DOT/FAA/AR-09/62 

Air Traffic Organization 

NextGen & Operations Planning 

Office of Research and 

Technology Development 

Washington, DC 20591 

Evaluation of Trash-Transfer 

Facilities as Bird Attractants 

February 2010 

Final Report 

This document is available to the U.S. public 

through the National Technical Information 

Services (NTIS), Springfield, Virginia 22161. 

U.S. Department of Transportation 

Federal Aviation Administration
NOTICE 

This document is disseminated under the sponsorship of the U.S. 

Department of Transportation in the interest of information exchange. The 

United States Government assumes no liability for the contents or use 

thereof. The United States Government does not endorse products or 

manufacturers. Trade or manufacturer's names appear herein solely 

because they are considered essential to the objective of this report. This 

document does not constitute FAA certification policy. Consult your local 

FAA airports office as to its use. 

This report is available at the Federal Aviation Administration William J. 

Hughes Technical Center’s Full-Text Technical Reports page: 

actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF). 
 Technical Report Documentation Page

1. Report No.

DOT/FAA/AR-09/62

2. Government Accession No. 3. Recipient's Catalog No.

4. Title and Subtitle 

EVALUATION OF TRASH-TRANSFER FACILITIES AS BIRD 

ATTRACTANTS

5. Report Date

February 2010 

6. Performing Organization Code

7. Author(s)

Brian E. Washburn 

8. Performing Organization Report No. 

 

9. Performing Organization Name and Address

United States Department of Agriculture 

Wildlife Services 

National Wildlife Research Center 

10. Work Unit No. (TRAIS)

Columbus Avenue 

Sandusky, OH 44840

11. Contract or Grant No.

 12. Sponsoring Agency Name and Address

U.S. Department of Transportation 

Federal Aviation Administration 

Office of Airport Safety & Standards

13. Type of Report and Period Covered

Final Report 

Washington, DC 20591 14. Sponsoring Agency Code

 AAS-300

15. Supplementary Notes

The Federal Aviation Administration Airport and Aircraft Safety R&D Division Technical Officer was Ryan King. 

16. Abstract

Wildlife collisions (wildlife strikes) with aircraft pose a serious risk to aircraft and cost civil aviation in the United States an 

estimated $490 million annually. Traditional putrescible-waste landfills are very attractive to and are used by many birds, 

especially gulls, creating a hazard to aircraft if located near airports. The Federal Aviation Administration currently recommends 

that the location of municipal solid waste landfills and trash-transfer facilities should not be within 5 statute miles of an airport. 

Little information is available regarding the attractiveness of trash-transfer facilities to wildlife and the potential risk to aviation, 

particularly on a national scale. The objectives of this study were to (1) document wildlife use of trash-transfer facilities and (2) 

determine if the building design or the on-site management characteristics of trash-transfer facilities influence their attractiveness 

to wildlife species. Twenty-nine trash-transfer facilities and four control sites, located in seven states (representative of various 

U.S. geographical regions) were studied. Wildlife (primarily birds) abundance and activity were quantified at each facility and 

control site twice per week for 1 year. Patterns of wildlife use at these facilities differed by building design, season, geographic 

location, and on-site management characteristics. Bird species that are hazardous to aviation commonly observed using trashtransfer facilities (e.g., feeding) included European starlings, gulls, rock pigeons, and crows. 

Overall, the findings from this study demonstrate that wildlife use of trash-transfer facilities, particularly by bird species that are 

hazardous to aviation, can be significant and potentially increase the risk of bird strikes within airport environments. 

Consequently, trash-transfer facilities in close proximity to airport environments should be evaluated on an individual basis to 

determine whether or not they are attractive to or influence the movement patterns of wildlife and if the location of such a facility 

increases the risk to safe aircraft operations. Appropriate wildlife control activities could be conducted at trash-transfer facilities 

to reduce the wildlife attraction and thus decrease the risk of bird strikes associated with those facilities. 

17. Key Words 

Bird strike, Trash-transfer facilities, Wildlife 

18. Distribution Statement 

This document is available to the U.S. public through the 

National Technical Information Service (NTIS), Springfield, 

Virginia 22161.

