expenditures, e.g. for kiwi sanctuaries, research, and Community Conservation

Partnership Funding to kiwi projects, remain at their current levels. Therefore: 1) we derived

the annual cost of current management per taxon for community groups only; 2) we derived

costs of additional management using trapping and poisoning cost data not from DOC but

from community groups, unless otherwise stated; and 3) in the analysis of annual current

costs, we exclude taxa managed primarily by DOC (little spotted, rowi, Haast, Fiordland, and

Rakiura).

We note that the involvement of DOC staff in community conservation efforts is likely to

raise the (labour) cost of kiwi conservation significantly (see Appendix 1, ‘Time’), compared

with funded and volunteered actions by community conservation groups.



5.2 Annual cost of current management

For the current management scenario, we used the K4K reported data on, e.g. the time spent

on activities and the number of traps used to estimate the cost of the current kiwi

conservation effort. Thus, we have a baseline cost against which the other scenarios can be

evaluated. Table 6 provides a summary of community costs for the five kiwi taxa with

substantial community involvement, but excludes DOC expenditures as explained above.

The management cost of kohanga kiwi differs across taxa, with particularly high costs for

eastern and western brown. In both cases, a large amount of time was reported for checking

bait stations. For all kiwi taxa, the combined total annual cost of kohanga is just over

$616,000.

Kohanga sites for eastern and western brown have long stretches of pest-fencing that benefits

kiwi as well as other species. A share of annual fence maintenance and depreciation costs

could be allocated to kiwi conservation, but we have no way to determine the size of that

share. We can note, however, that our cost estimate for kohanga sites is low because our

estimates exclude pest-fence costs.

Table 6 Estimates of annual costs reported by communities for management of the five kiwi taxa with

substantial community involvement, derived by applying data collected by K4K to the status quo. Costs are split

between kohanga kiwi and other community-led conservation activities. For community activities, a further

distinction is made between costs for trapping and poisoning, and indirect costs such as advocacy and general

capital. The ‘T&P/I ratio’ indicates how many dollars are spent on trapping and poisoning per dollar spent on

indirect costs (higher ratio means more money is spent on predator control). ‘Total’ indicates the sum of funded

(e.g. contracted) and volunteered conservation actions, and unfunded capital depreciation. The ‘donated

resources’ expresses the share of volunteered and uncosted contributions to the total conservation effort

Kiwi taxa Kohanga total

($)

Community Trapping & poison total

($)

Indirect total

($)

T&P / I ratio All costs total

($)

Donated resources

(%)

Great spotted 0 175,448 456,952 0.38 632,400 24.9

Northland 54,408 1,696,309 1,507,447 1.13 3,203,756 37.9

Eastern 154,612 383,806 452,771 0.85 836,577 55.8

Western 386,840 437,547 416,171 1.05 853,718 44.7

Coromandel 20,552 352,252 399,153 0.88 751,405 59.3

All taxa 616,411 3,045,363 3,232,493 0.86 6,277,856 44.5

Since indirect costs may not be directly related to controlling predators per se, it is possible

that these costs are stable regardless of the level of trapping and poisoning. These costs could

be regarded as ‘overhead’ or fixed costs of enabling predator control. The ‘TP/I’ ratio shows

that, for all taxa combined, for every dollar spent on administration, advocacy, etc, $0.86 is

spent on predator control.

This suggests community groups spend more time procuring funding, raising awareness and

carrying out administrative tasks, than they do on predator control. Groups managing

Northland brown have low indirect costs, whereas groups managing great spotted kiwi report



higher indirect costs. Further data and research will be required to understand the cause of

these differences and to develop potential guidelines.

The total (trapping and indirect) annual cost of community-actioned kiwi conservation is $6.3

million. By far the highest financial effort is put into the conservation of Northland brown

kiwi; eastern, western, and Coromandel brown get less, and great spotted receives the

smallest community conservation effort of these taxa. For Fiordland and Rakiura tokoeka, we

have no community reports.

Of this $6.3 million, community groups contribute around 44% in voluntary contributions on

average. This proportion is 59% for groups managing Coromandel browns and 25% for

groups working with great spotted kiwi.

The bulk of the voluntary contribution is volunteer time. Although trap depreciation (‘saving

for replacement’) can run into thousands of dollars for some groups, it is a small cost

compared with the time volunteers spend on checking and setting traps. Consequently,

keeping up advocacy is necessary to recruit new volunteers. Additionally, community

funding is generally short term and re-application for funding may be needed at intervals (M.

Impey, K4K, pers. comm.). Community groups continuously need to develop and secure

funding to continue operations.

These deductions may partially explain our finding that community groups spend less on

predator control than on, say, administration. There may be a self-sustaining element of

overhead costs in kiwi conservation that could be reduced by providing community groups

with more long-term financial security. This would allow groups either to focus more on

predator control or to reduce costs. Developing options for new funding models could be one

area for further research.

5.3 Additional cost of population stability and growth targets

In this section, we estimate the additional cost of achieving 0% (i.e. stability) and 2% growth

p.a. under various model parameter choices and conservation scenarios compared to the

status quo.

Over 15 years, these costs represent a significant investment commitment, which can inform

decision-making on options for kiwi conservation or research investments. We provide the

(temporally weighted) present value of the annual costs of the 15-year period of the

population model, discounted at 10% (the temporal weighting factor). We also provide the

present value at a 5% and 15% discount rate to show how the discount rate affects the present

value.

The costs for the management regime ‘ONE’ were taken from Gillies et al. (2013). The costs

for kohanga are based on DOC experience. The costs for the ‘sustained trapping and

poisoning’ regime come from the K4K reported data (total annual trapping and toxin costs).

The costs for ‘aerial poisoning’ are based on expert assessment of the numbers reported in

PCE (2013).

As discussed above, for Fiordland and Rakiura tokoeka and western brown, some costs of the

management regimes are national averages rather than specific to these taxa. Coromandel



brown requires no extra effort under any of the parameter choices (Table 2) and is therefore

not shown here.

