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Title
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An Assessment of the Raptor Strike Avoidance Program at Seattle-Tacoma International Airport
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Date
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2016
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Creator
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Trageser, Hannah Leigh
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Subject
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Environmental Studies
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extracted text
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AN ASSESSMENT OF THE
RAPTOR STRIKE AVOIDANCE PROGRAM
AT SEATTLE-TACOMA INTERNATIONAL AIRPORT
by
Hannah Leigh Trageser
A Thesis
Submitted in partial fulfillment
of the requirements for the degree
Master of Environmental Studies
The Evergreen State College
June 2016
©2016 by Hannah Leigh Trageser. All rights reserved.
This Thesis for the Master of Environmental Studies Degree
by
Hannah Leigh Trageser
has been approved for
The Evergreen State College
by
________________________
Mike Ruth, M.Sc.
Member of the Faculty
________________________
Date
ABSTRACT
An Assessment of the Raptor Strike Avoidance Program at Seattle-Tacoma International
Airport
Hannah Leigh Trageser
Wildlife and airplanes do not mix at airports nationwide. Wildlife management at
airports is crucial for maintaining pilot and passenger safety. Red-Tailed Hawks (RTHA)
are one of the most numerous and problematic avian species at Seattle-Tacoma
International Airport (Sea-Tac). Managing RTHA through the Raptor Strike Avoidance
Program (RSAP) helps ensure aviation safety at Sea-Tac Airport. The goal of the RSAP
is to capture hawks at Sea-Tac and translocate raptors 75 miles north to an agricultural
area with relatively more prey. The RSAP partners with the Falcon Research Group
(FRG) non-profit organization. Researchers at FRG give each individual RTHA trapped
at Sea-Tac a blue or yellow patagial wing tag. Morphometric data is collected for each
hawk. Blue-tagged adult hawks are migrating adult and/or subadult RTHAs that were
translocated to Bow. Yellow-tagged hawks are adult hawks that are nesting Sea-Tac
residents and in many cases they were also translocated to Bow. Citizen scientists collect
RTHA resights with blue or yellow tags and hawk locations are given directly to airport
staff. The RSAP’s RTHA resight data will be used to address the research question: Has
the Raptor Strike Avoidance Program at Seattle-Tacoma International Airport succeeded
in keeping raptors away from airports and airplanes in 5 airports in western
Washington? The success of the raptor program is assessed using resight data to calculate
raptor return rates to Sea-Tac. Geographic Information Systems (GIS) spatial analysis is
used to determine if raptors are present within five-miles of Sea-Tac, King County
International Airport/Boeing Field, Snohomish County/Paine Field, Renton Municipal,
and Bellingham International Airports. Analysis indicates Sea-Tac’s translocated
RTHAs indicate a 14.55% return rate, which indicates high program success at Sea-Tac
Airport. Additionally, translocated blue-tagged hawks prefer low elevations (x̄ =47.71
meters) and show no habitat preferences.
Table of Contents
Chapter 1: Literature Review ..................................................................................... 1-13
Wildlife Risks to Aviation .......................................................................................... 1-3
Birds in Built Environments ..................................................................................... 3-5
Habitat Management and Land Use Planning at Airports .................................... 5-7
Airport Ecology Research ......................................................................................... 7-8
Wildlife Deterrents at Airports ................................................................................. 8-9
Wildlife Trapping and Relocation .......................................................................... 9-11
Issues of Wildlife Translocation .......................................................................... 9-11
Raptor Return Rates .............................................................................................. 11-13
Chapter 2: Introduction to Master’s Thesis Research ........................................... 13-19
Thesis Research Question ........................................................................................... 13
Study Introduction Site Identification: Sea-Tac Airport ................................... 13-14
The Raptor Strike Avoidance Program .................................................................... 14
Study Species .......................................................................................................... 14-15
Citizen Science ........................................................................................................ 15-16
Data Quality ............................................................................................................ 17-18
Chapter 2 Figures ........................................................................................................ 19
Chapter 3: Analysis of the Raptor Strike Avoidance Program ............................. 20-47
Materials & Methods ............................................................................................. 21-24
Study Area: Western Washington Airports..................................................... 21-22
Raptor Data Collection ........................................................................................... 22
GIS Data Management for Airport Operations .............................................. 22-23
GIS Data Management for Red-Tailed Hawk Resights ....................................... 23
GIS Spatial Data Analysis of Red-Tailed Hawk Resights .............................. 23-24
Statistical Analysis ...................................................................................................... 24
Results ..................................................................................................................... 24-26
Pivot Table Analysis ................................................................................................ 24
Repeat Red-Tailed Hawks ................................................................................. 24-25
Habitat Preferences Among Blue-Tagged Red-Tailed Hawks ............................ 25
Elevation Preferences Among Blue Tagged Red-Tailed Hawks ......................... 25
Birds in Airport Buffers ..................................................................................... 25-26
Program Success Evaluation .................................................................................. 26
Discussion ................................................................................................................ 26-28
Chapter 3 Figures ................................................................................................... 29-46
Chapter 3 Tables ......................................................................................................... 47
Chapter 4: Conclusions and Recommendations for Future Research.................. 48-49
Conclusions .................................................................................................................. 48
iv
Recommendations for Future Research ............................................................... 48-49
References ................................................................................................................... 50-54
Appendix ..................................................................................................................... 55-57
Variables ...................................................................................................................... 55
Detailed GIS Methods ............................................................................................ 55-57
GIS Data Management....................................................................................... 55-56
GIS Spatial Analysis ........................................................................................... 56-57
v
List of Figures
Figure 1. Swedish Goshawk Traps Used For Raptor Trapping at Seattle-Tacoma
International Airport
Figure 2. GIS Data Management Workflow For Red-Tailed Hawk Resight Data
Figure 3. Weekly Avian Survey Locations at Seattle-Tacoma International Airport
Figure 4. Tyee Valley Golf Course Avian Survey Locations at Seattle-Tacoma
International Airport
Figure 5. Blue-Tagged Red-Tailed Hawk Resights From the Raptor Strike
Avoidance Program
Figure 6. Red-Tailed Hawk Elevation Preferences (USGS Terrain_Slope layer)
Figure 7. JMP Output Elevation Preferences Among Blue-Tagged Red-Tailed
Hawks
Figure 8. Blue Tagged Red-Tailed Hawk Resights, Five Mile Airport Buffers, and
Five Mile Translocation Site Buffer
Figure 9. Blue-Tagged Red-Tailed Hawk Resights Within Translocation Site FiveMile Buffer (n= 18)
Figure 10. Blue-Tagged Red-Tailed Hawk Resights Within Bellingham
International Airport Five-Mile Buffer (n=6)
Figure 11. Blue Tagged Red-Tailed Hawk Resights Within Snohomish County/Paine
Field Airport Five-Mile Buffer (n=0)