19. Security Classif. (of this report)

 Unclassified 

20. Security Classif. (of this page)

 Unclassified

21. No. of Pages

 25

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
TABLE OF CONTENTS 

Page 

EXECUTIVE SUMMARY vii 

1. INTRODUCTION 1 

2. METHODS 2 

3. RESULTS 6 

3.1 Wildlife Observations 6 

3.2 Trash-Transfer Facility Characteristics 12 

4. DISCUSSION 13 

5. SUMMARY 15 

6. REFERENCES 15 

iii 
LIST OF FIGURES 

Figure Page 

1 Completely Open Trash-Transfer Facility 3 

2 Three-Sided, Open Trash-Transfer Facility 3 

3 Three-Sided, Trash-Transfer Facility With Bay Doors 4 

4 Semi-Enclosed Trash-Transfer Facility 4 

5 Fully Enclosed Trash-Transfer Facility 5 

6 Mean Number of Birds Observed Using Trash-Transfer Stations and 

Control Sites 9 

7 Mean Number of Birds Observed Each Month Using Trash-Transfer Stations 

and Control Sites 10 

8 Mean Number of Gulls Observed Each Month Using Trash-Transfer 

Stations and Control Sites 10 

9 Mean Number of European Starlings Observed Each Month Using Trash-Transfer 

Stations and Control Sites 11 

iv 
v 

LIST OF TABLES 

Table Page 

1 Trash-Transfer Facilties Summarized by Building Type and State 2 

2 Total Number of Birds Observed and Number of Birds Using Trash-Transfer 

Facilities by Species 7 

3 Mean Number of Birds Using Trash-Transfer Facilties and Control Sites 8 

4 Total Number of Mammals Observed Near and Using the Trash-Transfer Facilities 

and Control Sites 12 
LIST OF ACRONYMS 

AGL Above ground level 

FAA Federal Aviation Administration 

NWRC National Wildlife Research Center 

SAS Statistical Analysis System 

vi 
EXECUTIVE SUMMARY 

Wildlife collisions (wildlife strikes) with aircraft pose a serious risk to aircraft and cost civil 

aviation in the United States an estimated $490 million annually. Traditional putrescible-waste 

landfills are very attractive to, and are used by, many birds (especially gulls) for feeding, 

creating a hazard to aircraft if located near airports. The Federal Aviation Administration 

currently recommends that the location of municipal solid waste landfills and trash-transfer 

facilities should not be within 5 statute miles of an airport. Little information is available 

regarding the attraction of trash-transfer facilities to wildlife and the potential risk to aviation, 

particularly on a national scale. The objectives of this study were to (1) document wildlife use of 

trash-transfer facilities and (2) determine if the building design or the on-site management 

characteristics of the trash-transfer facilities influenced the attractiveness to wildlife species. 

Twenty-nine trash-transfer facilities and four control sites, located in seven states (representative 

of various U.S. geographical regions), were studied. Wildlife (primarily birds) abundance and 

activity were quantified at each facility and control site twice per week for 1 year. 

The movement patterns of wildlife use at these facilities differed by geographic location, 

building design, and on-site management characteristics. Bird species hazardous to aviation 

commonly observed using trash-transfer facilities for feeding included gulls, European starlings, 

rock pigeons, and crows. 

Overall, the findings from this study demonstrate that wildlife use of trash-transfer facilities, 

particularly by bird species hazardous to aviation, can be significant. Thus, trash-transfer 

facilities represent potential wildlife attractants that should be evaluated during wildlife hazard 

assessments and other evaluations within airport environments. In addition, this study suggests 

that several factors, including building design, season, geographic location, and on-site 

management practices can influence wildlife use of trash-transfer facilities. Consequently, trashtransfer facilities in close proximity to airport environments should be evaluated on an individual 

basis to determine whether or not they attract wildlife and if the location of such a facility 

increases the risk to safe aircraft operations. 

vii/viii 
1. INTRODUCTION. 

Collisions between aircraft and wildlife generally have been termed bird or wildlife strikes. 

Wildlife strikes to the civil aviation industry in the United States are both costly (estimated 

annual costs range from $101 to $503 million) and deadly (nine fatalities since 1990 [1]). 

Worldwide, wildlife strikes have caused more than 147 human fatalities and destroyed 

approximately 120 aircraft since 1990 [2 and 3]. Overall, it is estimated that the worldwide cost 

of wildlife strikes to the aviation industry is about $1.2 billion per year [4]. Most wildlife strikes 

occur near airports, with approximately 74% of all bird strikes occurring below 150 m above 

ground level (AGL) and 92% at or below 900 m AGL [1]. Gulls (Larus spp.); waterfowl, such 

as Canada geese (Branta canadensis); hawks (Falconiformes); and owls (Strigiformes); and 

blackbirds (Icteridae)/starlings (Sturnus vulgaris), in particular, are of great concern at airports 

[1, 5, and 6]. Habitat management techniques that reduce birds on and around airports are 

therefore critical for safe airport operations. 

