Identifying Coastal Forest Merlin (Falco columbarius suckleyi) Breeding Habitat Using

Geographical Information Systems

Christopher M. Talley Western Washington University

Abstract. The Coastal Forest Merlin (Falco columbarius suckleyi) natural breeding habitat

has traditionally been located in the temperate rainforests of the Pacific Northwest of the United

States and Canada. The natural habitat has experienced a significant reduction in habitat quantity

due to anthropogenic influence over the last 150 years. Despite the reduction in their traditional

habitat the Merlin has been able adjust to changes in habitat and expand their population. During

each breeding season from 1986 to 2013, nest sites and home ranges were geographically located

for a population of Coastal Forest Merlin (Falco columbarius suckleyi) in an 116,660 km² study

area that encompassed areas of Northwestern Washington State and Southeastern and the Central

Interior of British Columbia, Canada. Geographical Information Systems (GIS) and satellite

imagery were used to determine and compare the amount, distribution, and configuration of

several key habitat variables within 8km circular plots centered on known nest sites and random

control sites. The plot size utilized for analysis was based on the observed distribution and

behavioral characteristics of Merlins within the study area Analysis demonstrated that complex

habitat edge configuration, greater spatial heterogeneity, and higher amounts of habitat richness

were the most significant Merlin breeding habitat variables. The results of analysis are intended

for landscape scale systematic analysis of breeding habitat variables, demographic assessments,

and to guide recovery and management decisions.

Key Words: Coastal Forest Merlin; Falco columbarius suckleyi; Raptors; Geographical

Information Systems, habitat use; landscape ecology.

INTRODUCTION

In 2012, the Coastal Forest Merlin was listed in Washington State as a species of

concern based on the declining amounts of suitable habitat throughout their range, declining

population trends, and lack of existing regulatory methods to protect the species (WDRW, 2012).

Habitat characteristics such as land cover, land use, vegetative composition, and spatial

configuration are key elements that influence wildlife breeding success and species evolution

(Rodiek & Bolan, 1991). In order to comprehensively understand the importance of land cover

characteristics on a species viability and development, it is necessary to effectively model

wildlife habitat in terms of spatial and land cover characteristics (Turner & Gardner, 1991). With

increased importance being placed on spatial dynamics in relation to landscape ecology and

species evolution, it important to utilize modeling methods that consider variety of

environmental variables to produce relevant habitat models (Tutle. Et. al, 2006). Quantifying

information about habitat characteristics such density and distribution over large geographical

areas by field surveys can be expensive, time consuming, and impractical. To complete this task,

computer derived habitat models created using Geographical Information Systems (GIS) can be

used effectively to depict the vegetative and groundcover characteristics of a large study area

1

(Lillesand and Kiefer, 1987). Geographic Information Systems significantly increase

productivity by allowing researchers to efficiently survey and analyze many aspects of wildlife

ecology without the spatial and temporal limitations of traditional methods (Shaw & Atkinson,

1990).

The purpose of this project was to create a GIS based landscape level habitat model to

evaluate breeding habitat characteristics of the Coastal Forest Merlin in a study area which

comprises areas of Northwestern Washington State and Southwestern British Columbia. The

model building process consisted of creating a digital database by compiling and interfacing

comprehensive digital vegetation and land cover data generated from Landsat 7 ETM+

multispectral data satellite imagery, vector and raster based political and environmental data

created by various agencies, and field gathered groundcover data.

The objectives of this study were to: 1) determine the quantity and spatial distribution of

different of habitat variables, 2) evaluate the relative importance of habitat variables on Merlin

distribution and abundance, and 3) investigate species demographics and density in different

habitat types. The information generated by this project is designed to provide knowledge and

guidance to help inform scientists, policy makers, and property owners in making prudent

resource management decisions that will help retain valuable habitat for the continued

reproductive success for the Coastal Forest Merlin.

Study Area

The habitat modeling described in

this report was conducted on an 116,660

km² (11,666,048 ha) study area spread

over portions of Northwestern Washington

State and Southeastern British Columbia

Canada. The study area was bounded

approximately by the geographical

coordinates of 128º W to 120 º W

longitude, and 46º N to 55º N latitude. The

land forms consist of highly developed

floodplains and coastal lowlands, heavily

forested and rugged coastal mountainous

regions, and drier inland moderate

elevation plateaus.