Figure 12. Blue-Tagged Red-Tailed Hawk Resights Within Seattle-Tacoma
International Airport, King County International Airport/Boeing Field, and Renton
Municipal Airport Five-Mile Buffers (Sea-Tac n=6, Renton n=5, Boeing n=7)
Figure 13. Distances of Red-Tailed Hawk Resights to Bellingham International
Airport
Figure 14. Distances of Red-Tailed Hawks Resights from Sea-Tac, Boeing Field, and
Renton Municipal Airports
Figure 15. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles
of Sea-Tac Airport’s Center (n=6)
Figure 16. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles
of Sea-Tac Airport’s Center (n=5)
vi
Figure 17. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles
of King County International Airport’s Center (n=7)
Figure 18. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles
of Bellingham International Airport’s Center (n=6)
Figure 19. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles
of Paine Field Airport’s Center (n=0)
Figure 20. Distances of Red-Tailed Hawk Resights From Translocation Site in Bow,
Washington (n=18)
Figure 21. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles
of the Translocation Site’s Center (n=18)
Figure 22. Blue Tagged Red-Tailed Hawk Resight Density
Figure 23. Red-Tailed Hawk Strikes With Aircraft at Seattle-Tacoma International
Airport From 1995-2015 (FAA Wildlife Strike Database)
Figure 24. Red-Tailed Hawk Strikes With Aircraft at King County International
Airport/Boeing Field From 2006, 2010 and 2011 (FAA Wildlife Strike Database)
Figure 25. Mean Number of Blue Tagged Red-Tailed Hawk Resights By Habitat
Type
Figure 26. Repeatedly Sighted Translocated Blue-Tagged Red-Tailed Hawks in the
Dataset
Figure 27. BL50’s Flight Path Story Over Time
Figure 28. BL10’s Flight Path Story Over Time
Figure 29. BL82’s Flight Path Story Over Time
Figure 30. BL15’s Flight Path Story Over Time
Figure 31. BR57’s Flight Path Story Over Time
Figure 32. BR9’s Flight Path Story Over Time
Figure 33. BL31’s Flight Path Story Over Time
Figure 33. BL7’s Flight Path Story Over Time
vii
List of Tables
Table 1. Washington State Department of Transportation Airport Names and
Operations
Table 2. Results Summary
viii
Acknowledgements
This work is the final product of a giant support network and collaboration among
various individuals. I am truly grateful for the help and encouragement that I have
received while writing my Master’s thesis. I thank the Port of Seattle’s Aviation
Operations Wildlife Hazard Mitigation & Conservation Office for allowing the use of the
raptor resight data collected as part of their Raptor Strike Avoidance Program that proved
so instrumental in reaching the conclusions presented in this thesis. In particular, a
special thank you to Steve Osmek, the Port of Seattle Wildlife Biologist Manager, who
took me on as an intern in November 2013, and tasked me with summarizing avian strike
data using Microsoft Excel pivot tables, and learning about airport wildlife hazard
management. I am grateful for Steve’s encouragement, which inspired me to present a
honeybee report on behalf of the Port of Seattle at the 2015 North American Bird Strike
Conference in Montreal, Quebec, Canada. This was a unique opportunity for
professional development. In addition, I owe a great deal of thanks to Mikki Viehoever,
the Port of Seattle Wildlife Biologist, Patrick Viehoever, USDA Wildlife Services
contractor for the Port of Seattle, and Bud Anderson Falcon Research Group contractor
for the Port of Seattle who assisted with the data collection and constantly supporting me
with feedback along the way. Without this raptor dataset and collaborations made in the
birding community, this thesis would not have been possible. I also thank Carole Hallett,
Pacific Habitat Services contractor for the Port of Portland for her generosity in providing
me with raptor handling training and brainstorming possible thesis questions. I thank
Carter Timmerman, Washington State Department of Transportation GIS Analyst who
helped me navigate airport operations in Washington State and to refine the scope of my
research. Additionally, thanks to Laurence Schafer, USDA Wildlife Services Wildlife
Biologist who helped me think critically about the limitations of my research and how to
make my research credible and defensible for scientific peer-review. The faculty and
especially the Master of Environmental Studies program at The Evergreen State College
also played a fundamental role in my success. First and foremost, thank you to Dina
Roberts, my first thesis reader for her endless guidance, feedback and support with every
step of this project. I also thank my second thesis reader, Mike Ruth for GIS support and
his enthusiasm and limitless knowledge of GIS, both traits that I hope to have retained.
Lastly, I thank Rich Poelker for reviewing my thesis drafts and providing wonderful
feedback.
ix
Chapter 1: Literature Review
This Literature Review will first discuss wildlife risks to aviation to address the
importance of minimizing bird strike collisions with aircraft at airports. Birds in built
environments will be explored next, and habitat management and land use planning at
airports will follow. Current airport ecology research will be explored as well as wildlife
deterrents at airports. Wildlife trapping and relocation will be discussed next and then
issues of wildlife relocation will follow. The introduction of the thesis and methods of
the research will come next. The results and conclusions will be examined with a
discussion of how these findings may be used to inform airport wildlife biologists about
improvements made to aviation safety through raptor relocation and conservation
biology.
Wildlife Risks to Aviation
US Airways Flight 1549 collided with a flock of migratory Canada geese in 2009,
causing an emergency landing on the Hudson River between New York City and New
Jersey (Henkes 2009). The geese were ingested into both engines of Flight 1549 and
caused significant internal damage to engine machinery, resulting in engine failure and
loss of control of the aircraft. The collision over the Hudson River led to further
improvements in reducing avian attractants (palatable foods for wildlife such as seeds,
nuts, and berries) using a wildlife management approach at some airports in the United
States. Larger bird species are of most concern to the aviation industry. Aircraft often
strike birds on the runway and in the airfield. Such strikes have caused deaths among
passengers and pilots in the past, and have caused significant damage to aircraft. Coccon
1
et al. (2015) predicts that due to the projected increased air traffic in the United States,
resulting from increased population demand for air travel, there will be a significant
increase in wildlife strike hazard risks and high frequency of strike events at airports in
the United States. Therefore, managing wildlife risks at airports is important for flight
safety.
The Federal Aviation Administration (FAA) is the federal branch of the United
States Department of Transportation responsible for maintaining aviation safety in the
United States. The FAA aims to maximize safety for air travelers and minimize future
risks of potential wildlife-aircraft strike events. In order for aviation safety standards to
be met, habitats near the runway need to be unpalatable to minimize bird-airplane
collisions. Eliminating shrubs and potential wildlife habitat near the airfield decreases
strike events. Red-Tailed Hawks (Buteo jamaicensis) (RTHA) are a nuisance to aviation
safety at Sea-Tac. Eliminating suitable RTHA habitat attractants would minimize strike
events of aircraft with hawks at Sea-Tac and would simultaneously save the aviation
industry bird strike damage costs to aircraft at Sea-Tac.
Dolbeer et al. (2000) identified RTHAs as a hazardous species to aviation in the
FAA Wildlife Strike Database (database) documented from 1991-1998. The group
ranked first as the most hazardous species to aviation were deer, vultures came second,
and geese were the third most hazardous wildlife group to aviation. Out of a total of 21
listed species in the database, the hawks (buteos) species group ranked fourth. The
buteos species group reported 452 strikes, 67 reports noted effect on flight, 22 reports
estimated damage costs, 95 reports noted damage, and the estimated damage costs for
hawks to the aviation industry were $389,000 (Dolbeer et al. 2000). In the database for
2
Sea-Tac, 58% of species struck by aircraft are unknown, 8% barn owls, 7% European
starlings, 6% gulls, 6% killdeer, 6% barn swallows, 6% American kestrels, and 4% were
RTHAs. Additionally, this database showed RTHAs caused substantial damage to civil
aircraft at Sea-Tac in September 2014 and March 2015. Managing RTHA populations at
Sea-Tac in the fall and spring months is crucial to enable aviation safety and
simultaneously save the aviation industry from future bird strike damage costs.
Birds in Built Environments
RTHAs not only exist in airport habitats, but RTHAs also inhabit urban
environments. In urban areas, RTHA population distribution depends on prey
availability, nesting sites, and perch foraging locations (Belant et al. 2013). Hawks
generally seek out habitat with lots of food such as squirrels and voles both indicative of
high quality habitat (Janes 1984 and Witmer 2011). A study conducted by Stout et al.
(2009) found that RTHAs in urban-suburban southeast Milwaukee, Wisconsin adapted
and thrived within high-density built environments.