Traditional putrescible-waste landfills are very attractive to and are used by many birds, 

especially gulls, creating a hazard to aircraft if located near airports [7 and 8]. The Federal 

Aviation Administration (FAA) currently recommends that the location of municipal solid waste 

landfills and trash-transfer facilities should not be within 5 statute miles of an airport [9 and 10]. 

There has been an increase in the number of trash-transfer facilities, a trend that will likely 

continue into the future. Consequently, there is a concern that these facilities attract bird species 

hazardous to aviation. If trash-transfer facilities serve as attractants for gulls and other birds, as 

do landfills, the presence of these facilities near airports could increase the risk to aircraft 

operations [7, 11, 12, and 8]. Little information is available regarding how attractive trashtransfer facilities are to birds. Previous studies [4 and 13] compared two waste management 

facilities in one county in both Ohio and New Jersey, respectively, and found that birds used 

trash-transfer facilities less than landfills. Unfortunately, both studies involved only two 

facilities in each county. 

Whether the design of an open-sided, fully enclosed trash-transfer facility is attractive to 

hazardous bird species, particularly at the national scale, is currently unknown. The objective of 

this study was to examine various designs of trash-transfer facilities located in different 

geographic regions of the country (northeast, midwest, southwest, and northwest) by comparing 

more than 20 facilities. This provided important information to the FAA concerning how 

attractive trash-transfer facilities are to bird species. 

The specific objectives of this study were to (1) determine if trash-transfer facilities attract 

wildlife species (primarily birds) and (2) determine if the design characteristics of trash-transfer 

facilities influence the attractiveness to bird species. The null hypothesis is that bird use was not 

different among trash-transfer facilities of various designs. The information provided by this 

study will be useful in determining if and what type of trash-transfer facilities are compatible 

with safe aircraft operations. The National Wildlife Research Center (NWRC) Institutional 

Animal Care and Use Committee approved the procedures before beginning the study. 

1 
2. METHODS. 

Trash-transfer facilities of various designs were inventoried in seven states (Arizona, Ohio, 

Massachusetts, Connecticut, Washington, California, and Missouri), representing different 

geographic regions of the United States. From these inventories, 29 trash-transfer facilities and 

four grocery stores were selected as control sites (table 1). Although there were considerable 

variations in building design, the trash-transfer facilities were categorized as either completely 

open, three-sided open, three-sided bays, semi-enclosed, or fully enclosed. Completely open 

trash-transfer facilities had no walls or were surrounded by a chain-link fence (figure 1). A 

three-sided open trash-transfer facility had three walls and a fourth side was completely open 

(figure 2). Three-sided bay facilities had three walls and a fourth side that had a series of bay 

doors that were left open (figure 3). Semi-enclosed facilities had four walls or chain-link-fenced 

sides with large openings on two sides of the building (figure 4). Fully enclosed trash-transfer 

facilities had four walls with doors large enough for trash trucks to enter or exit the facility 

(figure 5). Control sites (i.e., a grocery store) consisted of a building similar in size and shape to 

trash-transfer facility buildings, but refuse was typically not present. 

Table 1. Trash-Transfer Facilties Summarized by Building Type and State 

Building Type States Number 

Control Arizona, Connecticut, Ohio, 

Washington 

4 

Completely open Massachusetts, Ohio, 

Washington 

3 

Three-sided open Arizona, Washington 5 

Three-sided bays Arizona, Massachusetts, 

Missouri, Ohio, Washington

9 

Semi-enclosed Arizona, California, 

Washington 

6 

Fully enclosed Arizona, Connecticut, 

Massachusetts, Washington 

6 

Total 33 

2 
Figure 1. Completely Open Trash-Transfer Facility 

Figure 2. Three-Sided, Open Trash-Transfer Facility 

3 
Figure 3. Three-Sided, Trash-Transfer Facility With Bay Doors 

Figure 4. Semi-Enclosed Trash-Transfer Facility 

4 
Figure 5. Fully Enclosed Trash-Transfer Facility 

At each facility, Wildlife Services biologists and specialists, under the supervision of an NWRC 

research biologist, conducted 30 minutes of observation (point-counts) that consisted of two 