Note that the results are estimates of costs that are additional to the status quo (estimated

$6.3 million plus current DOC expenditures on kiwi conservation). This illustrates the extra

financial effort that is needed to achieve the conservation targets, and as noted above, most

costings (but not aerial 1080) use community group data. If the current funding and volunteer

contributions do not continue at current levels, the need for additional funding increases

accordingly.

5.3.1 Northland

Northland brown only requires additional conservation effort in the parameter choices of a

2% p.a. growth target and low growth rates. The estimate of additional annual cost compared

with the status quo is shown in Figure 3. Sustained trapping with pulses of poison baiting are

the only management regime, which has an additional annual cost of around $410,000.

Figure 3. Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for Northland

brown kiwi. In this and following graphs, $0 cost (no graph bars) means that the taxon population

already achieves 0% or 2% growth p.a. (Table 2).

The present value of the additional annual costs of this scenario in the 15-year period is just

over $3.5 million ($2.9m – $4.6m; 15% and 5% discount rate, respectively).

5.3.2 Western

Western brown requires additional conservation effort under most of the parameter choices

for the 2% p.a. growth target. For this taxon, and for eastern, we show two alternative

conservation scenarios, one emphasizing aerial 1080 (Fig. 4) and a second emphasizing

trapping (Fig. 5), simply to illustrate the financial impact of alternative ways to recover kiwi

populations.



Figure 4. Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for western

brown kiwi, mainly using aerial 1080 poisoning.

One conservation scenario mainly using aerial poisoning operations leads to high additional

annual costs, which may require as much as $1.3 million extra funding under the low-growth

parameter choices (Fig. 4). Under the best-guess parameter choices, the additional annual

costs are $495,000. Growth rates with this management regime are low and hence large areas

need to be managed to increase the population. In addition, these costs are incurred every 3

years.

With the low initial population parameter choice, 2% growth p.a. can be achieved by

increasing aerial poisoning but reducing sustained trapping, which results in a negligible

(nett) additional annual cost. This is indicated by comparing the green bar below the x-axis

line and the purple bar above it in the ‘2% Low initial population’ parameter choice.

Management under this parameter choice is much cheaper than under the ‘2% High initial

population’ parameter choice because with a low population a higher proportion of kiwi are

under regimes such as ONE and kohanga, and so the share of the population that needs

additional management is smaller than with a high population.



Figure 5. Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for western

brown kiwi, mainly using community trapping.

Figure 5 shows the estimated annual costs for an alternative allocation of kiwi to management

regimes which emphasises the use of kohanga kiwi and sustained trapping. With every choice

of parameters and conservation scenario, the additional annual costs are much lower than

those 1080 costs shown in Figure 4, because growth rates are higher under trapping (1.06, i.e.

6% p.a.) than aerial 1080 every 3 years (1.02, Table 2), and because communities mostly

volunteer their labour. Particularly for the low initial population parameter choice, placing

more birds in kohanga means the conservation target can be achieved with fewer birds under

trapping or aerial poisoning management. A nett annual cost saving of just under $300,000 is

the result. The other scenarios show additional annual costs of between $90,000 and

$554,000.

The present value of the additional costs using the best-guess parameter choices to achieve

the 2% p.a. growth target in the total 15-year period under the aerial 1080 conservation

scenario (Fig. 4) is $4.5 million ($3.8m – $5.7m; 15% and 5% discount rate, respectively).

The present value of the additional costs under the low-growth parameter choice is $11.8

million ($9.9m – $14.7m).

The present value of the additional costs using the best-guess parameter choices to achieve

the 2% p.a. growth target in the total 15-year period under the mainly-trapping scenario

(Fig. 5) is just over $842,000 ($713,000 – $1 million). The present value of the additional

costs under the low-growth parameter choice is $4.7 million ($3.6m – $5.6m).

5.3.3 Eastern

Eastern brown requires additional conservation effort under all scenarios to reach the 2% p.a.

growth target, and with the low growth parameter choice for the 0% p.a. growth target. The

estimate of additional annual cost compared with the status quo is shown in Fig. 6 for one

conservation scenario of allocating birds to management regimes, which emphasises aerial

poisoning operations.



Figure 6. Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for eastern

brown kiwi, primarily using aerial 1080.

Under this allocation, the 0% growth p.a. target under the low-growth parameter choice has

an additional annual cost of $1 million. The best-guess parameter choice for the 2% growth

p.a. target has an additional annual cost of 1.9 million, whereas the low-growth parameter

choice costs $3.4 million additional to current funding.

Figure 7 shows the additional annual costs under an alternative allocation of birds to

management regimes. In this conservation scenario, the kohanga kiwi and sustained trapping

and toxin regimes are cheaper than aerial poisoning operations.

Figure 7. Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for eastern

brown kiwi, primarily using trapping.



For the 0% growth p.a. target, the low-growth parameter choice carries an additional annual

cost of just under $427 000. Using best-guess parameter choices for the 2% growth p.a. target

has an additional annual cost of just over $322 000, and the low-growth parameter choice is

the most costly at $832 000 over the current expenditures.

Using mainly aerial 1080 (Fig. 6), the present value of the additional costs of the low-

growth parameter choice for the 0% p.a. growth target for the whole 15 years is $9.3 million

($7.8m – $11.6m; 15% and 5% discount rate, respectively). For the 2% growth p.a. target,

the present value of the additional costs under best-guess parameter choices is $17.6 million

($14.7m – $21.9m), and $31.6 million ($26.4m – $39.4m) under the low-growth parameter

choice.

The present value of the additional costs with the low-growth parameter choice for the 0%

growth target p.a. using mainly trapping (Fig. 7) for the whole 15 years is $2.6 million

($2.1m – $3.4m; 15% and 5% discount rate, respectively). For the 2% p.a. growth target, the

present value of the additional costs under the best-guess parameter choice is $2.8 million

($2.3m – $3.6m), and $7.2 million ($5.9m – $9.3m) under low-growth parameters.