Reproductive success is measured and driven by the amount of fledged progeny
produced per year (Janes 1984) and serves as an indicator index for high habitat quality
(Stout et al. 2006). Research shows that hawks have learned to adapt to urban
environments and exhibit reproductive and foraging success in habitats with abundant
prey-based food resources. In urban environments, RTHAs often nest on man-made
structures (Stout et al. 2009). RTHAs display similar habitat preferences at Sea-Tac
similar to research findings in Milwaukee. Environments with abundant habitat features
such as perches serve as optimal foraging grounds for RTHAs and more perches indicate
higher reproductive success among RTHA populations (Stout et al. 2009, Janes
3
1984). These hawks near roads demonstrated high reproductive success in urban
areas. Research by Stout et al. (2009) found that perches in close proximity to freeways,
highways, and local roads provide optimal hunting habitats for hawks. Roadside hunting
is also dangerous for RTHAs, due to fatalities of hawks with semi-trucks or cars. When
RTHAs hunt in the median and try to fly up some cannot gain altitude fast enough and
sometimes get struck by vehicles. Grassy habitat margins between roads and carcasses
along vehicular transportation systems provide opportunistic foraging for hawks. Similar
to grassy road margins along vehicle transportation corridors, airports also have grassy
margins between runways, which oftentimes supports hunting habitat for RTHAs. Many
airports provide similar habitat for wildlife.
Habituation among birds in a built environment means that there is reduced (or
no) behavioral response when a bird is exposed to a repeated stimulus. Some airports use
various harassments to nuisance birds such as shotguns and pyrotechnic launcher
harassment devices in addition are exposed to loud airplanes taking off and
landing. Oftentimes these birds become accustomed to the harassment stimuli used by
trained wildlife staff and birds carry on with their lives near the source of the stimuli.
These species inhabit urban areas and have become habituated. Habituation is a dynamic
process and illustrates how bald eagles (Haliaeetus leucocephalus) in the Accipitridae
family have thrived in urban habitats and learned how to coexist with humans in built
environments. Research by Guinn (2013) found that eagles have become desensitized
and no longer threatened by stimuli induced from human exposure over time. Ospreys
(Pandion haliaetus), like eagles belong to the same Accipitiformes taxonomic order, but
are in two different families. Ospreys often breed and nest on man-made structures (such
4
as telephone poles). Resident breeding pairs of RTHAs oftentimes return to the same
nest site year after year and breed at Sea-Tac. Research conducted by Stout et al. (2009)
found that RTHAs breeding in urban areas of Milwaukee, Wisconsin have shown to have
high nest productivity and successful progeny. Like bald eagles, RTHAs belong to the
Accipitridae family and have the potential to share similar habituation
characteristics. Habituation of repeated stimuli among the Accipitridae family has
implications for airport wildlife biologists because RTHAs have become comfortable
nesters and thrived in urban airport environments despite all the noise and repeated
stimuli at Sea-Tac.
Habitat Management and Land Use Planning at Airports
Airport wildlife biologists must prioritize airport management efforts towards
maintaining airport habitat that decreases RTHA attractiveness and abundance through
landscape planning. Implementing habitat modification land use practices at airports is
an effective way to decrease wildlife hazards around the airfield. Land use strategies
consider various subdisciplines of biology, including wildlife management, landscape
ecology, conservation biology, geography, and sensory ecology (Blackwell 2009).
Landscape manipulation at civil airports helps guide landscapers, wildlife biologists,
stormwater managers, airport operations, and other airport personnel to collaboratively
decide on a particular land use plan at an airport.
Habitat modification is an effective tactic to deter birds from civil airports to
promote the bird strike avoidance program. Habitat modification first eliminates shrubs
and other enticing habitats. Landscapers responsible for habitat modification projects
also sow taste aversion plantings such as fall fescue (Festuca arundinacea) grass.
5
Human landscaping techniques to reduce attractants at airports is essential and shortplanted grass, low nutrition topsoil to prevent tall grass growth, and fungicidal taste
repellant aversions are also planted (Blackwell 2009).
An integrative approach is essential for effective landscape and wildlife
management at airports. Martin et al. (2011) found that eliminating wildlife attractants
and reducing airfield use by wildlife through an integrated approach using habitat
modification paired with wildlife control tactics mitigates wildlife strike risk at
airports. Barras and Seamans (2002) emphasize that an integrative wildlife management
approach is one that decreases water resources, food availability, perching sites, loafing
grounds, and woody vegetation, but simultaneously deters hazardous wildlife through
repeated harassment methods. Additionally, tall trees, woody vegetation, and shrubs
provide perching habitats for birds. Reducing tall and shrubby vegetation habitats is
crucial for eliminating various avian species at airports that are reliant upon these habitat
types for perching, nesting and feeding. For successful vegetation management, it is
recommended that civil airports plant tall fescue grass as the primary vegetation ground
cover between taxiways and runways at airports. Tall fescue is the chosen vegetation
planted at airports (including Sea-Tac) because this grass seed mix incorporates a tasterepellent fungus (Neotyphodium coenophialum) to deter grazing avian species at the
airport (Port of Seattle’s Wildlife Hazard Management Plan 2004). The Port of Seattle’s
Wildlife Hazard Management Plan requires the restoration crew at Sea-Tac to maintain a
three-inch maximum fescue grass height by mowing and mowing detracts wildlife at the
airport. Similarly, research conducted by Barras and Seamans (2002) illustrate the
importance of maintaining short fescue grass height year around, so mowing regimens
6
are used on a regular basis to maintain fescue grass height between 15-25 centimeters.
This length is similar to the length required by the Port of Seattle’s Wildlife Hazard
Management Plan.
Airport Ecology Research
The ecology of an airport is quite complex and dependent upon a trophic cascade
of vegetation, insects, mammals, and raptor populations. A trophic cascade describes
predator and prey relationships within a food web. Airports have their own ecology
because they have wide-open grassy fields in between taxiways and runways. Airports
also have built structures that may unintentionally provide habitat for
wildlife. Ecological habitat has the potential to attract RTHAs. Studies that pertain to
airport ecology are discussed further in this section.
Research conducted by Barras and Seamans (2002) illustrated a strong
relationship between the food web dynamics of airport fescue groundcover vegetation,
invertebrates, small mammals, and hazardous bird populations within an airport
environment. For example, changing one organism can drastically change the abundance
of another animal residing in an airport habitat.
Barras and Seamans (2002) found that longer airport vegetation encourages more
invertebrates. A rise in invertebrates facilitates an abundance of small mammals due to
an increased prey resource for the mammals. Small rodents such as shrews feed
predominantly on invertebrates. More insects attract more small birds. Both the small
mammals and small birds attract RTHAs. Attracting hazardous birds such as raptors is
problematic for aviation safety at airports nationwide. At Kansas City Airport, Witmer
(2011) found that tall fescue grass height attracts rodents. Witmer (2011) demonstrated
7
that airport environments with tall and medium fescue grass heights have higher rodent
carrying capacities. Airport habitat with short fescue grass supports lower rodent
populations and reduced hawk populations. Reducing hawk attraction to airports
involves consistent vegetation modification (Witmer 2011). At Chicago O’Hare
International Airport, Guerrant et al. (2013) illustrated how mowing regimens have been
used as a form of habitat modification to minimize suitable long grass habitat for rodents
that attract raptors. Vegetation management and wildlife deterrents at airports go hand in
hand as common management protocols implemented simultaneously to reduce wildlife
at airports.
Wildlife Deterrents at Airports
Reducing these avian species through non-lethal approaches is integral to SeaTac’s wildlife program. Exclusion devices are physical barriers (or fences) built along
the perimeter of the airport to block wildlife from entering the runway. Exclusion fences
are built tall and oftentimes at an angle underground to prevent wildlife such as coyotes
from digging their way into airport property and colliding with aircraft.