15-minute counts at two predetermined observation locations. The two observation locations 

were selected to provide a complete view of the facility. Wildlife observations were conducted 

on two randomly chosen days per week (Monday through Friday) for 1 year at each control site 

and trash-transfer facility. In total, each facility was surveyed between 44 and 111 days (mean 

of 94 days) during this period, resulting in an average of 47 hours of observation per facility and 

a total of 1553 hours for the complete study. These surveys were randomly stratified so that the 

surveys were conducted evenly during morning (06:00-11:00), midday (11:00-16:00), and 

evening (16:00-21:00) periods each month at each facility. During each 15-minute survey, the 

presence, number, and behavior of all birds observed within 0.25 mile of the facility or control 

site were recorded. The behavior of birds using the site was recorded by species and categorized 

as (1) pass flying over the site and exhibiting no perceived interest in the site (e.g., soaring 

turkey vultures riding thermal currents); (2) locally flying over or around the site and exhibiting 

a perceived interest in the site (e.g., circular flight pattern with head movement suggesting the 

search for food); (3) loafing on the ground; (4) feeding on the ground; (5) loafing on a refuse 

transport vehicle; (6) feeding on a refuse transport vehicle; (7) loafing on or in the trash-transfer 

facility; and (8) feeding on or in the trash-transfer facility. If the birds exhibited different 

behaviors during the 15-minute period, each activity was recorded. Birds that left the area (i.e., 

flew out of the sight of the observer) and returned during the same 15-minute period were 

considered new birds. 

5 
During each 15-minute survey, wildlife biologists also counted the number of commercial (i.e., 

curbside refuse collection trucks) and private (e.g., pickup trucks and trailers) trucks that were 

present or arrived at the facility. Any instances when refuse “fell off or out of” trash trucks were 

also recorded. In addition, at the start of each survey, the observer assessed the amount of 

uncontained refuse that was outside the building (e.g., on the ground) and available to wildlife 

and recorded this information in four site-rating categories: “none,” “slight,” “moderate,” or 

“heavy.” The percentage of times the amount of uncontained refuse was categorized into each 

site-rating level was calculated for each facility. 

Site-specific management information, including the average tons of refuse per day processed at 

the facility, the size of the building or work area, whether or not rodent control was used on-site, 

and whether or not odor control was used, was obtained from the onsite manager for each trashtransfer facility. In addition, the linear distance (in km) from the facility to the nearest major 

body of water (e.g., ocean, lake, or major river) was determined for each trash-transfer facility 

and control site. 

For the purpose of data analyses and because these observations were not independent, the two 

15-minute surveys conducted at each facility each day were summed to provide a single 30-

minute survey. To limit consideration only to birds that were actually using the trash-transfer 

facilities, birds with the “pass flying,” “locally flying,” “loafing on the ground,” and “feeding on 

the ground” activity codes were removed from the data prior to subsequent statistical analyses. 

The bird observation data were not normally distributed and could not be transformed 

satisfactorily. Therefore, bird use among trash-transfer facilities and control sites by all birds, 

gulls, and European starlings was compared using the Kruskal-Wallis tests [14]. Correlation 

analyses were used to determine if relationships existed between trash-transfer characteristics 

(e.g., building size, distance to major water body) and the mean number of all birds, gulls, and 

European starlings using trash-transfer facilities [14]. Differences were considered statistically 

significant according to a value of P ≤0.05, where P is defined as the probability that the 

correlation observed in the data would have been observed by chance if in fact the correlation 

did not exist. All analyses were conducted using statistical analysis system (SAS) software 

version 9.1 (SAS Institute, Cary, NC). Data are presented as mean ±1 standard error.

3. RESULTS. 

3.1 WILDLIFE OBSERVATIONS. 

At the 29 trash-transfer facilities studied during the 1-year period, 771,586 birds, representing 

108 species, were observed during 2,716 thirty-minute surveys, or on average, 284.1 birds per 

survey. At the four grocery stores (i.e., control sites) studied during the same time period, 

37,115 birds, representing 40 species, were observed during 390 thirty-minute surveys, or on 

average, 95.2 birds per survey. 

European starlings, gulls, rock pigeons, and crows were the bird species/groups most frequently 

observed near and using the trash-transfer facilities and control sites during this study (table 2). 

6 
Starlings and gulls accounted for 78.1% of all birds observed during the study and 78.8% of the 

birds observed actually using the trash-transfer facilities and control sites. 

