Bat fauna monitoring before and during operation phase of the wind farm Danilo in Croatia

Dina Rnjak, mag. oecol. et prot. nat. Vida Zrnčid, mag. oecol. et prot. nat.

Goran Rnjak, bacc. ing. aedif.

Nikola Hanžek, mag. oecol. et prot. nat.

Dr. sc. Marin Grgurev, Gekom d.o.o.

Geonatura Ltd. Consultancy in Nature Protection

• among others, a team specialized in bat fauna research

- impact assessments, pre- and post-construction monitoring, mitigation measures design for bats

From 2013: - baseline surveys for 6 WF in Croatia and 1 in Bosnia and Herzegovina - one-year post-construction monitoring at 2 WF in Croatia

Survey design and methodology

national guidelines (Ministry of Environmental Protection, Physical

Planning and Construction and APO Ltd. 2010)

taking also into consideration international guidelines of UNEP/EUROBATS

depending on a project, it can include

• periodic and continuous bat detector monitoring

• investigation of potential and monitoring of important roost sites

• mist-netting

• searching for bat fatalities

WF Danilo

• RP Global Danilo Ltd.

• Šibenik-Knin County in Croatia

• locations Bubrig (10 WT) and Velika Glava (9 WT)

• Mediterranean karst region

• dry and rocky pastures which have mostly turned into shrubs

Total installed capacity: 43.7 MW Turbine type: Enercon E-82 Number of WT: 19 Tower height: 78 m Rotor diameter: 82 m

Given the absence of a one-year bat fauna research during the environmental impact assessment (EIA) (there was no legal obligation for this type of research until 2009), the first year of monitoring was carried out through a detailed one-year preliminary study of bat populations in the wider area around the planned construction site

One-year bat monitoring before operation phase

2013 2014

ACTIVITY Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

Collection and analysis

of existing data

- spatial data

- literature data

- survey design

Field surveys

Periodic bat

detector monitoring

Investigation of

potential and

important roost

sites

Mist netting

Processing and analysis

of collected data

Periodic bat detector monitoring

• to determine present bat species and their activity

• main transects through WT locations + control transects in the lowland which included other types of habitats

• when highest activity can be expected (1-2 h after Sunset)

• determined whether bats were passing through or foraging

• temperature, humidity, wind speed were measured at the beginning and end of each survey

Investigation of potential and monitoring of important roost sites • caves, tunnels, buildings etc. in the 5 km

buffer area

• locations, type of roost, species abundance and composition

• microclimatic conditions measured inside and outside potential bat roosts

Mist netting

• in order to identify present species, as well as their sex, age and reproductive status

Processing and analysis of collected data

• echolocation/sound analysis

• GIS analysis

• bat activity analysis - spatial and temporal distribution

Site-specific assessment

possible critical periods with risk of bat fatalities

species at highest risk for collision and/or barotrauma

possible need for mitigation measures

Results • 13 bat species, along with phonic species groups

• June 2013 - gravid females of P. kuhlii and Pl. macrobullaris by mist netting

• P. kuhlii and H. savii - most frequently use the Project area and potentially most vulnerable

• low bat activity level during early spring, mid-summer and late autumn

• high bat activity during seasonal migrations

May - 74,9 contacts/h Velika Glava - 111,1 contacts/h September - 44,2 contacts/h

• 24 underground sites surveyed (the deepest 104 m and the longest 117 m)

- in 15 no bat presence was recorded, up to 10 bats were recorded in 6 caves

• EUROBATS important underground sites (Natura 2000 sites) monitored regularly:

1. Škarin Samograd - Mn. schreibersii, M. capaccinii, M. myotis/blythii, R. euryale 2. Dobra voda - M. emarginatus, R. ferrumequinum 3. Stražbenica - M. emarginatus, R. euryale, R. ferrumequinum

One-year bat monitoring in operation phase

2014 2015

ACTIVITY Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

Field surveys

Searching for bat

fatalities

Periodic bat

detector

monitoring

Continuous bat

detector

monitoring

Monitoring of

important roost

sites

Processing and

analysis of collected

data

Searching for bat fatalities within 70 m radius of WTs

• approx. 45 minutes/man/WT with max. time intervals of 15 days (8-12)

• found bat carcass:

o photo documentation

o position (coordinates, terrain visibility, closest WT, distance from the WT)

o state of the carcass (fresh, a few days old etc.), type of injury

o taxonomic affiliation, sex and age (if possible)

• taking into account ground cover and terrain morphology visibility classes were determined:

1. Areas of high visibility - plateaus, slopes, roads

2. Areas of low visibility - shrubs and high grass

- not searched given the size of bat carcasses and quick changes in appearance

(from fresh carcass to skeleton)

WT II-3: Percentage of area searched: 25,1 % Percentage of weighted area searched (expected density of bat carcasses on the ground): 52,4 %

Testing the carcass removal rate

• setting up 25 dead mice on search plots in May and September 2014

• monitoring the speed of their disappearance to estimate removal rate and then annual bat mortality