Another example of an exclusion device used at civil airports is a stormwater
detention pond with netting. A detention pond at an airport collects tarmac and aircraft
chemical stormwater runoff and is usually netted to exclude waterfowl species.
Another form of wildlife damage control is harassment of birds at
airports. Harassing avifauna is a deterrent used at airports to scare birds away from the
runway. Harassment uses loud pyrotechnic launchers as a method to impede frequent
visiting nuisance birds to improve air safety for pilots and passengers (DeVault 2013).
8
Loud noises generated from pyrotechnics elicit the stress and fear-induced
physiological response pathway in birds. This ignited sense of fear from the loud noise
harassment device in the urban environment has the potential to get passed down to
future avian generations and has been an exemplary tool to minimize hawks and other
birds on airport property. While it is not fully understood, aircraft avoidance through
human harassment methods using pyrotechnics and shotguns may be a learned behavior.
When avian species become acclimated to harassment, a shotgun may be used for
lethal removal as a last resort when invasive bird species consistently return back to the
airport in flocks. Although lethal removal has been shown to be effective for decreasing
wildlife abundance at airports, this method is discouraged by biologists who prefer to
protect raptor populations.
Wildlife Trapping and Relocation
Wildlife biologists have turned to non-lethal methods of management such as
raptor trapping and relocation as a solution to numerous RTHAs at some airports.
Wildlife translocation has various goals and objectives, each different and unique.
Research conducted by Griffith et al. (1989) explains wildlife trap and relocation as a
method to introduce a species to a new environment. Additionally, wildlife translocation
can also eliminate a species from one habitat and change the composition of another.
Issues of Wildlife Translocation
Translocation of wildlife involves using a trap that is species specific and a
federal permit. Wildlife relocation has legal, ecological, and economic efficiency
concerns. The primary legal concern of trapping and translocating wildlife is the
9
necessity for a permit for any migratory bird species under the Migratory Bird Treaty Act
(MBTA) or species listed as threatened or endangered under the Endangered Species Act
(ESA). Under Washington State Department of Fish & Wildlife (WDFW) state law, all
activities related to trapping and relocating birds require a state permit. Stricter
guidelines apply for species listed under federal law under the ESA and/or MBTA. Some
hawks require a permit for trapping and relocating listed birds to a more optimal habitat
to reduce large avian presence in the airfield. Therefore airports oftentimes trap raptors.
Ecological concerns of relocation require understanding the impacts of the
relocated wildlife to other members of the same species and other native species at the
release site. Some of the risks of relocation include competition, predation of native
species, and increased mortality risks of the relocated species.
Invasive species should not be trapped and relocated (Craven et al. 1998). Craven
et al. (1998) describes that invasive avian species such as house finches (Haemorhous
mexicanus), rock doves (Columba livia), house sparrows (Passer domesticus), and
European starlings (Sturnus vulgaris) should not be trapped and relocated. The
introduction of invasive species to a new release site facilitates competition among
relocated invasive species and native species at the release site. Schafer et al. (2002)
discussed that the relocation process can be a stressful experience for relocated wildlife
and has the potential to impact native species.
There are significant financial expenditures to transport raptors from airports to
the relocation site. Curtis et al. (2013) discussed the economic efficiency of raptor trap
and relocation programs at airports. Raptors are often transported across geographic
boundaries such as mountain ranges, 40-200 miles away, and one-two hours from the
10
airport. The raptor transportation process includes leg banding and wing tagging
raptors. Banding and tagging birds are time consuming activities for airport wildlife
staff. Time spent transporting raptors cuts into an airport wildlife biologists’ daily work
routine. Many biologists do not have enough time to transport birds during their work
shift.
Proper practice of animal care is essential for translocated raptors. Curtis et al.
(2013) illustrates wildlife handling training and proper transportation methods to
minimize stress of trapped and relocated RTHAs. Each RTHA should be hooded and
treated with proper care throughout the duration of the trap and relocation
program. RTHA’s feet should be wrapped with elastic vet-wrap for restraint. Kennels
that the raptors are transported in should be filled with bedding material and raptors must
be released promptly after they are caught to minimize hawk stress response pathways.
Raptor trap and relocation programs are used as a means for managing nuisance
wildlife at Sea-Tac, but not at all civil airports. These programs are relatively new
amongst wildlife aviation operations as of the 2000’s. The success of these programs are
understudied since they are not yet numerous and widespread across airports
nationwide. Wernaart et al. (1999) emphasized that a successful raptor program is one
that lessens the likelihood of a RTHA to be hit by an aircraft.
Raptor Return Rates
Raptor return rates are indicators of program success at airports with wildlife
programs. A successful raptor program at an airport has low raptor return rate
percentages defined as low RTHA re-capture rates below 15.9% and low resights at
11
airports (Schafer et al. 2002). This should result in a decrease in RTHA strike events
with aircraft after a raptor program has been fully established (Schafer et al. 2002).
Studies by Wernaart et al. (1999), Schafer et al. (2002), and Anderson and Osmek
(2005) have calculated raptor return rates associated with raptor relocation programs at
airports; little is known about the success of airport raptor programs. Wernaart et al.
(1999) found that the return rate for relocated RTHAs at Toronto Pearson International
Airport was 4%. Schafer et al. (2002) found that the return rate for relocated RTHA at
Chicago O’Hare International Airport (ORD) was 15.9%. Research at ORD also found a
33% return rate for relocated RTHA with attached very high frequency transmitters
(Schafer et al. 2013). Previous research at ORD used very high frequency radio
transmitters and satellite telemetry to track airport RTHAs using Global Positioning
System (GPS) coordinates to assess raptor returns (Schafer et al. 2002). Telemetry
allows airport wildlife biologists to track movement pathways of avifauna at airports
post-release from the relocation site.
Research completed by Anderson and Osmek (2005) found that during the years
of 2001-2005, the return rate for relocated RTHA at Sea-Tac was 0%. Since 2005, SeaTac has collected substantially more RTHA resighting data since this return rate was first
established. The program was not reliable at 0% and the Port of Seattle has remedied this
with more RTHA data collection.
Airport wildlife biologists have not reached agreement upon what return rate
percentages or ranges define a successful program at an airport. Considering Toronto and
O’Hare the return rates for relocated raptors back to airports range from 0%-33%. For
the purposes of this thesis, rates less than 15.9% are successful. Furthermore, due to
12
research and information gaps in the literature, the success of raptor programs at airports
is understudied, as well as raptor elevation preferences, and habitat preferences of
relocated raptors. Thus, raptor return rates, elevation, and habitat preferences are
assessed for the Raptor Strike Avoidance Program at Sea-Tac.
Chapter 2: Introduction to Master’s Thesis Research
Thesis Research Question
I assessed the effectiveness of RTHA capture and relocation as a method for
decreasing avifauna at Sea-Tac. RTHA resight data from the Port of Seattle Aviation
Operations Raptor Strike Avoidance Program at Sea-Tac are to address the research
question: Has the Raptor Strike Avoidance Program at Seattle-Tacoma International
Airport succeeded in keeping raptors away from airports and airplanes at 5 airports in
western Washington? The null hypothesis is that translocated Red-Tailed Hawks are
equally as likely to be at one airport as another of the five airports given we know RedTailed Hawks have ranged from British Columbia to California.
Study Introduction Site Identification: Sea-Tac Airport
The Port of Seattle owns and operates Sea-Tac Airport, located in a highly
urbanized area of south Seattle, two miles east of Puget Sound. Industrial, commercial,
forest, parks, lakes, ponds, and streams are a few habitat types found near Sea-Tac. At
Sea-Tac Aviation Operations wildlife staff harass wildlife away from airport property and
devise strategies to make airport habitat unsuitable for wildlife (especially for avian
species). Aviation Operation’s wildlife biologists at Sea-Tac prioritize their efforts to
13
minimize aircraft collisions with RTHAs and maximize aviation safety through a
comprehensive program devoted to raptor trapping and relocation.