Table 2. Total Number of Birds Observed and Number of Birds Using Trash-Transfer 

Facilities by Species 

Species/Group 

Total Number 

Observeda

Percent of All 

Birds Observedb

Total Number 

Observed Usingc

Percent of All 

Birds Usingd

European starlings 448,044 55.4 195,340 50.2 

Gulls 183,558 22.7 111,138 28.6 

Rock pigeons 56,674 7.0 33,161 8.5 

Corvids 40,641 5.0 22,839 5.9 

House sparrows 33,911 4.2 12,998 3.3 

Blackbirds 25,661 3.2 8,768 2.3 

Egrets and Herons 5,989 0.7 3,756 1.0 

Doves 5,116 0.6 392 0.1 

Vultures 956 0.1 125 <0.1 

Raptors 538 0.1 25 <0.1 

Other species 7,570 0.9 370 0.1 

Total 808,702 388,920 

a Total number of birds observed (includes all activities) at all facilities 

b Percent of all birds observed (includes all activities) of each species/group c Total number of birds observed using trash-transfer facilities and control buildings (includes only activities 

associated with trash-transfer buildings, trucks, and refuse piles) 

d Percent of all birds observed using trash-transfer facilities and control buildings (includes only activities 

associated with trash-transfer buildings, trucks, and refuse piles) of each species/group 

One fully enclosed trash-transfer facility had an average of 1344.6 birds using the facility per 30-

minute survey, more than 4 times higher than the mean number of birds using any of the other 

fully enclosed facilities (figure 6). The mean number of birds using fully enclosed trash-transfer 

stations was 322.5 ±41.6 birds per survey. The average number of gulls and European starlings 

using fully enclosed trash-transfer stations were 51.4 ±7.0 per survey and 250.4 ±40.0 per 

survey, respectively. Because this facility likely had an overriding influence and biased the data, 

the bird observation data from this facility were removed for the “building type” analyses, and 

when the bird use data were reanalyzed, the mean number of birds using fully enclosed trashtransfer stations was 85.2 ±8.3 birds per survey. The average number of gulls and European 

starlings using fully enclosed trash-transfer stations were then 61.1 ±4.3 per survey and 20.3 

±4.3 per survey, respectively. 

The mean number of birds using trash-transfer facilities of various building designs (ranging 

from 58.0 to 120.0 total birds observed per 30-minute survey) was 2.6 to 5.4 times higher than 

the average number of total birds observed using control sites (0 = 22.1 birds per survey; table 

3). This frequency distribution suggests statistical significance with values of χ

2

 = 286.8 (where 

7 
χ

2 is a statistical calculation used to test how well the distribution of a set of observed data 

matches a theoretical probability distribution. The calculated value is equal to the sum of the 

squares of the differences divided by the expected values) and P <0.0001. Gulls were observed 

using trash-transfer facilities (ranging from 26.9 to 69.7 total gulls observed per 30-minute 

survey) more (χ

2

 = 194.4, P <0.0001) than control sites (0 = 1.2 gulls per survey; see table 3). 

Starlings exhibited a similar pattern; starlings were observed using trash-transfer stations of 

different building designs (ranging from 9.5 to 46.3 total starlings observed per 30-minute 

survey) more (χ

2

 = 485.2, P <0.0001) than control sites (0 = 0.6 starlings per survey; table 3). 

Table 3. Mean Number of Birds Using Trash-Transfer 

Facilties and Control Sites 

Building Type 

All Birdsa

Mean ±SE 

Gullsb, c

Mean ±SE 

European Starlings 

Mean ±SE 

Control 22.1 ±3.2 Ad 1.2 ±0.2 A 0.6 ±0.1 A 

Completely open 89.0 ±6.7 C 26.9 ±3.5 B 46.3 ±5.3 D 

Three-sided, open 58.0 ±4.5 B 37.7 ±4.6 C 9.5 ±1.7 B 

Three-sided, bays 85.1 ±5.1 C 60.2 ±5.7 D 26.1 ±2.4 C 

Semi-enclosed 120.0 ±13.1 C 69.7 ±11.4 D 12.7 ±1.1 B 

Fully enclosede 85.2 ±8.3 C 61.1 ±9.4 D 20.3 ±4.3 C 

a Consists of the total number of birds of all species. 

b Consists of the total number of gulls from 8 species. 

c For analyses of gulls, trash-transfer stations in Arizona and Missouri were excluded as gulls were 

not observed at facilities in these states. 

d Means within the same column with the same letter are not different (P >0.05) according to 

a Kruskal-Wallis test. 

e One fully enclosed trash-transfer facility was excluded from these analyses due to its 

overwhelming influence on the data. 

SE = Standard error of the mean. 

Bird use of trash-transfer facilities varied considerably among those buildings that were of the 

same design (figure 6). The greatest amount of variation in the number of birds using trashtransfer facilities occurred among the fully enclosed trash-transfer facilities. The largest average 

number of birds using trash-transfer facilities were at the aforementioned fully enclosed facility 

(1344.6 ±189.9 birds per survey) and a semi-enclosed trash-transfer facility (630.0 ±63.1 birds 

per survey). In contrast, four trash-transfer facilities (two of the three-sided bays design and two 

of the fully enclosed design) had a mean number of birds using the facility less than 3.0 per 

survey (figure 6). 