Land ownership is a broad mix of

public, private, and tribal owned lands.

The study area occupies parts of 4 distinct

ecologically and geographically defined

level III ecoregions; 1) the Puget Trough-

Georgia Basin, 2) the Pacific Northwest

coast., 3) the central interior of British

Columbia, and 4) North Cascade and

2

Pacific range (Nature Conservancy,2006).

The Puget Trough- Georgia

Basin ecoregion occupies a long narrow

continental glacial trough that consists

of many islands, peninsulas, and inlets.

Elevations in the area range from sea

level to 750-1000 meters in the foothills.

The area is characterized by a mild

maritime climate with mild, wet winters.

Summers are fairly warm and dry and

often overcast. Mean January

temperature is 4° C and mean July

temperature is 18° C. Precipitation,

falling primarily as rain, averages 100

cm per year. The Olympic Mountains

created rain shadow areas that include

the northeast corner of the Olympic

Peninsula, Whidbey Island, and the San

Juan Islands. The annual precipitation

tends to be lower in these areas

averaging 40 to 75 cm.. Rainfall is

higher in the foothills due to the

orographic lift created by the Cascade

Mountains and averages 150-200 cm a

year.

The natural landscape consisted of thick coniferous forests that grew on areas consisting

of glacial moraines, floodplains, and river terraces. Douglas-fir (Pseudotsuga menziesii), western

hemlock (Tsuga heterophylla), western red cedar (Thuja plicata), and grand fir (Abies grandis) are the predominate species in the upland forests, while black cottonwood (Populus

trichocarpa), red alder (Alnus rubra), and big leaf maple (Acer macrophyllum) are the common

forest elements in riparian areas.

The Pacific Northwest Coast region includes the coastal Ranges of Northwestern

Washington State and Vancouver Island. The region has landforms that consist of beaches, low

marine terraces, sand dunes, and spits in the marine areas, headlands, high marine terraces, and

low mountains in the uplands, and the lower portions of the Olympic Mountains up to around

1200m in elevation. The Coast Range’s climate is influenced by cool, moist air from the ocean.

Mean January temperature is 6° C and mean July temperature is 12° C. Precipitation falls mainly

as rain at the lower elevations and averages 150- 250 cm a year, with some areas receiving

upward of 500 cm of rain a year. The coastal lowlands and low mountains are dominated Mature

forest consist primarily of Coast Douglas Fir (Pseudotsuga menziesii var. menziesii), western red

cedar, western hemlock, and Douglas fir. Pacific silver fir (Abies amabilis) and mountain

3

Hemlock (Tsuga mertensiana) are the common forest elements at higher elevations. Wetter

and riparian areas supports red alder, black cottonwood, western red cedar, and big leaf maple.

The understory typically contains salmonberry (Rubus spectabilis), salal (Gaultheria

shallon), western sword fern (Polystichum munitum), vine maple, and Oregon grape (Mahonia

aquifolium).

The Cascade Mountains and Pacific range region is primary high mountainous area in the

study area consists. The alpine areas consist of glaciated mountain terrain with elevations up to

2000m, and several large composite volcanoes that rise to over 3000m. The region receives high

amounts of precipitation from 150 to 400 cm a year as rain or snow. The higher elevations can be

covered by as much as 6 m of snow in the winter.

The vegetation in the region is highly diverse. The mountainous areas have a moist,

temperate climate that supports an extensive and highly productive coniferous forest that is

intensively managed for commercial logging. At lower elevations, Douglas-fir, western hemlock,

western red cedar, big leaf maple, and red alder are typical. At mid elevations, Pacific silver fir,

mountain hemlock, noble fir (Abies procera), and lodgepole pine (Pinus contorta) are the

common tree species. A mosaic of mountain hemlock, Pacific silver fir, yellow cedar, and

subalpine parklands occurs at higher elevations. Disturbed areas can be lined with Sitka alder or

vine maple.