The Raptor Strike Avoidance Program
The Raptor Strike Avoidance Program (RSAP) began in June 2001 at Sea-Tac
Airport (Figure 3). RSAP uses raptor trap and relocation as a non-lethal biological
approach to reduce raptor collisions with aircraft at Sea-Tac. Raptor trapping and
relocation is one form of wildlife management implemented at civil airports in the Pacific
Northwest (including Sea-Tac, Portland International Airport (PDX), Vancouver
International Airport (YVR) and Salt Lake City International Airport (SLC)). Sea-Tac,
PDX, YVR, and SLC civil airports have been working collaboratively on a Western
Airports Raptor Research and Management (WARRM) working group to minimize strike
events with RTHAs and enhance aviation safety at airports.
Study Species
Pilots can lose control of their aircraft if birds collide with aircraft
engines. RTHAs are most abundant at Sea-Tac and in the past, aircraft have struck
RTHAs at Sea-Tac. Aircraft can strike large birds and lose steering capabilities.
RTHAs are numerous at Sea-Tac because they are a habitat generalist species that
thrives in many habitat types (Hull et al. 2008). Sea-Tac provides an abundance of
suitable hunting habitat, which attracts RTHAs to prey upon voles and other small
mammals at this airport. Raptors such as RTHAs are considered a “hazardous” avian
species at Sea-Tac because they have a substantially large biomass and have the potential
to exert a considerable force on airplane engines and other parts of the airplane.
14
Additionally, RTHAs are the most common raptor species trapped and documented at
Sea-Tac. In order to avoid future raptor strikes to aircraft at Sea-Tac, there was
significant pressure for Aviation Operations to begin a relocation program for RTHAs.
The RSAP uses up to five goshawk traps to capture hawks at Sea-Tac and
relocates birds 75 miles north to Bow, Washington (Figure 1). Anderson and Osmek
(2005) determined Bow as a high quality habitat for RTHAs because of its rich prey
abundance and sufficient winter raptor population presence. Thus, Bow is a suitable
habitat for raptors to be relocated to by airport wildlife staff.
Just prior to release, blue and yellow wing tags are attached to the hawks to
indicate that the birds were originally trapped at Sea-Tac and relocated to Bow. A blue
wing tag indicates that the raptor is a migrating adult and/or sub-adult at capture and a
yellow wing tag indicates that the hawk is an airport resident at capture. Other raptor
species translocated at the airport are given a silver United States Geological Survey
(USGS) leg band and this leg band number is sent to the United States Bird Banding
Laboratory. Morphological data as body mass (g), wing chord (mm), tail length (mm),
hallux (mm), exposed culmen (mm), and tarsus (mm) lengths of each relocated RTHA is
documented by a raptor specialist in Bow.
Citizen Science
Citizen science data collection can help reduce airport wildlife staff time and
money within the limited financial budget allocated to the Aviation Operations’ wildlife
management division. When the RSAP was first launched by the Aviation Operations in
2001, citizen scientists actively began raptor data collection for blue and yellow tagged
avifauna in western Washington. Recreational birdwatchers in the community assist with
15
data collection. Support by the public for data collection is highly beneficial to the
success of the RSAP.
Hawk identification classes are taught once in the winter by the Falcon Research
Group contractor based out of Bow, Washington. The Falcon Research Group non-profit
organization, led by Bud Anderson works collaboratively with the RSAP at Sea-Tac
Airport. Classes are held once a year in Seattle, Mount Vernon, and Bellingham.
Participants are notified about the classes through a list-serv. Classes last five weeks and
occur one day a week. The hawk course includes a one-hour lecture supplemented with
slides for participants to practice hawk identification skills and a full day field trip to the
Skagit Valley Flats devoted to field observation experience identifying raptors.
Citizen science has been a long running and efficient method of collecting avian
abundance and distribution data. Data collection involves voluntary participation among
the local birding community and wildlife biologists at Sea-Tac Airport. Participation
among birders in Washington State has been fundamental to RTHA resighting data
collection for the RSAP at Sea-Tac. Citizen science is an efficient means of gathering
numerous avifauna point counts over time and allows more eyes to look out for airport
birds over an extensive territory year-round. Public eyes on airport birds increases raptor
reporting rates and generates an extensive dataset with a large raptor sample
size. Furthermore, due to staffing and funding constraints, data collection conducted by
birdwatchers in the community is integral to the RSAP. Locally collected data by the
community is especially ideal when research funding is scarce.
16
Data Quality
Numerous publications use and cite citizen science data. The National Audubon
Society launched the Christmas Bird Count (CBC), which is the longest running and
continuous citizen science program. For example, both the CBC and eBird are
exemplary models of citizen science because they are widely cited in peer-reviewed
literature and are considered credible avian datasets by the scientific community (Dunn et
al. 2005 and Sullivan et al. 2014). Cited citizen science in scientific literature points to
the legitimacy of using citizens in the community as a means for collecting avian
abundance and distribution data for the RSAP. Research by Dunn et al. (2005)
illustrates how citizen science uses public participation to conduct avian point counts and
enhances data quantity. Similarly to the CBC and eBird, the RSAP uses public
participation in scientific research to gather RTHA location data. This participation
facilitates public engagement and education among the local community. The program
also generates a larger raptor dataset that can be used for further analysis. Like eBird and
CBC, the RSAP has an extensive raptor resighting dataset, which has the potential to
educate and inform the public and airport wildlife staff about raptor threats to aviation if
avifauna resightings are close to airports. Additionally, a large raptor dataset can be
analyzed and interpreted in various ways to determine the effectiveness of the raptor
program at Sea-Tac.
This RTHA dataset is the basis of study for the thesis. Only blue-tagged RTHAs
are used with a total of 144 observations over 14 years (from 2001 to 2015). The yellow
marked birds were not considered in this analysis because they were resident birds so we
knew they would be resighted often near Sea-Tac. It is believed that these resident birds
17
are more airport savvy and therefore they would not get struck as frequently. These birds
are also seen driving other RTHAs away as they are territorial and do perhaps help the
airport from keeping the young and non-airport savvy birds from getting struck at SeaTac. To eliminate sample bias within the dataset, resightings from the Port of Seattle
staff and yellow-tagged RTHAs were omitted. The sites of the Swedish goshawk traps
used for raptor trapping at Sea-Tac were chosen because locations were far removed from
aircraft taxiway traffic, near takeoff zones where aircraft are most vulnerable, and close
in proximity to grassland habitats where raptors would most likely be found hunting for
prey (Figure 1).
18
Chapter 2 Figures
Figure 1. Swedish Goshawk Traps Used For Raptor Trapping at Seattle-Tacoma
International Airport.
19
Chapter 3: Analysis of the Raptor Strike Avoidance Program
To understand the success of the RSAP, it is necessary to analyze the raptor
resight database. The raptor resight data is analyzed to address potential RTHA risks to
aviation. The program has not been assessed since 2005, when the return rate was 0%.
When additional resighting data became abundant after 2005, there was an opportunity to
evaluate the program for this study. Additionally, there are few established raptor
programs at airports and limited research on return rates at Sea-Tac. It is possible that
this research could be applied to other airports with raptor programs. Research on return
rates is necessary because it is lacking within wildlife management programs at most
airports and not all airports have the same internal structure.
The success of the program will be examined by looking at raptor return
rates. Raptor return rates are the number of RTHA resightings within Sea-Tac Airport’s
six-mile airport buffer divided by the total number of RTHAs trapped at Sea-Tac and
relocated to Bow, Washington. A successful RSAP will reflect low return rates (below
15.9%) back to Sea-Tac with few blue-tagged relocated hawks resighted within the sixmile radius of Sea-Tac. An unsuccessful program will reflect high return rates (above
15.9%) back to Sea-Tac with numerous blue-tagged relocated hawks resighted within the
five-mile radius of Sea-Tac.