5.3.4 Great spotted

Great spotted kiwi requires additional conservation effort under all parameter choices,

regardless of the growth target. The 2% p.a. growth target cannot be achieved under the low-

growth parameter choice because ONE is unlikely to be practical; kohanga space on islands is

zero or limited; trapping opportunities are limited by terrain and access, and it may be hard to

get 2% growth from aerial 1080 alone. In all viable scenarios, the emphasis is on aerial

poisoning operations because of the remote and rugged landscape that great spotted inhabit.

The estimate of additional annual cost compared to the status quo is shown in Figure 8.

Figure 8. Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for great

spotted. The 2% p.a. growth target cannot be achieved under the low growth parameter choice, and is marked

with a red cross.



For the 0% p.a. growth target, the best-guess parameter choice has an additional annual cost

of $1.5 million. The high initial population parameter choice carries the highest additional

annual cost of $2.1 million. For the 2% p.a. growth target, the best-guess parameter choice

has an additional annual cost of $4.2 million, and the high initial population parameter choice

has the highest additional annual cost of $5.5 million.

The present value of the additional costs of the best-guess parameter choice for the 0% p.a.

growth target for the whole 15 years is $17.5 million ($15m – $21.4m; 15% and 5% discount

rate, respectively), and for the high initial population parameter choice it is $23.8 million

($20.5m – $29.2m). For the 2% p.a. growth target, the present value of the 15-year additional

costs of the best-guess parameter choice is $37.6 million ($31.4m – $47m); for the high

initial population parameter choice it is $49.8 million ($41.6m – $62.1m).

5.3.5 Fiordland

Fiordland tokoeka require additional conservation effort under all parameter choices,

regardless of the growth target. The 2% p.a. growth target cannot be achieved with low-

growth parameters. In all viable scenarios, the emphasis is again on aerial poisoning

operations because of their remote and rugged habitat, and the sparseness of local

communities. Kohanga sites are remote and it will be difficult to locate and transfer surplus

kiwi to mainland sites. The estimate of additional annual cost compared to the status quo is

shown in Figure 9.

For the 0% p.a. growth target, the best-guess parameter choice has an additional annual cost

of just over $847,000. The low-growth parameter choice carries the highest additional annual

cost of $1.4 million. For the 2% p.a. growth target, the best-guess parameter choice has an

additional annual cost of $2.9 million, and the high-initial population parameter choice has

the highest additional annual cost of $3.8 million.

The present value of the additional costs of the best-guess parameter choice for the 0% p.a.

growth target for the whole 15 years is $7.8 million ($6.5m – $9.7m; 15% and 5% discount

rate, respectively), and for the low-growth parameter choice it is $13 million ($10.9m –

$16.1m). For the 2% p.a. growth target, the present value of the additional 15-year costs of

the best-guess parameter choice is $26.7 million ($22.3m – $33.2m); for the high initial

population parameter choice it is $34.8 million ($29.1m – $43.3m).



Figure 9 Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for Fiordland

tokoeka. The 2% p.a. growth target cannot be achieved under the low growth parameter choice, and is marked

with a red cross.

5.3.6 Rakiura

Rakiura tokoeka require additional conservation effort under all parameter choices, regardless

of the growth target. In all but two conservation scenarios, the emphasis is on poisoning using

bait stations. For the 2% p.a. growth target, two scenarios also make significant use of the

sustained trapping and poison regime. There are kohanga options such as Pearl, Codfish and

Big South Cape Islands, but the ecological impact of introducing Rakiura tokoeka would

have to be assessed carefully. The estimate of additional annual cost compared to the status

quo is shown in Figure 10.

Figure 10 Estimate of annual costs additional to the status quo to achieve 0% and 2% growth p.a. for Rakiura

tokoeka.



For the 0% p.a. growth target, with best-guess parameters there is an additional annual cost of

just under $250,000. With low-growth parameters, there is the highest additional annual cost

of just under $406,500. For the 2% p.a. growth target, the best-guess parameter choice has an

additional annual cost of just over $607,000, and the low-growth parameter choice has the

highest additional annual cost of just over $773,000.

The present value of the additional costs with best-guess parameter choices for the 0% p.a.

growth target for 15 years total is $2.3 million ($1.9m – $2.8m; 15% and 5% discount rate,

respectively), and with low-growth parameters it is $3.7 million ($3.1m – $4.6m). For the 2%

p.a. growth target, the present value of the additional 15-year costs with best-guess

parameters is $5.6 million ($4.7m – $6.9m); with low-growth parameters it is $7 million

($5.8m – $8.8m).

5.3.7 All kiwi taxa that require additional resources to achieve 0% or 2% p.a. growth

For all kiwi taxa that require additional resources to achieve 0% p.a. population growth, the

additional annual cost with best-guess parameters is $2.6 million. Under these parameters,

only great spotted kiwi and Fiordland and Rakiura tokoeka require additional conservation

effort. The low-growth rate parameter choice has the highest additional annual cost ($3.9m),

and the low initial population and the high growth parameter choices have the lowest

additional cost ($1.7m).

The present value (10% discount rate) of the additional, cumulative, 15-year cost of halting

decline for these three parameter choices (low growth rate, low initial population and high

growth rate) are, respectively, $27.5 million, $38.5 million, and $18 million.

To achieve the 2% p.a. growth target with best-guess parameters carries an additional annual

cost of $8.1 million. The low-growth parameter choice was not costed because the

conservation target cannot be achieved for Fiordland tokoeka and great spotted kiwi. The

parameter choice with the highest cost is ‘high initial population’ ($11.3m).

The present value of the additional cost with these three parameter choices are, respectively,

$73.5 million, $22.5m, and $102m.

6 Discussion

Mammalian predators are the key cause of kiwi declines and range limitation, and all

unmanaged populations on the New Zealand mainland are declining, albeit at different and

sometimes little known rates (McLennan et al. 1996; Holzapfel et al. 2008; Robertson et al.