The interior of British Columbia ecoregion occupies a plateau in the central portion of the

province with long forested sections into the valley bottoms of mountainous areas to the north,

east, and west. Elevations range from 750 to 1500 m. Several major lakes and rivers are located

in this zone. The area experiences extremes of temperature; the summers are short with warm

temperatures that can reach a high of 30 degrees Celsius. Winters can reach temperatures of -10

degrees C, with extremes sometimes at -40 degrees C.

The rolling landscape of the Sub-Boreal zone is covered in primarily coniferous forest.

Pioneer species include the trembling aspen (Populus tremuloides) and paper birch (Betula

papyrifera) in the uplands. The dominant coniferous species are hybrid white spruce (Picea

glauca), subalpine fir (Abies lasiocarpa), and occasionally, black spruce (Picea mariana), along

with lodgepole pine and occasionally Douglas-fir. Primary components of the understory

include; Queen’s Cup (Clintonia uniflora), Devil’s club (Oplopanax horridus), Sitka alder

(Alnus viridis), and multiple species of wild berries.

Focal Species

The Coastal Forest Merlin (Falco columbarius suckleyi) is one of three North

American sub-species of Merlin Falcon. The sub-species inhabits the Pacific-Northwest

temperate coastal rainforests. They tend to nest adjacent to rivers and water bodies near forest

openings or edges (Johnsgard, 1990). The relatively small yet sturdy bird uses its speed and

agility to prey on small song and shorebirds, insects, and small mammals (Cade, 1982). Merlins

use the same general area year after year for breeding, but not necessarily the same actual site,

particularly if young were fledged the previous year (Brown & Amadon, 1968). Nest are almost

exclusively is located in high in mature conifer trees with a complex canopy structure (Sohdi et

4

al., 1993). The Merlin can occupy elevations that range from sea level to near the tree line.

Historically this subspecies has preferred breeding and foraging sites that have complex forest

structure common to late seral stage conifer forest. The subspecies native natural habitat of

temperate rainforest has experienced significant decline in quantity and continuity due to

anthropogenic influence over the last 150 years (Stillman, R.C., personal communication, August

26, 2014). Their conservation status varies by jurisdiction In Washington State they are classified

as a Species of Concern and as a State Candidate Species (WDFW, 2013). In Canada, the Merlin

is considered not at risk (COSEWIC, 2009). In light of the decline in natural habitat, the Merlin

is highly adaptable in terms of habitat selection and has proven successful while occupying nests

in more densely populated areas. Although the breed prefers mature conifer trees for its nest

sites, they have the ability to thrive in areas of intense human activity and forage in areas with a

high level of habitat class variability.

METHODS

Field Methods

The study area was subject to a long term demographic study conducted by the Merlin

Falcon Foundation from 1986-2013 during which Coastal Forest Merlin were non-invasively

monitored to establish distribution and relative abundance of the population (Drummond &

Stillman, 2014). The systematic searches occurred while assessing behavior and reproductive

status during each breeding season (roughly mid/late Feb to early August). During field surveys,

each nest site observation of a territorial resident of the population was documented and assigned

a unique identification code. Relevant nest site microhabitat, geographical, and environmental

characteristics were integrated with the breeding data and nest location information (Drummond

& Stillman, 2014)

In order to develop a multivariate set of habitat characteristics designed to analyze avian

associations and habitat use, a GIS dataset defining Merlin activity centers, as well as relevant

geographic and environmental data, were created using ESRI Arcmap 10.2 (ESRI 2014. ArcGIS

Desktop: Release 10. 2. Redlands, CA: Environmental Systems Research Institute). A GIS vector

geospatial shapefile for Merlin nest sites was creating by importing and geo-referenced

coordinate data collected during field surveys. To calculate the distance to steams and open

water from each nest site the spatial join tool was used to combine vector stream and water body

data from the 2010 Natural Resources Canada National Hydro Network (NHN) and the 2014

USGS National Hydrography Dataset (NHD) with the nest site coordinate data. The distance

from nest sites to streams and open water was determined using the near function in the analysis

toolbox. Stream density was calculating using the line density function of the spatial analysis

toolbox. Topographic surface features were derived from a 2010 United States Geological

Survey 10 m resolution digital elevation model that covered the entire study area. The elevation

of the center point of analysis plots was extracted from a USGS using the extract values to points

function of the spatial analysis toolbox.