Geographic Information Systems (GIS) analysis is used to assess distance from
airports. GIS is a relatively new tool used for airport safety that can combine spatially
derived information. GIS spatial information is used to determine where Sea-Tac’s birds
are resighted once they are relocated. Additionally, GIS RTHA resight data from SeaTac is necessary to see how Sea-Tac’s trapped and relocated birds are impacting other
20
small regional airports. The FAA Wildlife Strike Database for struck RTHAs at Sea-Tac
and King County International Airport/Boeing Field (KCIA/BF) will help to determine
strike events before and after the RSAP was first established in 2001. Return rates and
aircraft strikes with RTHAs are the two best indicators to determine the overall success of
the RSAP.
Methodology used in this research also combines citizen science data with GIS
spatial analysis of Sea-Tac’s data and the FAA Wildlife Strike Database strike data (for
Sea-Tac and KCIA/BF) to determine if return rates differ from previous research. If
accepted by Sea-Tac, the methods may support further development of strategies to
minimize raptor-aircraft collisions at other airports in the future.
Materials & Methods
Study Area: Western Washington Airports
Washington State Department of Transportation (WSDOT) releases annual
aviation reports and these reports were relevant to this thesis to determine study design.
Initially thirteen airports were chosen for this research, but after speaking with the United
States Department of Agriculture (USDA) Wildlife Services Wildlife Biologist at
WSDOT the research scope narrowed further to five study site locations. The five study
site locations were determined using page thirty-nine of WSDOT’s Statewide Airports
Profile Reports for 2015:
(1)
Seattle-Tacoma International Airport
(2)
King County International Airport/Boeing Field
(3)
Snohomish County Airport/Paine Field
(4)
Renton Municipal Airport
21
(5)
Bellingham International Airport
These airports were chosen because they have high operations, but also have staff
devoted to bird species identification (Table 1). Methodologies addressed in this section
include data collection patterns between western versus eastern Washington, air traffic
volumes, and data quality.
Raptor Data Collection
Avian surveys began in the summer of 2000 and four avian surveys are
conducted each week in the early mornings and evenings at many locations for twenty
minutes (Figures 3-4). Wildlife biologists at Sea-Tac drive on the airport Perimeter Road
to conduct regular scheduled avian surveys during the week. Avian surveys are
conducted when the vehicle is stopped and the wildlife biologist is on foot in a stationary
position looking through binoculars and/or using a spotting scope for raptors (specifically
RTHAs) and other problematic airport avifauna. The bird species, age, location, time,
perch type, flight activity, and estimated sex are documented by airport biologists. The
RTHA data was the only avian dataset analyzed for this thesis. Additionally, another
portion of the RTHA data was collected by citizen scientists. Citizen scientists were
either trained individuals or random public participants in the community. These
sightings document the location of Sea-Tac’s blue or yellow-tagged RTHAs throughout
western Washington. Each RTHA resight location from the public was emailed to the
Aviation Operations Wildlife Hazard Mitigation & Conservation office.
GIS Data Management for Airport Operations
22
Figure 2 explains the basic GIS data management workflow components of this
research. An Excel spreadsheet was made for the five chosen airports and translocation
site. Web maps were created for Sea-Tac, Paine Field, Renton Municipal, Boeing Field,
and Bellingham airports to depict airport locations.
GIS Data Management for Red-Tailed Hawk Resights
All email resight written locations were compiled into a Microsoft Excel
spreadsheet and uploaded into a web map in ArcGIS (Figure 5). The web map shows
each resight and its associated location. Each resight is symbolized by a blue circular
raptor symbol. A slope terrain layer was added to the map to indicate RTHA elevation
preferences after hawks were trapped at Sea-Tac and relocated to Bow, Washington
(Figure 6). Mean hawk elevations were documented. Next, each resight was categorized
into a preferred habitat type including urban/residential, agricultural, road, forest,
grassland, airport, Puget Sound, river, or wetland (Figure 25).
GIS Spatial Data Analysis of Red-Tailed Hawk Resights
Manager wildlife biologist Steve Osmek identified the five-mile radius
surrounding Sea-Tac Airport as a “danger zone”. This five-mile danger zone indicates
high potential for aircraft collisions with hawks entering crucial flight zones for plane
takeoff and landing. Distance measurements of raptor resights were documented to
determine the proximity of resights to its nearest airport within the five-mile buffer and
resights within five-miles of the translocation site (Figures 13-14 and Figure 20). A
hawk density map was generated to show concentrations of RTHA population densities
23
and indicated population clustering (Figure 22). The density tool shows where RTHA
clusters occur, but does not indicate if statistically significant clustering exists in the data.
Statistical Analysis
A table was created in Excel and pivot table analysis was used to categorize and
count the number of dead, injured, resighted, shot, struck, and trapped RTHAs. Pivot
tables were also used to manipulate the FAA Wildlife Strike Database and query for
struck RTHAs at Sea-Tac and Boeing Field Airports (Figures 23-24). The resight dataset
provided by Sea-Tac Airport was continuous, the research question pertains to
relationships, and there are dependent and independent variables. Additionally, bar
graphs with error bars were used to show the resight distances of each hawk to each
resightings’ nearest airport and translocation site (Figures 15-19 and 21). A box plot
depicts RTHA elevation preference means, which include summary statistics (standard
deviation, standard error of the mean, upper 95% mean, lower 95% mean, and sample
size). The box plot also includes maximum, lower quartile, median, upper quartile, and
minimum value quantiles (Figure 7).
Results
Pivot Table Analysis
Pivot table analysis of the blue tagged hawk resight data revealed 3 dead, 3 dead on
road/runway, 1 injured, 144 resighted, 3 shot, 0 struck and 69 trapped and relocated
RTHAs. The sample size of the blue-tagged RTHAs in the dataset was 59 hawks (n=59).
Repeat Red-Tailed Hawks
24
BL10, BL15, BL50, BR57, BR9, BL31, BL7, and BL82 hawks were considered
repeatedly sighted hawks in the dataset. A repeat bird was a hawk that was resighted
more than four times in the dataset. A story was written for each repeat bird to visually
depict its flight path after the hawk was trapped at Sea-Tac Airport and released north in
Bow, Washington (Figures 27-33).
Habitat Preferences Among Blue-Tagged Red-Tailed Hawks
The dataset revealed that translocated raptors did not have a particular habitat
preference. Of the total resightings, 26% of the hawks favored agricultural habitats,
grasslands followed with 16%, forests and roads (15%), urban/residential areas (14%),
airports (10%), river habitats (2%), Puget Sound (1%) and wetlands accounted for 1%
(Figure 25).
Elevation Preferences Among Blue Tagged Red-Tailed Hawks
The elevation summary statistics for all blue-tagged RTHAs were as follows:
Mean (x̄ = 47.71 meters), standard deviation (s= 47.50 meters), standard error of the
mean (SE= 1.23 meters), upper 95% mean= 50.13, a lower 95% of mean= 45.29 meters,
for a sample size of 59 hawks (n=59). Box plot quantiles revealed a maximum value of
194.93 meters, upper quartile of 88.6 meters, median of 30.44 meters, lower quartile of
8.96 meters, and a minimum value of 1.94 meters (Figure 7).