2011). Protecting habitat without reducing predation will not recover kiwi. Discussions

between major kiwi recovery partners are required to decide where, when, how and by whom

populations should be managed.

Increasing the scale of cost-effective pest control is a clear requirement for kiwi recovery, as

it is for restoration of most other New Zealand biodiversity. Small or mid-sized accessible

populations that have most birds managed (Haast, rowi, little spotted, Coromandel,

Northland) are increasing most rapidly, whereas large, remote populations with few birds

managed (Rakiura, great spotted, Fiordland) are declining most rapidly. This shows the



benefit of past kiwi recovery focus on the most threatened taxa, due to a team effort of DOC,

K4K, conservation agencies such as Forest and Bird, corporate sponsors such as BNZ, and

many communities. If our input data are correct, the eastern brown kiwi is finely poised

between increase and decline (Fig. 11).

Figure 11. Relationship between estimated current growth rate p.a. (mean over 15 years) with ‘best-guess’

parameters and proportion of birds in each population managed, for all 10 kiwi taxa. The horizontal dashed line

shows rate = 1.0 at which populations do not grow. Populations above this line are estimated to be increasing;

those below it are declining.

While this report has by necessity presented more detail about community than DOC costs,

both (and other) parties will be needed if all kiwi are to be managed to achieve 2% growth

p.a. New kiwi conservation work can be done either by community groups or by DOC,

although they probably have different intrinsic strengths. Communities can trap more

cheaply if they use volunteer labour, while DOC is an experienced organiser of aerial 1080

drops. Research and taxon recovery planning are also key DOC roles. The inevitable funding

shortfall between current (even including the Budget 2015 boost) and required levels to

achieve 2% p.a. growth has to be sought from somewhere – Government, communities,

individuals or corporates of various kinds. Many options are possible.



6.1 Adequacy of input kiwi data

As with most birds in New Zealand and elsewhere, actual densities or total sizes of kiwi

populations are not known precisely. This apparent shortfall persists because there are no

cost-effective techniques for counting kiwi. Determining actual population sizes is probably

technically feasible but may consume most of the kiwi management budget, and so is poor

value for money. Trained dogs can find kiwi and there are some data about their success rate,

but it is an inefficient method unless densities are high (Robertson & Fraser 2009). Most

populations are monitored with call counts (Pierce & Westbrooke 2003), which index but do

not enumerate actual population size. There is increasing use of automated recorders that can

be placed in the field and analysed by computers for kiwi calls (Digby et al. 2013) but they

generally do not detect as many calls as human listeners and do not allow estimation of

numbers of different birds calling in an area. We suggest that not knowing actual population

sizes is no impediment to kiwi recovery, although obtaining reliable knowledge about how

changes in call rate indices relate to changes in actual kiwi numbers at different densities is

important to enable accurate reporting on conservation outcomes.

The most critical uncertainty in our models is growth rates associated with each of the key

regimes, but particularly with trapping and aerial (or ground) poisoning. Most of the

population growth rates we present have not been directly measured for each taxon. Further

clarification of these is clearly required. Surely the best opportunity for this is to monitor kiwi

numbers during actual management programmes using the major regimes, in an adaptive

management framework. Uncertainty will remain about outcomes until this and other

research are undertaken.

6.2 Kiwi modelling assumptions

We assume that population growth rates associated with each management regime do not

improve with time, but in practice they should, with new technologies, toxins, and disciplines

(e.g. revised or enforced ‘best practice’, pest management Standard Operating Procedures).

Other assumptions listed in 4.2.3 have varying reasonableness. In practice, some kiwi

dispersal outside managed areas is highly likely if the areas are small; preliminary estimates

of natal dispersal distances for eastern brown were at least 5 km, and it is unknown if

dispersal is density dependent (Basse & McLennan 2003), but distances were smaller in

Northland (Robertson et al. 2011).

6.3 Selecting growth scenarios and preferred management techniques

There will rarely be one ‘right answer’ about where or how to manage kiwi, especially if their

current distribution (the geographic range they occupy) is still large. The suggestions we

make in this report are just that; many alternatives are possible. We hope that the spreadsheet

tools developed during this project can be used in a dynamic and iterative way to support

decision-making.

Selecting where to manage kiwi can greatly affect costs. Applying trapping or aerial

poisoning to sites with high kiwi density will increase kiwi benefits for a given pest control



cost. However, we suggest that people should choose to manage areas with room for

population growth, to avoid carrying capacity (or K) effects. K will vary from site to site,

and may also be affected by the removal of competitors such as ship rats and hedgehogs

(Erinaceus europaeus).

Different pest control tools also have quite different outcomes for other biodiversity. For

example, adding 200 birds to kohanga at Cape Sanctuary now could relieve 1000 others from

requiring aerial 1080 to achieve the same kiwi outcome, but aerial 1080 would undoubtedly

have broader ecosystem benefits than increasing kohanga birds in this way. Note that having

100 birds in the Cape Sanctuary now is predicted to result in having 400+ kiwi there in 15

years. The same may be said of stoat trapping to benefit kiwi. This regime by itself may

protect other stoat-vulnerable taxa, such as whio (Hymenolaimus malacorhynchos)

(Whitehead et al. 2008) and takahe (Porphyrio hochstetteri) (Hegg et al. 2012), but few

others, especially if ship rats (Rattus rattus) increase after stoats (their main predator) are

reduced (Blackwell et al. 2003). DOC and community groups may therefore have different

management preferences, because they have different legal obligations, social contexts, and

probably skills, knowledge, and resources.

The comparison of management options for western (5.3.2) and eastern (5.3.3) browns

showed that with volunteer labour, trapping was cheaper than aerial 1080, but this trapping

targeted mustelids (mainly stoats) only, while aerial 1080 is also an effective tool against the

much more abundant ship rats and possums.

6.4 Community conservation and cost modelling

Given the many uncertainties in the cost data that we have used in this report, our resultant

estimates should be seen as preliminary, and should be updated as better information comes

to hand.