• calculated average time for carcass persistence: 8,6 days

Estimation od annual bat mortality

• estimation of the real number of bat fatalities at the wind farm

• “carcass package" Korner-Nievergelt et al. 2015 (based on Huso 2010 and Etterson 2013)

the number of found carcasses/injured individuals

time intervals between two searches

carcass removal rate

searcher efficiency (100%)

percentage of area searched in the 70 m radius

variable probability of finding carcasses regarding the distance from WT

Periodic bat detector monitoring • main transects defined during the baseline survey (February - November)

when highest activity can be expected

• microclimate conditions measured at the beginning and end of each survey

Monitoring of important roost sites

EUROBATS important underground sites (within Natura 2000 sites) were monitored during maternity season: 1. Škarin Samograd cave 2. Dobra voda 3. Stražbenica cave

Continuous bat detector monitoring

• set up on a weather mast through full cycle of bat activity

• temporal distribution, bat activity index in correlation to weather conditions (air temperature, wind speed)

Bat activity analysis

• BatSound, Sonobat, BatExplorer and Kaleidoscope software

• bat species

• activity index (corrected with species detectability), activity type, spatial and temporal distribution

• correlation to microclimatic conditions (based on the data on wind speed and temperature from a weather mast given by RP Global Ltd.)

Results

# Bat species IUCN1

Mediterr.

IUCN1

HR

HD2

92/43

EEC

Status

Croatia20103 Collision risk

Percentage of bat fatalities

(min-max)6

1 Hypsugo savii LC - IV Very common x 29,4 - 30,9 %

2 Miniopterus schreibersii NT EN II, IV Common x -

3 Myotis bechsteinii NT VU II, IV Common -

4 Myotis capaccinii VU EN II, IV Common -

5 Myotis emarginatus LC NT II, IV Very common -

6 Myotis myotis LC NT II,IV Common -

7 Myotis blythii NT - II,IV Very common -

8 Nyctalus leisleri LC NT IV Common x 5,9 - 7,4 %

9 Nyctalus noctula LC - IV Very common x -

10 Pipistrellus kuhlii LC - IV Very common x 35,3 - 45,6 %

11 Pipistrellus nathusii LC - IV Common x 13,2 - 23,5 %

12 Pipistrellus pipistrellus LC - IV Common x 1,5 - 11,8 %

13 Pipistrellus pygmaeus LC - IV Very common x 1,5 - 11,8 %

14 Plecotus kolombatovici LC DD IV Common -

15 Plecotus macrobullaris NT DD IV Common -

16 Rhinolophus blasii NT VU II, IV Rare -

17 Rhinolophus euryale VU VU II, IV Common -

18 Rhinolophus ferrumequinum

NT NT II, IV Very common -

19 Rhinolophus hipposideros NT NT II, IV Very common -

20 Tadarida teniotis LC - IV Common x 1,5 - 2,9 %

21 Vespertilio murinus LC - IV Rare x 1,5 - 2,9 %

• periodic bat activity monitoring and monitoring of important underground sites in 2014 - in compliance with the results of bat monitoring in 2013

• bats use the Project area mostly during seasonal migrations (late spring, early autumn)

• higher activity at Velika Glava

• continuous bat detector monitoring - higher activity also in June and August

• during autumn, bat activity gradually decreases, despite suitable weather observed until the end of November

February 2014- March 2015

• 68 bat fatalities at 18 out of 19 WT

• June, July, August, September and October 2014

• March – April - low bat activity and a low risk of bat fatalities

• May - bat activity increased, but smaller number of bat fatalities was found (foraging at lower heights)

• June - first bats fatalities were recorded (pregnant females)

• July - bat activity decreased (late pregnancy and first week after birth)

• end of July - first fatalities were again found, higher activity (youngs start to fly)

• August - October - number of bat fatalities increased (autumn migrations)

• November - bat activity almost absent, no fatalities found (the end of autumn migrations)

Correlation to weather conditions

The need for implementation of protection measures for bats fauna during WF operation is correlated with the level of their activity

1. in space (e.g. habitat type),

2. time (e.g. time of the year, night/day)

3. in relation to weather conditions (ambient temperature, wind speed, precipitation).

Key factor - A substantial proportion of bat fatalities occur during relatively low wind speed and temperature above 10°C.

90% recorded bat activity Max. wind speed

based on avg. 10-min values

(m/s)

Min. temperature

based on avg. 10-min values

(°C)

June 2014 4,2 16,8

July 2014 5,6 17,8

August 2014 5,1 18,4

September 2014 5,3 14,0

October 2014 3,6 15,0

Conclusion

• detailed bat surveys as part of EIA are neccesary to assess possible impacts on resident and migrating bats and collision risk

• bat activity between sites and species wind tolerance may significantly differ

• effective thresholds for cut-in wind speed and temperature should be determined on a case-by-case basis

• with good understanding of spatial and temporal variability of bat activity in relation to environmental conditions, optimal site-specific mitigation measures can be determined - minimizing the number of bat fatalities as well as power loss in energy production at the same time

As well as during previous surveys at WF Danilo, periodic and continuous bat activity monitoring are being continued as well as carcass searches