Land Cover Classification

5

National Land Cover Database 2006 (NLDC, 2006) land cover/ land use maps developed

by the Mutli Resolution Land Characteristics Consortium (MRLCC) and Natural Resources

Canada Earth Observation for Sustainable Development of Forests (EOSD) were used to create a

land cover map of the study area. The raster based maps were generated from medium resolution

(30 m²) geometrically rectified Landsat 7 Thematic Mapper (TM) satellite imagery collected in

2006. The maps were created by processing the satellite imagery using an unsupervised

classification and regression analysis (Franklin & Mulder, 2002; Lillesand, & Kiefer, 2000).

Additional data used to develop the groundcover analysis included high resolution color aerial

photographs, digital elevation models, and field data obtained from the U.S. Forest Service, and

Natural Resources Canada (O'Neil et al., 2006; Wulder & Nelson, 2002).

The derived data from NOAA and ESOD was combined and processed using ESRI

ArcMap 10.2 to create a 9 group habitat class map for the study area. The designated habitat

classes used for analysis were based on field assessments of land cover characteristics and

observed Merlin behavior, then correlated with the National Land Cover Database (NLCD)

classification system. (Drummond & Stillman, 2014; NLCD, 2006) See appendix A for

comprehensive descriptions of the habitat classes. In order to increase the accuracy of the

analysis, a mask was created to eliminate areas of open water, and areas above 1500 m in

elevation, the observed upper elevation limits of Merlin activity. The accuracy of the classified

image was verified using field gathered vegetation plot data as well as field data obtained from

United States Bureau of Land Management (BLM), and the British Columbia Ministry of Forests

(BC MOF). The classified image was resampled to a 25m² cell size in an effort to simplify

analysis rather than increase the accuracy. Prior to measuring landscape patterns, the spatial

analysis filter tool of ArcMap was used to perform low option 3x3 smoothing procedure of the

raster land cover map. The purpose of this step was to reduce the significance of anomalous cells

giving the map a greater relevance to natural landscape patterns.

Two types of metrics were analyzed to help define Merlin habitat: landscape composition

and landscape configuration (McGarigal & Marks, 1995). Composition refers to the abundance

of a land cover type or attribute, whereas configuration describes the spatial arrangement of

patches or features. Landscape composition characteristics of the habitat class map were

measured using the class metrics function of FRAGSTATS v4 spatial pattern analysis program

(McGarigal, Cushman, & Ene, 2012). Landscape pattern configuration variables for the study

were measured using the patch metrics function of FRAGSTATS.

Landscape scale habitat pattern characteristics were determined for areas within an 8km

radius (201.06 km²) plots centered on known nest sites. This area represents the observed extents

of Merlin's home range activity (Drummond & Stillman, 2014). 9 variables were utilized to

analyze habitat quality; 1) the total amount and percent of land cover contained in each of the 9

habitat classes, 2) patch density, a index of spatial heterogeneity; 3) the density of habitat edge

(m/ha), 4) the number of different habitat types within each 25m² cell defined habitat richness

(ha), 5) stream density (m/ha), 6) distance to riparian areas, 7) patch shape which indicates the

geometric complexity of the patch, 8) the amount of impervious surfaces, and 9) the percentage

of forest canopy cover.

6

Standardized residuals of each variable were tested for normality. Independent sample t-

tests were employed to test the distribution of habitat variables between “used” habitat plots and

“random” plots. Additional analysis of nest site density and habitat associations was conducted

using Pearson correlation coefficient testing. Statistical analysis testing was conducted using

SAS 9.3 (SAS Institute, Cary NC). Due to the conservation status of the Pacific Forest Merlin, an

alpha level of <0.05 was selected for all tests of significance (WDFW, 2013).

Ground Plots

Habitat microhabitat structure and configuration play a vital role in a land bird’s selection

of breeding territory and nest site (James & Shugart, 1970; Block & Brennan, 1993). In an effort

to depict the full spectrum of vegetative and physiographic characteristics reference 238

vegetation plots were collected during field assessments. The 25 m radius (0.196 ha) vegetation

plots were delineated and surveyed near Coastal Forest Merlin nest sites during the study period.

The classes defined in the process were designed to represent the various types habitat Coastal

Forest Merlin encounter in association with different aspects of their behavior.