Regarding the cost estimates of community conservation, this study relies on the community-

reported data gathered by K4K. There are significant differences in the total cost and cost

structures for each taxon. It is possible that the survey questions for this novel reporting

exercise were not sufficiently clearly defined, leaving room for interpretation and thus

reporting errors. Examples are that community groups sometimes included largely irrelevant

(to kiwi) rat control costs with kiwi kohanga management, and that they were asked to

estimate the areas (in hectares) that were protected by stoat trapping grids, which is a difficult

calculation. Also, there was no application of a ‘best practice’ sieve on community data, so

that the very diverse trap networks and regimes were treated as having the same pest and kiwi

outcomes, and mean costs were used to estimate costs of future management.

K4K should develop its questionnaire to elicit more kiwi-specific community actions and

costs, and repeat the survey on a regular basis. In due course, the improved and repeated data

would provide K4K with better information to analyse how the funds it distributes are spent,

helping it to allocate its resources more effectively.

A tentative result from analysing the data, for instance, is that communities, like DOC, spend

more time and funds on administration, advocacy, and other expenditures than they do on

predator control. While these activities are undoubtedly necessary under the current realities

for communities’ funding (see next section), lowering these costs is likely to bring the total



cost of kiwi conservation down by some margin: on average, for every dollar spent on

supporting activities, 86 cents are spent on predator control, the main support for kiwi

populations. This calculation includes volunteered time, costed at ca $21 per hour (see Time

in App. 2).

The benefits of the research directions described below are therefore relevant not just for

kiwi, but also for the government purse. With better monitoring and awareness of areas where

kiwi can flourish, conservation efforts can be targeted to achieve a higher cost-effectiveness.

Improved techniques for predator control will lower costs and bring down the funding

required to maintain populations and conserve kiwi. Since kiwi are not the only species that

would benefit from such research efforts, the synergies with the conservation of other species

imply that overall conservation costs might be brought down significantly.

The cost modelling assumed that the DOC contribution to kiwi conservation is maintained at

current (2014/15) levels and that the new money granted in Budget 2015 for 2015/16 onward

is indeed additional funding and not used to replace existing budget streams such as the Kiwi

Sanctuary programme and Community Conservation Partnership Funding.

6.5 Additional funding required to halt declines and achieve 2% growth p.a.

Our preliminary analysis suggests that significant additional funding is required to achieve

either of the stretch conservation targets. For the scenarios we used, and assuming best-guess

input data, funding of around $2.6 million annually on top of current funding is needed for

the next 15 years to halt kiwi declines. To achieve 2% growth p.a. of all 10 taxa, additional

funding of around $8.1 million annually is needed for the same period.

The recently-announced new funding package for kiwi conservation in Budget 2015 has an

injection of $11.2 million over the next 4 years but in the fourth year and thereafter $6.8

million per annum will be available for kiwi conservation. This should allow stable

populations to be achieved, with a remaining shortfall of $1.3 million per annum to achieve

2% growth p.a. across the board.

These cost figures are minimum estimates for a number of reasons. First, trapping costs are

based on rates for contractors and community volunteers. Stronger involvement of DOC staff

will raise the labour costs by some margin. Second, according to our data, more extensive use

of aerial poisoning operations will raise costs significantly. Third, for reasons outlined in 5.1,

the costs of pest-fences were not included but these could become significant if large fence-

lengths were allocated entirely to kiwi recovery.

The ratio of indirect costs and costs for predator control was mentioned above. Indirect

activities allow community conservation groups to recruit volunteers and attract funding. In

the K4K questionnaire, communities reported on time and expenditures that are currently

funded, which on average were 44% of the total cost. Not all these funds are secure for long

periods of time, forcing communities to search continuously for new funding when other

sources run out.

This suggests that kiwi conservation costs might be reduced by structuring funding in such a

way that communities are under less pressure to pursue funding or contribute out of their own

pocket. Such a funding structure could take many forms. In the current situation, it may be



beneficial if seeking funding is undertaken strongly by one organisation, such as K4K, that

might more efficiently engage with (e.g. corporate) funders than individuals.

6.6 Priority research and monitoring

Research to clarify the taxonomic status of the actual or perceived taxonomic units that we

have referred to as ‘taxa’ of kiwi in this report is needed to guide where management effort

should be prioritised.

As discussed above, future management decision-making would be greatly helped by more

structured investigation into growth rates of different kiwi populations under the major pest

management regimes identified here. This requires effective population monitoring tools.

Research should continue on the reliability of call-count indices, including examining the

efficacy of using automatic recorders (and analysing recordings to find kiwi calls), and the

ratios between call counts and actual kiwi numbers at varying densities. Verifying that call

counts can accurately determine underlying population trends would greatly help instil

confidence that different management regimes could be evaluated in that way. Other means

of monitoring kiwi, including faecal DNA and acoustic recorders, should also be explored.

Improved control techniques are required for key mammal pests, particularly stoats, but also

ferrets, and feral cats. This control should include better lures and baits, better traps

(including multiple kill), optimal sowing rates for 1080, and new toxins. It is particularly

valuable at the moment for kiwi managers to support the registration for aerial distribution of

the toxin para-aminopropiophenone (PAPP), and the development of suitable kiwi-proof baits

for that purpose. Further research is also needed on the effectiveness of dog aversion training

(Dale et al. 2013).

More complete and accurate costing of kiwi recovery will depend on improving the quality of

cost data from communities, and on obtaining full kiwi management and monitoring costs

from DOC. These will frequently be complicated by the fact that management of one species

such as a kiwi taxon (e.g. by pest-fencing) sometimes targets many others as well, so that

determining what proportion of costs should be allocated to kiwi is at best very difficult.

7 Acknowledgements

We thank Rogan Colbourne (Department of Conservation) for conversations about kiwi

ecology and management. We also thank reviewers whose comments greatly improved

versions of this manuscript: Andrea Byrom, Mario Fernandez, Jennifer Germano, Suzie

Greenhalgh, Michelle Impey, John McLennan, Henrik Moller, Carol West and Roger Pech.