Birds in Airport Buffers
Zero blue-tagged RTHAs were resighted within the five-mile buffer of Paine Field
(Figure 11). The mean distance of blue-tagged RTHAs to Sea-Tac Airport was 1.15
25
miles of the 8 total blue-tagged birds within the five-mile Sea-Tac Airport danger zone
(Figures 12 and 15). The mean distance of blue-tagged RTHAs to Renton Municipal
Airport was 4.88 miles of the 7 total blue-tagged birds within the five-mile Renton
Municipal Airport danger zone (Figures 12 and 16). The mean distance of blue-tagged
RTHAs to Boeing Field was 3.92 miles of the 11 total blue-tagged birds within the fivemile Boeing Field danger zone (Figures 12 and 17). The mean distance of blue-tagged
RTHAs to Bellingham International Airport was 4.00 miles of the 17 total blue-tagged
birds within the five-mile Bellingham International Airport danger zone (Figures 10 and
18). The mean distance to blue-tagged RTHAs to the translocation site in Bow,
Washington was 3.48 miles of the 23 total blue-tagged raptors within the five-mile
translocation zone.
Program Success Evaluation
Of the total of 144 resighted blue-tagged RTHAs, 8 blue-tagged RHTAs were found
in Sea-Tac’s six-mile airport buffer and 55 birds were trapped so the RTHA return rate
for Sea-Tac was (8/55) 14.55%. 15.9% was the return rate threshold found in the
literature. A return rate lower than 15.9% was a measure of program success.
Discussion
Since there were no resights in the five-mile airport buffer for Paine Field Airport
wildlife biologists have a lower likelihood of risk for Sea-Tac’s birds impacting aircraft
at Paine Field. Paine Field is an important site to discuss because of the lack of sightings
(low observer effort) in its airport buffer, given one would predict this region to have
more resights because of its populated area. Although the void of hawk resightings near
26
Paine Field was surprising, there is the potential that Paine Field has habitat differences.
We thought the habitat would be better for hawks at Paine Field than near other airports
in south Seattle. Paine Field, however, is farther from Interstate-5 (I-5), a corridor where
RTHAs perhaps tend to be sighted there less frequently than the four other airports.
Since Paine Field is located 3.3 miles from I-5, while the other airports are less than a
mile or less from I-5 or a heavily traveled freeway. One would expect sightings near
Paine Field airport, however because it is a populated region and airport employees there
know how to look for and report these marked birds to the Port of Seattle.
Since some resights appear in Sea-Tac, Boeing Field, and Renton Municipal Airport
five-mile buffers, biologists should be more concerned about flight paths of birds to
aircraft at these airports. Since there are not standardized avian survey protocols at all
airports in the Pacific Northwest and not every airport participates in bird strike reporting,
it is difficult to conclude if Sea-Tac’s translocated hawks are directly impacting flight
paths of nearby airports. In the future, it would be beneficial for each airport to have
specialized wildlife staff familiar with avian species identification to conduct
standardized bird surveys on a regular basis as well as improve the ability of airports to
report strikes and sightings into a reliable information system at all airports.
It also appears that there is mortality associated with handling and tagging airport
RTHAs. This may encourage quicker release of the raptors (shorter holding time) from
trapping process, better handling practices in the future by biologists, and more funding
allocated to wildlife programs for future research to assess the impacts of wing tags on
relocated RTHAs. For example, research by Clay (2016) tested the impacts of wing tags
27
on airport snowy owls and this research could be replicated for airport RTHAs at SeaTac.
More outreach and education opportunities for local rural communities by qualified
airport wildlife staff could enhance data quality of the RTHA dataset. For example, more
bird identification courses open to the public and taught year around could improve
species identification within in the RTHA dataset. More eyes looking for RTHAs in less
populated areas will enhance randomization and data quality in rural communities.
Additionally, another area for improvement within the RSAP could include better
data management of the resightings since much of the data is not current and has not been
updated in several months.
28
Chapter 3 Figures
Convert
XLXS file
into a CSV
file
Make a
Folder
Connection
and create a
Geodatabase
in ArcCatelog
Import CSV
Table file into
Geodatabase
Create a
Feature Class
from XY
Table
Set WGS 1984
coordinate
system and drag
new Feature
Class into
ArcMap
Change
Symbology
Completed
Web Map
with all redtailed hawk
resights
Figure 2. GIS Data Management Workflow For Red-Tailed Hawk Resight Data.
Figure 3. Weekly Avian Survey Locations at Seattle-Tacoma International Airport.
29
Figure 4. Tyee Valley Golf Course Avian Survey Locations at Seattle-Tacoma
International Airport.
Figure 5. Blue-Tagged Red-Tailed Hawk Resights From the Raptor Strike Avoidance
Program.
30
Figure 6. Red-Tailed Hawk Elevation Preferences (USGS Terrain_Slope layer).
Figure 7. JMP Output Elevation Preferences Among Blue-Tagged Red-Tailed Hawks.
31
Figure 8. Blue Tagged Red-Tailed Hawk Resights, Five-Mile Airport Buffers, and FiveMile Translocation Site Buffer.
32
Figure 9. Blue-Tagged Red-Tailed Hawk Resights Within Translocation Site Five-Mile
Buffer (n= 18).
Figure 10. Blue-Tagged Red-Tailed Hawk Resights Within Bellingham International
Airport Five-Mile Buffer (n=6).
33
Figure 11. Blue Tagged Red-Tailed Hawk Resights Within Snohomish County/Paine
Field Airport Five-Mile Buffer (n=0).
Figure 12. Blue-Tagged Red-Tailed Hawk Resights Within Seattle-Tacoma International
Airport, King County International Airport/Boeing Field, and Renton Municipal Airport
Five-Mile Buffers (Sea-Tac n=6, Renton n=5, Boeing n=7).
34
Figure 13. Distances of Red-Tailed Hawk Resights to Bellingham International Airport.
Figure 14. Distances of Red-Tailed Hawks Resights from Sea-Tac, Boeing Field, and
Renton Municipal Airports.
35
Figure 15. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles of
Sea-Tac Airport’s Center (n=6).
Figure 16. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles of
Renton Municipal Airport’s Center (n=5).
36
Figure 17. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles of
King County International Airport’s Center (n=7).
Figure 18. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles of
Bellingham International Airport’s Center (n=6).
37
Figure 19. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles of
Paine Field Airport’s Center (n=0).
Figure 20. Distances of Red-Tailed Hawk Resights From Translocation Site in Bow,
Washington.
38
Figure 21. Distance of Translocated Blue-Tagged Red-Tailed Hawks Within 5 Miles of
the Translocation Site’s Center (n=18).
39
Figure 22. Blue Tagged Red-Tailed Hawk Resight Density.
40
Number
of
struck
RTHAs
Red-‐Tailed
Hawk-‐Aircra9
Strikes
at
Sea;le-‐
Tacoma
Interna>onal
Airport
(1995-‐2015)
50
45
40
35
30
25
20
15
10
5
0
1995
2001
2004
2006
2007
2009
2010
2011
2012
2013
2014
2015
Year
Figure 23. Red-Tailed Hawk Strikes With Aircraft at Seattle-Tacoma International
Airport From 1995-2015 (FAA Wildlife Strike Database).
Number
of
struck
RTHAs
Red-‐Tailed
Hawk-‐Aircra9
Strikes
at
King
County
Interna>onal
Airport/Boeing
Field
(2006-‐2011)
12
10
8
6
4
2
0
2006
2010
2011
Year
Figure 24. Red-Tailed Hawk Strikes With Aircraft at King County International
Airport/Boeing Field From 2006, 2010 and 2011 (FAA Wildlife Strike Database).
41
Figure 25. Mean Number of Blue Tagged Red-Tailed Hawk Resights By Habitat Type.
Figure 26. Repeatedly Sighted Translocated Blue-Tagged Red-Tailed Hawks in the
Dataset.
42
Figure 27. BL50’s Flight Path Story Over Time.
Figure 28. BL10’s Flight Path Story Over Time.
43
Figure 29. BL82’s Flight Path Story Over Time.