RESULTS

Land Cover Characteristics

Analysis of habitat landscape configuration and composition was conducted on 70

individual non overlapping 8km radius (201.06 km²) home range plots centered on known

Merlin nest sites, and 33 randomly generated (Figure 3). In the 70 used home range plots the

largest habitat classes in terms of total area were conifer forest which comprised 3108.46 km²/

58.42 %; followed by; mixed forest 486.71 km²/ 9.15 %; shrub/scrub 412.90 km² / 7.76%,

agriculture 362.43 km²/ 6.35%, and developed low intensity 337.92 km²/ 6.14 %. The rest of the

habitat classes individually made up less than 5% of the groundcover in the analyzed regions

each (Table 1). Bare land constituted 0.38% of the land cover and was eliminated from analysis.

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Agriculture Deciduous

Forest

Developed Open

Space

Evergreen Forest High Intensity

Developed

Low Intensity

Developed

Medium Intensity

Developed

Mixed Forest Scrub/Shrub

Habitat Class

Sq

uare

Kil

om

ete

rs

Figure 3. Abundance and distribution of habitat classes within 70 201 km² analysis plots.

7

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Agriculture Deciduous

Forest

Developed Open

Space

Evergreen Forest High Intensity

Developed

Low Intensity

Developed

Medium Intensity

Developed

Mixed Forest Scrub/Shrub

Habitat Class

He

cta

res

Figure 4. Mean amounts and standard deviation of habitat classes within 20106 ha (201 km²) analysis plots.

Table 1. Description of classes used to characterize the breeding habitat of Coastal Forest Merlin.

Habitat Type Code Description

Developed

High Intensity HID

Industrial, commercial, and high density residential areas with 80-100% impervious surfaces.

These are zones cleared of major vegetation and include land cover such as concrete, tarmac, or

buildings.

Developed

Medium

Intensity

URES

Medium density residential, commercial and small city parks with 50-79% impervious surfaces.

Generally consist of areas of mixed deciduous/conifer forest, as well as non-native species.

Canopies have a low average percentage of vertical cover. Many non-native species are mixed

with natives trees to make a mixed, low density forest that usually have a minimum of 30%

conifer composition. Patches of vegetation are frequent but highly fragmented. The edge

interface between patches is generally complex in shape.

Developed

Low Intensity RRES

Rural areas with varying amounts of low density residential or commercial activity with 20-49%

impervious surfaces Contains groundcover that consists of a mix of shrub, herbaceous, and

forested areas of mixed species and seral development of conifers and hardwoods. These areas

have similar characteristics as developed medium density, but generally have smaller patch size

Developed

Open Space OPEN

Developed rural and urban areas that include; agriculture, pasture, grasslands, and utility

corridors. Generally have low height vegetation, and square edge configuration

Agriculture AGRI Areas of agricultural, pasture, and human created grassy area. Vegetation ≤ 2 m

Young Forest YOUNG

Early seral stage successional forests with an open or patchy canopy structure. Trees >5m tall,

>20% cover, >75% tree species shed foliage Usually riparian or disturbed areas with Red Alder,

Black Cottonwood, Big Leaf Maple, Vine Maple, conifer saplings and various shrubs.

Mixed Forest INTER

Areas of mixed forest in mid seral development with a patchy canopy closure; Trees >5m tall, >20% cover.

Contains a variety of species consisting of Douglas Fir, Western hemlock, Western red cedar, with some

Hardwoods as well. Arboretums, larger parks, some golf courses, and wooded reserves within areas of more

intense human activity.

Conifer Forest OGM

Mid and late stage seral conifer forest with a heterogeneous spatial configuration. Trees >5m

tall, >20% cover, >75% species maintain leaves. Typical species include Douglas Fir, Western

Hemlock, Western red cedar, grand fir, and Sitka spruce. These forests show a diversity of tree

ages and species, indicating a natural succession. Saplings to snags, young trees to trees

decaying from old age are represented. Patch size and core area tends to be relatively large.

Shrub/Scrub SCRUB

Non forested areas consisting of bare ground, small shrubs, saplings, or herbaceous groundcover

Shrubs/trees <5m tall, >20% cover. These areas consist of recent clear cuts, construction sites, or

areas of disturbance.