Thanks also to Cynthia Cripps and Anne Austin for help with formatting and editing

respectively. Finally we thank the hard-working community group members who supplied

cost and population data to K4K for this work, and Michelle Impey of K4K for facilitating

that.



8 References

Baker AJ, Daugherty CH, Colbourne RM, McLennan JA 1995. Flightless brown kiwis of

New Zealand possess extremely subdivided population structure and cryptic species

like small mammals. Proceedings of the National Academy of Sciences of the United

States of America 92: 8254–8258.

Basse B, McLennan JA 2003. Protected areas for kiwi in mainland forests of New Zealand:

how large should they be? New Zealand Journal of Ecology 27: 95–105.

Blackwell GL, Potter MA, McLennan JA, Minot EO 2003. The role of predators in ship rat

and house mouse population eruptions: drivers or passengers? Oikos 100: 601–613.

Brown MA, Stephens RTT, Peart R, Fedder B 2015. Vanishing nature: facing New Zealand's

biodiversity crisis. Environmental Defence Society, New Zealand.

Brown K, Urlich S 2005. Aerial 1080 operations to maximise biodiversity protection. DOC

Research and Development Series 216. Wellington, New Zealand, Department of

Conservation.

Burbidge ML, Colbourne RM, Robertson HA, Baker AJ 2003. Molecular and other

biological evidence supports recognition of at least three species of brown kiwi.

Conservation Genetics 4: 167–177.

Butler D, McLennan JA 1991. Kiwi Recovery Plan. Threatened Species Recovery Plan 2.

Wellington, New Zealand, Department of Conservation.

Colbourne R, Bassett S, Billing A, McCormack H, McLennan J, Nelson A, Robertson H

2005. The development of Operation Nest Egg as a tool in the conservation

management of kiwi. Science for Conservation 259. Wellington, New Zealand,

Department of Conservation.

Colbourne RM, Robertson HA 1997. Successful translocations of Little spotted kiwi (Apteryx

owenii) between offshore islands of New Zealand. Notornis 44: 253–258.

Dale AR, Statham S, Podlesnik CA, Elliffe D 2013. The acquisition and maintenance of dogs'

aversion responses to kiwi (Apteryx spp.) training stimuli across time and locations.

Applied Animal Behaviour Science 146: 107–111.

Digby A, Towsey M, Bell BD, Teal PD 2013. A practical comparison of manual and

autonomous methods for acoustic monitoring. Methods in Ecology and Evolution 4:

675–683.

Gillies R, McClellan R, Rate S 2013. Operation Nest Egg situation analysis. Unpublished

Wildlands Consultants Contract Report 2999.

Hegg D, Greaves G, Maxwell JM, MacKenzie DI, Jamieson IG 2012. Demography of takahe

(Porphyrio hochstetteri) in Fiordland: environmental factors and management affect

survival and breeding success. New Zealand Journal of Ecology 36: 75–89.



Herbert J, Daugherty CH 2002. Genetic variation, systematics and management of kiwi

(Apteryx spp.). In: Overmars F ed Some early 1990s studies in kiwi (Apteryx spp.)

genetics and management. Science and Research Internal report 191. Wellington, New

Zealand, Department of Conservation. Pp.10–33.

Holzapfel S, Robertson HA, McLennan JA, Sporle W, Hackwell K, Impey M 2008. Kiwi

(Apteryx spp.) recovery plan 2008–2018. Threatened Species Recovery Plan 60.

Wellington, New Zealand, Department of Conservation.

Jones BM 2006. Assessing the effectiveness of a Department of Conservation procedure for

training domestic dogs to avoid kiwi. Science for Conservation 267. Wellington, New

Zealand, Department of Conservation.

McLennan JA, Potter MA, Robertson HA, Wake GC, Colbourne R, Dew L, Joyce L,

McCann AJ, Miles J, Miller PJ, Reid J 1996. Role of predation in the decline of kiwi,

Apteryx spp, in New Zealand. New Zealand Journal of Ecology 20: 27–35.

Norbury G, Hutcheon A, Reardon J, Daigneault A. 2014. Pest fencing or pest trapping: A

bio-economic analysis of cost-effectiveness. Austral Ecology 39: 795–797.

Ornithological Society of New Zealand 2010. Checklist of the birds of New Zealand, Norfolk

and Macquarie islands, and the Ross Dependency, Antarctica.Wellington, New

Zealand, Te Papa Press.

PCE 2011. Evaluating the use of 1080: Predators, poisons and silent forests. Wellington, New

Zealand, Parliamentary Commissioner for the Environment.

PCE 2013. Evaluating the use of 1080: Predators, poisons and silent forests. Update report.

Wellington, New Zealand, Parliamentary Commissioner for the Environment.

Pierce, RJ, Westbrooke IM 2003. Call count responses of North Island brown kiwi to

different levels of predator control in Northland, New Zealand. Biological Conservation

109: 175–180.

Ramstad KM, Colbourne RM, Robertson HA, Allendorf FW, Daugherty CH 2013. Genetic

consequences of a century of protection: serial founder events and survival of the little

spotted kiwi (Apteryx owenii). Proceedings of the Royal Society B-Biological Sciences

280: 20130576. http://doi.org/10.1098/rspb.2013.0576.

Robertson HA, Colbourne RM, Graham PJ, Miller PJ, Pierce RJ 2011. Experimental

management of brown kiwi Apteryx mantelli in central Northland, New Zealand. Bird

Conservation International 21: 207–220.

Robertson HA, Colbourne RM, Nelson A, Westbrooke IM 2006. At what age should brown

kiwi (Apteryx mantelli) eggs be collected for artificial incubation? Notornis 53: 229–

232.