8 
Mean No. of Birds per 30-min Survey

0

100

200

300

400

500

600

700

Completely

Open

3-sided

Open

3-sided

Bays

SemienclosedFully

enclosed

Grocery

AZ

OH

MA/CT

WA

MO

CA

= 1344.6

Figure 6. Mean Number of Birds (All Species) Observed Using Trash-Transfer Stations and 

Control Sites 

The average number of birds (all species) observed using trash-transfer sites and control sites 

varied (χ2

 = 200.5, P <0.0001) seasonally (figure 7). Similarly, use of trash-transfer facilities 

and control sites by gulls (χ2 = 211.8, P <0.0001) (figure 8) and European starlings (χ2 = 142.3, 

P <0.0001) (figure 9) followed a similar trend. In general, bird use of trash-transfer facilities 

was highest during the winter months (December to February) and lowest during the summer 

months (May to August). 

9 
0

100

200

300

400

500

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

MONTH

Mean No. of Birds Per 30-min Surve

y Mean No. of Birds Per 30-min Survey 

Figure 7. Mean Number of Birds (All Species) Observed Each Month Using Trash-Transfer 

Stations and Control Sites 

0

100

200

300

400

500

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

MONTH

Mean No. of Birds Per 30-min Survey Mean No. of Birds Per 30-min Survey 

Figure 8. Mean Number of Gulls (Eight Species) Observed Each Month Using Trash-Transfer 

Stations and Control Sites 

10 
0

100

200

300

400

500

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

MONTH

Mean No. of Birds Per 30-min Surve

y Mean No. of Birds Per 30-min Survey 

Figure 9. Mean Number of European Starlings Observed Each Month Using Trash-Transfer 

Stations and Control Sites 

The geographic location of the trash-transfer facilities influenced the amount of bird use that was 

observed during the study. On average, more (χ

2

 = 333.0, P <0.0001) birds per 30-minute 

survey were observed using trash-transfer facilities and control sites in California (630.0 ±2.6 

birds per survey), Massachusetts and Connecticut (321.2 ±42.8 birds per survey), and Ohio 

(106.0 ±6.9 birds per survey) than in Arizona (33.0 ±2.7 birds per survey) and Missouri (36.8 

±9.0 birds per survey); bird use of Washington trash-transfer stations (58.4 ±3.6 birds per 

survey) was intermediate to other states. The average number of gulls at the California trashtransfer facility (462.7 ±60.7 gulls per survey) was greater (χ

2

 = 222.9, P <0.0001) than gull use 

of trash-transfer facilities and control sites in Massachusetts and Connecticut (11.5 ±1.2 gulls per 

survey), Ohio (60.5 ±5.5 gulls per survey), and Washington (26.6 ±2.8 gulls per survey). No 

gulls were observed using trash-transfer stations in Arizona or Missouri. 

Similarly, starling use of trash-transfer facilities and control sites differed (χ2 = 620.7, 

P <0.0001) among states. On average, the highest average number of starlings per survey using 

trash-transfer facilities was in Massachusetts and Connecticut (277.5 ±40.9 starlings per survey), 

whereas trash-transfer stations and control sites in Arizona (2.9 ±0.9 starlings per survey) and 

Washington (9.8 ±0.7 starlings per survey) had the lowest. 

Birds accounted for over 99% of all wildlife observed near and using the trash-transfer facilities 

and control sites during this study. A total of 46 mammals, representing 9 species, were 

observed near or using the trash-transfer facilities or control sites (table 4). Of these 46 

mammals, only 8 (17%) were actually observed using the trash-transfer facilities (e.g., foraging 

on or in the refuse). 

11 
Table 4. Total Number of Mammals Observed Near and Using the Trash-Transfer Facilities 

and Control Sites 

Mammals 

Total 

Number 

Observed 

Total 

Number 

Using 

Coyote (Canis latrans) 2 0 

Desert cottontail rabbit (Sylvilagus auduboni) 2 0 

Feral cat (Felis sylvestris) 12 1 

Feral dog (Canis lupus familiaris) 13 6 

Eastern fox squirrel (Sciurus niger) 4 1 

Raccoon (Procyon lotor) 3 0 

Rat (Rattus sp.) 2 0 

White-tailed deer (Odocoileus virginianus) 7 0 

Woodchuck (Marmota monax) 1 0 

Total 46 8 

3.2 TRASH-TRANSFER FACILITY CHARACTERISTICS. 

At the 29 trash-transfer facilities studied during a 1-year period, a total of 27,113 trash trucks 

were counted. Those trucks included both commercial trash trucks (i.e., curbside refuse 

collection trucks) and private vehicles (e.g., pickup trucks and small trailers). There was an 

average of 10.0 trash trucks (commercial and private) per 30-minute survey. Overall, 

commercial trash trucks accounted for 58.2% of the trucks, whereas private vehicles accounted 

for 41.8%. The proportion of commercial versus private trash trucks differed among facilities; 

trash-transfer facilities in Arizona, Missouri, and Ohio had a high proportion of commercial trash 

trucks (82%-94%), whereas the proportion of private trucks was equal to commercial trucks in 