8

National Land Cover Database 2006 (NLCD200)

Coastal Forest Merlin Distribution and Density In Different Habitat Classes

The distribution and abundance of a Coastal Forest Merlin population was surveyed from

1986 to 2013. For the purposes of this project, a sample of 219 individual Coastal Forest Merlin

nest sites was used for analysis (Figure 3). Merlin nest sites were located in 4 of the 9 defined

habitat classes; conifer forest, mixed forest, developed medium intensity and developed low

intensity. The highest number of nest sites were located in the conifer forest class; 82, followed

by developed medium intensity 77, mixed forest; 37, and developed low intensity; 23.

The observed nest site densities were significantly higher in the developed medium

intensity and developed low intensity classes than Conifer and Mixed forest. Demographic

surveys revealed that the highest density of Merlin nest sites was located in the developed

medium intensity class which contained 77 of 219 nests or 35.16 % despite the class only

representing 577.08 km² or 4.10% of the available habitat in their home ranges. Similar

associations were noted in the developed low intensity class which contained 23 of 219 nest or

16.89% of 864.21km² or 6.14% of the available habitat.

Habitat Associations

Coastal Forest Merlin Preference

for habitat groundcover composition and

configuration as well as other geographic

and environmental factors was evaluated

by comparing the habitat characteristics

of used home range plots with randomly

generated home range plots. Refer to

appendix B for complete habitat variable

descriptions. In terms of topographic and

hydrographic features Coastal Forest

Merlins utilized locations that were

located in areas with a closer proximity

to areas with greater stream density

(TSD, t = 6.07, df = 105, P < 0.05),

closer to riparian areas (RIPA, Z = -5.59,

df = 105, P = 0.0003), and locations that

were lower in elevation (ELEV, t = 2.15,

df = 105, P < 0.05). In terms of landscape

configuration, Merlin sites were found

more frequently than in habitat classes

with a lower level of patch density

( PD, t = 3.22, df =105 , P = < 0.05),

greater edge density ( ED, t = 9.19, df =

105, P < 0.05), and greater complexity of

patch shape ( SHAPE, t = 2.12, df =105,

P < 0.05).

9

Nest site density had a moderately negative level of correlation for the amount of

impervious surfaces near nest sites (P = 0.22, r² = 0.41, ß = -0.64). Nest sites were located in areas

ranging from 0-75 % impervious ground cover. Nest site densities were not strongly correlated

with the percent forest cover (P = 0.67, r² = 0.14, ß = 0.35). 31 nest sites were located in areas with 5-

30% forest cover while areas with area with greater than 55% forest cover had consisted of 27

nest sites. Table 2. Comparisons of landscape characteristics for Coastal Forest Merlin study plots sampled in the study area. Values are means (± SD).

Landscape Habitat

Variable ª Plot Type t-test df =105

Used

( n =70 )

Random

(n = 37)

t P

Stream Dist. 290.04± 487.63 159.32±147.05 1.59 0.05

Riparian Dist. 498.65 ±845.13 954.19 ±1116.43 2.37 0.05

Stream Density 255.89 ± 306.01 238.42 ± 270.54 6.07 0.05

Elevation 194.86 ± 157.40 312.86 ±388.09 2.15 0.05

Edge Density 37.94 ±12.54 14.16 ±13.08 9.19 0.05

Patch Density 2.92±3.08 4.66±1.57 3.22 0.05

Patch Shape Complexity 1.77 ± .164 1.11 ± .298 2.12 0.05

Patch Shape SD 0.94 ± 0.20 0.72 ± 0 .26 4.87 0.05

Aggregation Index 71.23 ± 14.96 76.83 ± 10.26 2.12 0.05

Patch Size SD 60.35 ± 91.17 52.88 ± 102.53 1.78 0.05

Mean Patch Size 4.30 ± 6.04 1.28 ± .63 3.03 0.05

ª For descriptions see appendix A

Table 3. Outputs for Pearson Correlation coefficient calculations for Coastal Forest Merlin breeding habitat variables.