Robertson HA, Dowding JE, Elliott GP, Hitchmough RA, Miskelly CM, O'Donnell CFJ,

Powlesland RG, Sagar PM, Scofield RP, Taylor GA 2013. Conservation status of New

Zealand birds, 2012. New Zealand Threat Classification Series 4. Wellington, New

Zealand, Department of Conservation.



Robertson HA, Fraser JR 2009. Use of trained dogs to determine the age structure and

conservation status of kiwi Apteryx spp. populations. Biological Conservation

International 19: 121–129.

Robertson HA, de Monchy PJM 2012. Varied success from the landscape-scale management

of kiwi Apteryx spp. in five sanctuaries in New Zealand. Bird Conservation

International 22: 429–444.

Whitehead AL, Edge K-A, Smart AF, Hill GS, Willans MJ 2008. Large scale predator

control improves the productivity of a rare New Zealand riverine duck. Biological

Conservation 141: 2784–2794.


Appendix 1: Explanation of key terms in this report

Kiwi taxa (plural) and taxon (singular): A taxon (plural taxa) is a ‘group of organisms of any

taxonomic rank (e.g. family, genus or species)’ (Concise Oxford dictionary of zoology1992).

Currently, the different ‘kinds’ of kiwi are not all taxonomically described in scientific

literature, and it is possible that some will be determined to be of lesser status than

subspecies. In practice, all are currently regarded as ‘conservation management units’ and

we call them ‘taxa’ here for simplicity’s sake.

Management regime: A kind of management such as trapping, aerial poisoning or ONE that

is applied to kiwi populations to increase their numbers.

Population growth rates: Kiwi populations are subject to annual change, depending on nett

outcomes of births and immigration versus deaths and emigration. We express change rates

in two ways, either as say 2% p.a. (so that each year the population is 2% larger) or for

modelling purposes as 1.02. That is, if the population is 500, then a year later it will be 1.02 x

500 = 510. Declines are expressed either with that word (e.g. a 2% decline), or for modelling

purposes as 0.98. With a 2% decline, a population of 500 will 1 year later be 0.98 x 500 =

490.

Modelling parameters: The population modelling in this report works by having (for each

taxon) a start population size and then a certain whole-population growth rate that derives

from how the kiwi in it are subject to different management regimes, each with different

growth rates. These numbers are the key parameters we use for modelling. For example,

Table 2 shows that for Fiordland tokoeka, there are 500 kiwi subject to the kohanga regime,

and these birds have a growth rate of 1.05 (the population increases by 5% p.a.). There are

550 kiwi subject to trapping, and they grow at 1.012 (1.2% p.a.). There are 100 that get aerial

1080 each 3 years, and these grow at 1.02 (2% p.a.). However, the vast majority of Fiordland

tokoeka (11400) have no pest management and their rate of change is 0.984 (i.e. on average,

a 1.6% decline p.a.). The overall taxon change rate after 1 year is 0.988 (a 1.2% decline)

because vastly more birds get no management than get some management. However, the

start population and these growth rates are only estimates, and may be wrong in some regard

– too low or too high. To allow for this possible error, we also model variations (e.g. ±30%)

on the best-guess initial population, and on each of the best-guess growth rates. These

variations are referred to in the report as parameter choices.

Conservation scenarios: Combinations of management regimes that in aggregate achieve a

desired growth rate (e.g. 2%) target. For example, our modelling suggests (Table 5) that you

can achieve a 2% increase for western browns either by subjecting more kiwi to aerial 1080

or more kiwi to trapping. All of the seven management regimes can be used to derive a large

number of different scenarios, that all have different outcomes for the kiwi population, and

different costs.



Table 7 Key words used in this report. Note that examples of applications are in columns below the headings,

but that the table rows are not meaningful.

Kiwi taxa Management regimes

Example population growth rates

Example modelling parameter choices

Example conservation scenarios

Little spotted kiwi ONE 1.02 (i.e. a 2% increase per annum)

Best-guess initial population

Subject 800 kiwi to aerial 1080 instead of ‘do nothing’

Great spotted kiwi Kohanga or island marooning

0.98 (i.e. a 2% decline per annum)

Best-guess initial population minus 20%

Subject 500 kiwi to trapping rather than ‘do nothing’

Northland brown kiwi

Sustained trapping with occasional poisoning

1.016 (i.e. a 1.6% increase per annum)

Best-guess initial population plus 20%

Subject 500 kiwi to trapping and increase kohanga kiwi by 150 rather than do nothing

Coromandel brown kiwi

Aerial poisoning 0.985 (i.e. a 1.5% decline per annum)

Best-guess population growth rate under a management regime

Eastern brown kiwi Captive breeding Best-guess growth rate minus 30% (i.e. a low growth rate)

Western brown kiwi

Ground poisoning Best-guess growth rate plus 30% (i.e. a high growth rate)

Rowi ‘Do nothing’

Haast tokoeka

Rakiura tokoeka

Fiordland tokoeka



Appendix 2: Cost data and assumptions

All data

The full list of data and their sources is available on request.

Administration

Communities reported on both funded and volunteered hours spent on administration (see

Time).

Advocacy

It is difficult to determine the effectiveness of advocacy due to its overlap with predator

control (Pierce & Westbrooke 2003).

Communities reported on both funded and volunteered hours spent on advocacy (see Time).

Furthermore, the reported data include total cost spent on advocacy resources. From added

notes, it became clear that these funds are used for ongoing expenses as well as capital, such

as signs. Since the shares of each could not be established, all these costs are treated as

capital (see Equipment capital cost). This implies that the estimate for this cost item is

conservative.

Automated acoustic recorders

Communities reported on time spent setting up and analysing data from acoustic recorders

(see Time).

The recorders were assumed to be the standard model developed by DOC. These were treated

as capital (see Equipment capital cost).

Benefits to non-kiwi species

Several cost items in this study, notably fences, benefit other native species as much as kiwi.

Without data on the presence and abundance of these other species, however, there is no

objective means of allocating the cost to them or kiwi. This study therefore disregards fence

depreciation and maintenance in estimating the costs of kiwi conservation.