Massachusetts and Connecticut. At trash-transfer facilities in Washington, private vehicles 

accounted for 67.9% of the total trash trucks. Refuse was observed “falling off” from 

commercial or private trucks only 0.4% of the observations (a total of 129 occasions). 

The average number of total birds using trash-transfer facilities was positively correlated with 

the building size using Pearson’s correlation coefficient (r = 0.445, P = 0.02), tons of trash per 

day (r = 0.602, P <0.001), and the percent of site ratings categorized as “moderate” amount of 

uncontained refuse on the ground (r = 0.419, P = 0.02). Similarly, the average number of gulls 

using trash-transfer facilities was positively correlated with building size (r = 0.547, P = 0.01) 

and the percent of site ratings categorized as “heavy” amounts of refuse on the ground (r = 

0.681, P <0.001). Trash-transfer facility use by European starlings was positively correlated 

with tons of trash per day (r = 0.543, P = 0.002) and the percent of site ratings categorized as 

“moderate” amounts of refuse on the ground (r = 0.381, P = 0.04). Distance to a major water 

body and the percent of site ratings categorized as “none” and “slight” amounts of refuse on the 

ground were not correlated (P>0.05) with bird use of trash-transfer facilities. 

12 
The average number of total birds using trash-transfer facilities with an active rodent control 

program (n = 22; 128.9 ±60.7 birds per survey) was not different (χ

2

 = 0.84, P = 0.36) than the 

average number of total birds using trash-transfer facilities without an active rodent control 

program (n = 7; 139.3 ±82.7 birds per survey). Similarly, the average numbers of total birds 

using trash-transfer facilities with (n = 8; 214.5 ±163.1 birds per survey) and without (n = 21; 

99.8 ±31.8 birds per survey) an odor control program were similar (χ

2

 = 0.50, P = 0.48). 

4. DISCUSSION. 

Trash-transfer stations are facilities where municipal solid waste is unloaded from small trucks 

(e.g., curbside refuse collection trucks) and reloaded into large vehicles (e.g., container trucks) 

for transport to a final disposal site, such as a landfill [15]. Trash-transfer facilities have the 

potential to attract wildlife, in particular species of birds that are hazardous to safe aircraft 

operations. Previous studies of the wildlife use of trash-transfer facilities have been very 

restricted geographically (i.e., within a single county) and in sample size [13, 8, and 16]. 

The number of birds using trash-transfer stations differed among facilities of different building 

type, but not in a consistent pattern. It was originally hypothesized that the number of birds 

actually using trash-transfer facilities would decrease as the trash-transfer buildings became 

more enclosed. Trash-transfer facilities with more open walls would be expected to have more 

bird use as the refuse would potentially be more exposed and available to the birds. However, 

the data from this study do not support that hypothesis. 

The amount of bird use among the trash-transfer facilities varied considerably in this study. Bird 

use of trash-transfer stations was most variable among facilities of the “three-sided, bays,” 

“semi-enclosed,” and “fully enclosed” designs. There were several facilities of these designs 

that had little to no bird use, whereas other facilities of similar design were apparently very 

attractive to and thus heavily used by hazardous birds. Consequently, the findings from this 

study suggest that no one specific building design was associated with limited wildlife use. 

Gulls, consisting of eight individual species, accounted for almost one-third of the birds 

observed using trash-transfer facilities; whereas very few gulls were observed at control sites 

(i.e., grocery stores). Ring-billed gulls (Larus delawarensis), herring gulls (Larus argentatus), 

California gulls (Larus californicus), and western gulls (Larus occidentalis) were the most 

abundant gulls at trash-transfer facilities. The specific gull species present at trash-transfer 

facilities was dependent on the geographic location of those facilities and the geographic 

distribution of the gull species themselves. In addition to loafing on trash-transfer station 

buildings and trash trucks, gulls were often observed actively foraging upon refuse piles within 

the trash-transfer buildings and amongst moving heavy equipment and trucks. About half of all 

the birds observed using trash-transfer facilities were European starlings. Starlings and rock 

pigeons not only loafed on or in trash-transfer buildings and trucks, foraged on refuse piles 

within trash-transfer buildings or on litter outside of the buildings, but they also nested within 

the buildings. Crows were frequently observed using trash-transfer facilities, often loafing or 

feeding on parked trash trucks at the facilities. All these species represent significant hazards to 

safe aircraft operations [1 and 5] and their use of trash-transfer facilities for loafing and foraging 

could increase the risk of bird strikes, particularly if these birds traverse critical airspace 

13 
frequently used by aircraft and across runways as they travel to and from trash-transfer facilities. 