Landscape Habitat Variable

P r² ß

Level of

Correlation

Riparian Dist. 0.15 0.66 0.81

Negative Strong

Stream Density 0.04

0.75 0.86

Positive Strong

Edge Density 0.23

0.41 0.64

Positive Moderate

Patch Density 0.03

0.42 0.65

Positive Moderate

Patch Shape Complexity 0.17

0.53 0.73

Positive Moderate

Total Forest Cover 0.67

0.14 0.35

Positive Weak

Impervious Surfaces 0.22

0.41 0.64

Negative Moderate

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CONCLUSIONS AND DISCUSSION

Land Cover Characteristics

The project used GIS to analyze important breeding habitat variables and associations for

a population of Coastal Forest Merlin in an 116,660 km² study area spread over Northwest

Washington State and British Columbia, Canada. The analysis did not attempting to predict

occurrence or distribution of Merlins in the study area. The goal was to depict similarities of

breeding habitat variables on a landscape level based on observed sightings of the species. By

using GIS to interface data layers that delineate land cover, land use, anthropogenic influence,

topography, and hydrography it was possible to characterize the study area in terms of the overall

value of each relevant habitat variable as well as their spatial distribution on the landscape. This

analysis method characterizes the habitat in the study area in terms of overall abundance of

habitat classes as well as the relative distributions on the landscape. Analysis determined that

quantifying land cover characteristics and configuration was an effective indicator of the

distribution and abundance of high quality Merlin habitat.

By reconciling the results of the analysis with field collected ground truth data, this

method demonstrated the ability to identify habitat characteristics for Pacific Forest Merlins at a

fine spatial scale over a large geographical area. This technique for habitat characterization can

be accomplished using readily available geospatial data combined with proper selection and use

of key species dependent habitat variables and an assessment of accuracy using reliable

validation data. The product of analysis can be used to delineate areas of high quality habitat for

a focal species, determine the amount of high quality habitat within a study area, and in and

evaluate different management plans designed to protect areas of valuable habitat.

The methods employed in this project could be used to perform analysis of landscape

associations for most species using a relevant set of key habitat variables. The methods could be

used to monitor changes in wildlife habitat before and after disturbances, or at different spatial

and temporal extents or resolution. Wildlife habitat analysis using GIS had the ability to expand

the awareness of habitat abundance, quality, and spatial configuration that would help guide the

resource management decision making process.

Habitat Associations

The spatial configuration of habitat variables and their association with a species

distribution and abundance is a becoming a commonly used method in landscape ecology

(Flather & Sauer, 1996). The analysis conducted for this project exemplified the association of

several key habitat variables on Coastal Forest Merlin and breeding success. Merlin frequently

use concealed perches located at forest edges to surprise and capture their prey, they may also

use their speed and agility to fly below the canopy in and flush prey. Some may use topographic

elements or landscape features to conceal their approach from potential prey (Johnsgard, 1990).

Merlins cache surplus food on a branch or in an unused nest located on a nearby tree (Cade,

1980). These aspects indicate two primary elements of quality foraging habitat are a fragmented

forest configuration with complex edge shape.

11

Breeding sites for Merlins were widespread across the study area and took place in a

variety of natural, semi natural, and development habitats. Merlins avoided using habitat near

areas with high levels of impervious surfaces and large expanses of open areas with abrupt

habitat edges. These relationships was negative with high intensity developed high intensity,

agricultural, and shrub/scrub habitat classes. These classes contained no nest sites and made up

little of the overall land cover in home ranges. Land cover analysis indicated highest Merlin nest

densities were linked lower levels of patch density indicating a preference for a fragmented

landscape common to areas of human development. Merlin home ranges consisted of a greater

variety of different habitat classes which demonstrates a preference for areas with a greater level

of habitat richness. Merlins density was linked with areas with complex patch shape with greater

amounts of habitat edge as indicated by a high level edge density. The association of higher

Merlin nest site densities with areas exhibiting these characteristics in greater amounts than was

what was generally available across the landscape indicates Merlins are demonstrating a

preference for these traits when selecting breeding territory.

Management Implications

The loss or alteration of habitat is an area of concern for the long term success of Coastal

Forest Merlin populations (Drummond & Stillman, 2014). Land cover in the study area

particularly in the study area had been increasing impacted by anthropogenic influences.