Biosecurity

Only Northland communities reported a sum for biosecurity (protecting islands from pest

reinvasion). Based on expert judgement, this cost was not transferred to other taxa.



Equipment capital cost

Equipment, such as quad bikes, 4×4s, traps, etc., is assumed to have a 10-year technical life,

so there is a depreciation cost of 10% per annum on the initial investment. It is assumed that

equipment was new at the start of the 15-year period, and that the depreciation costs start to

accumulate from the starting year.

The number of vehicles in Northland was converted to a per-hectare cost based on reported

area under management, which was then applied to other regions.

Communities reported primarily on the type and number of traps deployed. Prices found at

online vendors can be as low as NZ$ 10–15 for a Conibear trap (or similar) and as high as

NZ$185 for a Goodnature A24 trap. Where possible, a range of prices was used to produce a

low and a high cost estimate. In both cases, a further 15% bulk discount rate was applied to

allow for the possibility that online prices do not reflect actual prices.

For a low-cost estimate of bait stations, the model was assumed to be the Philproof Mini bait

station, whereas the high-cost model was assumed to be the Philproof Possum Large bait

station. A 15% bulk discount was applied to the lowest advertised price. Only Northland

communities reported on the sum of bait stations used. This was converted to the sum of

stations per hectare based on reported area under management, which was then applied to

other regions.

The impact of these sensitivity analyses around traps and bait stations on the overall costs for

conservation of each taxon is relatively minor, and in the final reporting averages are used.

Only Northland communities reported a number for other capital assets. The value of the

capital reported by the Tāwharanui Open Sanctuary was subtracted, because these assets

represent 98% of the total capital reported by Northland communities and therefore deemed

unrepresentative. The corrected capital value was converted to a per-hectare value based on

reported area under management, which was then applied to other regions.

Equipment operating cost

Only Northland communities reported on the costs of running their equipment. This was

converted to a per-hectare cost based on reported area under management, which was then

applied to other regions.

Fences

See Benefits to non-kiwi species.

Dog training

The effectiveness of dog training is a subject of debate (Dale et al. 2013), and cannot be seen

separately from wider advocacy activities.

Communities reported on funded and volunteer time spent on dog training (see Time).



Landscape-level toxin campaigns (aerial 1080, ground-based 1080)

For this study, expert knowledge was used to incorporate bird distributions in calculations of

bird density. Bird density and numbers were used to approximate the area over which to

apply aerial poisoning operations.

In its report on the cost-effectiveness of aerial 1080, the Parliamentary Commissioner for the

Environment (PCE 2011) notes that the per-hectare cost of an aerial 1080 campaign is

between NZ$12 to NZ$16, with an additional NZ$ 1 per hectare cost for post-campaign

monitoring. Sporle (2008) suggests the cost of a 1080 campaign is NZ$17 per hectare.

In this report, a cost of $17 per hectare was used for aerial 1080 operations. If all transaction

costs (community engagement, planning, etc) are considered, the cost of aerial 1080

operations may be higher.

A cycle of one campaign every three years is assumed, except in the status quo and 0%

growth scenarios for great spotted.

For Rakiura tokoeka, the deployment of bait stations with 1080 was deemed more appropriate

than aerial distribution. DOC data suggests a cost of between $25 and $43. An average cost

of $30 was assumed as was a 3-year cycle.

Monitoring

Communities reported on both funded and volunteered hours spent on monitoring (see

Automated acoustic recorders and Time).

Operation Nest Egg (ONE)

For this conservation instrument, the reported cost per released juvenile was taken from

Gillies et al. (2013; Table 9 – Juvenile released). If taxons benefit from multiple ONE

facilities, the mean was taken. In the case of Northland brown kiwi, expert-based judgement

was used to determine an average cost for the ONE facilities concerned, which operate very

differently and have different costs per juvenile released.

Time

The conservation communities provided data on funded and volunteer hours. For this study,

funded hours are assumed to be contracted out to professionals, at a rate of NZ$ 30 per hour

for toxin application, trapping, animal control, administration and monitoring. This is in line

with guidelines for funding applications to Kiwis for kiwi.

Contracted hours for kiwi tracking dogs are valued at an hourly rate of NZ$45, as

recommended by guidelines for funding applications to Kiwis for kiwi. This rate was also

applied to contracted hours for dog kiwi aversion training.



The value of volunteered hours is approximated by the median wage rate. The median hourly

earnings for New Zealand in 2014 is NZ$21.94 (Statistics NZ: New Zealand Income Survey

for June 2014).

We have not included activities that were clearly marked as DOC operations, but DOC staff

are likely to have higher hourly rates ($115 per hour has been suggested). For labour-

intensive conservation actions, the involvement of DOC staff rather than contractors and

volunteers will raise the cost of kiwi conservation by up to 3-5 times.

Toxins (ground-level application)

There is a large diversity of toxins for ground-level application, and each comes with its own

guidelines. Communities reported on the area collectively treated with toxins other than 1080

and brodifacoum, but the data did not allow explicit assessment of the use of each toxin.

Only Northland communities reported an expense for toxins that were not otherwise included

in the reporting template. This was converted to a per-hectare cost based on reported area

under management, which was then applied to other regions.

Only Northland communities reported the number of bait stations used. This was converted to

a per-hectare cost based on reported area ‘treated with other toxins’, which was then applied

to other regions.

Translocations

A full translocation consists of multiple steps, including time spent collecting suitable birds,

transport to and from islands, and transport across the mainland (although Air New Zealand

currently donates cargo space). The cost range depends on the level of involvement of DOC

staff (Hugh Robertson, 2014, pers. comm.) and was not included in light of the lack of

appropriate data.

Trapping

See Equipment capital cost and Time. The data are available upon request.

If communities did not specify the ‘other traps’ by type, the number of ‘other’ traps was

divided equally among the trap types reported (e.g., 50% Conibears, 50% DOC200s).

saving a national icon: preliminary estimation of the ......suzie greenhalgh portfolio leader -...

Documents