Figure 30. BL15’s Flight Path Story Over Time.
44
Figure 31. BR57’s Flight Path Story Over Time.
Figure 32. BR9’s Flight Path Story Over Time.
45
Figure 33. BL31’s Flight Path Story Over Time.
Figure 33. BL7’s Flight Path Story Over Time.
46
Chapter 3 Tables
Rank
Airport Name
Operations
Count
(Number
of Airplane
Takeoffs
or
Landings
Per Year)
1
Seattle-Tacoma International Airport
313,954
2
King County International Airport/Boeing Field
259,396
7
Snohomish County/Paine Field Airport
110,270
9
Renton Municipal Airport
80,059
17
Bellingham International Airport
62,783
Table 1. Washington State Department of Transportation Airport Names and Operations.
Table 2. Results Summary.
47
Chapter 4: Conclusions and Recommendations for Future
Research
Conclusions
This study argues that the raptor program is working successfully and encourages
a safer flight path for both air travel passengers and avifauna at Sea-Tac and Boeing Field
based on the O’Hare and Toronto benchmark. Other airports beyond Sea-Tac could
potentially benefit from adapting the Sea-Tac program for RTHA relocation and
resighting to their own relocation and subsequent monitoring (resighting) needs.
Greater data standardization is needed to better answer my research question.
There is certainly room for program improvement through more extensive public
education, outreach opportunities, and bird identification training classes. Further study
of aircraft strike reports could help to relate the relocation/return evidence to aircraft
operations and flight safety, but would require more systematic protocols for both strike
reporting and resighting data collection.
Recommendations for Future Research
A better method of determining elevation preferences would be useful for future
research. For example, using a contouring method for the elevation preference data and
enhanced quantitative analysis in GIS could have been more effective for elevation
spatial analysis. Contouring analysis may be a better way of looking at elevation data
than using the slope data that was used in this thesis.
Additionally, data management for the RTHA resight data could be significantly
improved and more efficient. An area for improvement that Sea-Tac Aviation Operations
48
wildlife staff might consider could be creating a mobile collector application where staff
and public participants can submit hawk resight data from their smartphone device
(which automatically tags bird locations and generates a map of all resights), rather than
wildlife biologists receiving an abundance of resight location emails. Improvements in
data organization are also needed. Improving methods for data collection and reporting
could lead to more precise understanding of program effectiveness and areas where
funding could help to fill in gaps in knowledge.
More substantial research needs to be done on the resident RTHA airport
population to fully understand the role of resident birds at Sea-Tac. For example, SeaTac biologists do not have enough evidence to support the role of resident RTHAs at the
airport. Anecdotally, biologists’ observations have reported that resident birds have
learned aircraft avoidance and scare off other non-resident birds. To fill these
information gaps, Sea-Tac’s future research plans include recapturing resident airport
RTHAs and tracking resident movement using radio telemetry. This future research has
the potential to monitor residents and determine if residents are crossing runways and/or
defending the runway from other avian migrants and juveniles. Additionally, more
resident data and grant funding for radio tags has the potential for more research
questions to be answered.
Improving the program may require targeted funding for improved data collection
methods, relating strike data to raptor presence and quantifying the benefit of relocation
of raptors (like RTHA) to areas far away from airfields in this study, to enable more
widespread outreach and observer training over a larger region, and to capture metrics on
observer effort in areas where birds are not observed.
49
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international airport: a biological approach. 2005 Bird Strike Committee-USA/Canada 7
th
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Appendix
Variables
The variables of interest for this research include elevation preferences, habitat
preferences, hawk distance from the five chosen airports, and return rates. Independent
variables include elevation, habitat type, and distance to nearest airport. Dependent
variables include time, return rates, and hawk sightings. Elevation will be measured in
meters, return rates will be measured in percentages, hawk distance from the chosen
airports will be measured in miles, and habitat types will be documented
categorically. To evaluate the success of the RSAP, Sea-Tac’s RTHA resight data in GIS
will be used calculate the return rates of relocated RTHA.
Detailed GIS Methods
GIS Data Management
The RTHA resighting dataset came from Sea-Tac Airport in an Excel (xlsx)
spreadsheet file. The xlsx file was converted into a comma separated value (CSV) file
because CSV files are compatible for ArcCatalog and ArcMap. The RTHA CSV file
consisted of Object ID, Bird ID, Date, Action, Location, Latitude, Longitude, Comments,
and Originating Airport attributes. The western Washington airport operations data table
was generated from page thirty-nine of Washington Department of Transportation’s
(WSDOT) Statewide Airports Profile Report Based on Information Recorded in 2015
Top Twenty Airports By Operations within WSDOT’s Airport Information System PDF
document. This PDF file supplemented with data from its associated pop-ups for airports
in WSDOT’s Airport Map Application was first converted into an xlsx file and then
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saved as a CSV file. The western Washington airport operations CSV file consisted of
Rank, Civil Airport Name, Latitude, Longitude, Operations Count, Location, Ownership,
and FAA Class attributes. Initially, ArcCatalog was used to manage a geodatabase for
preliminary data management. In ArcCatalog, the RTHA resighting data table and the
western Washington airport operations table were both imported into the geodatabase. A
feature class for the RTHA resighting data and a feature class for the western Washington
airport operations data were created by right clicking on each of the data table icons
(within the geodatabase) and selecting create feature class in ArcCatalog and then
clicking from xy table (one at a time). This allowed the feature classes to become
depicted as points and have associated spatial coordinates in its preview interface. The
two feature layers were then dragged and added into ArcMap and the coordinate system
was set to WGS 1984 for both feature classes (now called layers in ArcMap
language). Next, the ArcMap mxd file was shared as service map package (mpk) file into
ArcGIS Online. From ArcGIS Online, a basemap was added to the map and the legend
became more clearly defined and specialized for the project. The United States
Geological Survey (USGS) layer called ‘Terrain: Slope Map’ was added to ArcGIS
Online as a layer for elevation spatial analysis. Raptor resightings were added as a
feature class to the map with a raptor icon in circular blue circle symbology. Airport
operations were added as a feature class to map with airplane symbology.
GIS Spatial Analysis
A six-mile airport buffer was made around each airport. A yellow buffer was
used for Snohomish County/Paine Field, pink buffer was used for Boeing Field, blue
buffer for Renton Municipal and a green buffer for Sea-Tac. The ArcGIS Online
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Analysis tool was used to gather distances of RTHAs to the nearest airports within the
six-mile airport buffers. After clicking the Analysis tool, ‘Proximity’ was chosen, then
‘Find Nearest’ was clicked. Next, the Red-Tailed Hawk Resightings feature class was
chosen for the ‘(1) Choose the layer from which the nearest locations are found’
option. The Airport Operations in Western Washington feature class was chosen for the
(2) Find the nearest location’ option. A line distance was used for ‘(3) Measure’. Under
‘(4) for each location in the input layer’ three was the ‘limit the number of nearest
locations’ and five miles was the ‘limit the search range’. The density tool was used to
show concentrations of RTHA population densities and depicts where RTHA resight
clusters occur, but does not indicate statistical significance for clustering. In ArcGIS
Online, ‘Analyze patterns’ was chosen to calculate density for the dataset. For option (1),
‘Choose point or line layer from which to calculated density: Red-Tailed Hawk
Resightings’ was chosen. For option (2), Use a count field: no count was chosen. A 50mile search distance was generated and classified by equal intervals for the dataset. Ten
classes were created for the data and square miles were the output units. The drawing
style of the map was changed using the counts and amounts option. In ArcGIS Online,
each RTHA resighting was given a habitat preference. The categories of habitat
preferences were as follows: urban/residential, agricultural, road, forest, grassland,
airport, Puget Sound, river, and wetland. Additionally, mean elevation preferences (in
meters) were documented.
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