Although presently the natural and developed landscape of the study area provides Merlins with

an adequate amount of desirable breeding habitat, the increase of human population and the

resulting development has the potential to degrade or eliminate what currently exists. Current

methods of managing wildlife habitat are varied and diverse due to the different needs required

for multiple species (Rodiek & Bolen, 1991). Effective techniques for wildlife conservation are

seldom used; planning for wildlife habitat conservation is primarily conservative in approach,

and disjointed in application (McKinnon, 1987). As a result of the numerous plans exists that

were developed and managed by different agencies and have various levels of efficacy.

Numerous Federal, state, provincial, and local laws, ordinances, and special provisions exist that

may be used to conserve wildlife and their habitat. Many areas of habitat preferred by Merlins

for nest sites are slated for protection under a variety of regulatory acts (Rullman & Marzluff,

2014). Due to the fragmented approach to conservation, a regional approach to habitat

management may be the best method to help protect existing Merlin habitat. Many areas of high

quality habitat are located on private land not protected by existing management plans.

Incorporating outreach and education for private landowner into management plans may be an

effective method to protect these otherwise vulnerable areas.

ACKNOWLEGEMENTS

I express my sincere gratitude to David Drummond and Roger Stillman of the Merlin

Falcon Foundation who was enthusiastic, supportive, and informative as well as providing a high

level of support and useful feedback that was extremely beneficial to the quality of this project. I

would like to also thank my advisor Dr. Andrew J. Bach for his support and critiques during the

planning and revision stages of the process. And most importantly, I would like to thank my wife

and family for their feedback, patience and support.

12

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APPENDIX A. Variable codes and explanations for landscape metrics used for analyses.

Variable Name Units Description Data Source

ED Edge Density m/ha Amount of edge relative to habitat

class area

NLDC, ESOD

2006 25m

SHAPE Patch Shape Complexity 0.0-

1.0

Greater complexity = ≥1

Less complexity= 1

NLDC, ESOD

2006 25m

PD Patch Density; Habitat

richness

#/ ha Number of different habitat patches

per ha

NLDC, ESOD

2006 25m

TCAI Total Core Area Index 0.0-

100.0

Percent of landscape containing core

area

NLDC, ESOD

2006 25m

SIZE Patch Size ha The mean area of patch size per

class

NLDC, ESOD

2006 25m

WATER Water 0.0-

100.0

Percent of open water in the

landscape

NHD/ NHN 2012

ELEV Elevation m Elevation of plot center USGS DEM 2010

25m

RIPA Distance to Riparian Zone m Distance to the boundary of nearest

riparian area

NHD/ NHN 2012

STRM Distance to Stream m Distance to nearest stream centerline NHD/ NHN 2012

TSD Total Stream Density m/ ha Total length of all streams in each

study plot in the study area

NHD/ NHN 2012

PIS Impervious Surface 0.0-

100.0

Percent of impervious surface in the

landscape

CCAP, ESOD

2006 25m

PFC Forest Cover 0.0-

100.0

Percent of forest cover in the

landscape

CCAP, ESOD

2006 25m

HID Developed High Intensity 0.0-

100.0

Percent of high intensity developed

area in the landscape

NLDC, ESOD

2006 25m

URES Developed Medium Intensity 0.0-

100.0

Percent of medium intensity

developed area in the landscape

NLDC, ESOD

2006 25m

RRES Developed Light Intensity 0.0-

100.0

Percent of light intensity developed

area in the landscape

NLDC, ESOD

2006 25m

MIXED Deciduous/Mixed Forest 0.0-

100.0

Percent -mixed forest in the

landscape

NLDC, ESOD

2006 25m

OGM Evergreen Forest 0.0-

100.0

Percent of conifer forest in the

landscape

NLDC, ESOD

2006 25m

SHRUB Shrub/ Scrub 0.0-

100.0

Percent of shrub/ scrub land in the

landscape

NLDC, ESOD

2006 25m

YOUNG Young Mixed Forest 0.0-

100.0

Percent of young mixed in the

landscape

CCAP, ESOD

2006 25m

AG Agriculture 0.0-

100.0

Percent of agriculture (pasture/hay)

in the landscape

CCAP, ESOD

2006 25m