This is especially true for gulls. Studies of herring and ring-billed gulls suggest these birds can 

travel 22 kilometers or more from nesting colonies to landfills and do so several times each day 

[7 and 12]. 

Birds comprised almost all of the wildlife observed at or near trash-transfer facilities during this 

study; few mammals were observed, most of these were feral dogs that fed upon refuse. 

Although the potential for populations of commensal rodents to exist within and around trashtransfer facilities exists, most trash-transfer facilities used a commercial rodent control program 

(e.g., poison baits). Because rodents are nocturnal, these observations probably underestimated 

the numbers present. 

Bird use of trash-transfer facilities varied considerably among seasons during this study. Bird 

use of trash-transfer facilities was greatest during the winter months and least during the summer 

months. This trend was evident for both gulls and European starlings. During the summer 

months, gulls are more likely to exploit food resources from aquatic sources (e.g., fish from 

freshwater lakes or marine environments). Belant, et al. [12], found that breeding herring gulls 

used natural food resources (e.g., fish) rather than foraging on refuse at landfills; however, 

anthropogenic food sources (e.g., garbage at landfills) were found to be important to postbreeding herring gulls. European starlings are likely to be using insect and vegetation (e.g., 

seeds) food resources during the summer months. In contrast, during the winter months, food 

resources for gulls and starlings are more limited and thus anthropogenic food resources might 

be more important and used with greater frequency. Because bird use of trash-transfer facilities 

was clearly influenced by season, assessments (e.g., surveys) of the risk to safe aircraft 

operations associated with trash-transfer facilities should be conducted so that all seasons are 

represented within the assessment period. Minimally, evaluation of trash-transfer stations for 

their attractiveness to wildlife hazardous to aviation should be conducted during the winter 

months. 

The geographic location of a trash-transfer station appears to have a strong influence on the 

amount of bird use of that facility, particularly in reference to birds that are hazardous to 

aviation. Not unexpectedly, gull use of trash-transfer facilities was highest at trash-transfer 

facilities that were near coastal areas or the Great Lakes (e.g., California, Massachusetts, Ohio) 

but nonexistent at trash-transfer facilities in inland areas (e.g., Arizona, Missouri). Crows were 

most abundant and used trash-transfer facilities in the Pacific Northwest and northeast, but 

observed far less frequently at trash-transfer stations in other areas. The total numbers of birds, 

in addition to the species involved, that use a trash-transfer facility for loafing and foraging is 

likely a consequence of the abundance and diversity of bird species present in that geographic 

location. 

The abundance of gulls, European starlings, and all birds using trash-transfer facilities was 

positively related to the proportion of site ratings categorized as having “moderate” or “heavy” 

amounts of refuse on the ground, suggesting that the amount of litter (i.e., uncontained trash) 

outside of the trash-transfer buildings themselves influences the use of these facilities by birds. 

Greater amounts of litter around the facility grounds might be more visible to birds that are 

flying near the facility and thus potentially could attract them to the sites. On-site management 

14 
practices that increase the “cleanliness” of trash-transfer stations, such as periodically removing 

litter and uncontained trash, therefore reduce the use of these facilities by hazardous birds. 

5. SUMMARY. 

Traditional putrescible-waste landfills are very attractive to and are used by many birds, 

especially gulls, creating a hazard to aircraft if located near airports [7 and 8]. The FAA 

currently recommends that the location of municipal solid waste landfills and trash-transfer 

facilities should not be within 5 statute miles of an airport [9 and 10]. There has been an 

increase in the number of trash-transfer facilities, a trend that will likely continue into the future. 

Consequently, there is a concern regarding the probability of these facilities to attract bird 

species hazardous to aviation. If trash-transfer facilities serve as attractants for gulls and other 

birds, as do landfills, the presence of these facilities near airports could increase the risk to 

aircraft operations [7, 11, 12, and 8]. 

The objectives of this study were to (1) document wildlife use of trash-transfer facilities and (2) 

determine if the building design or the on-site management characteristics of the trash-transfer 

facilities influenced the attractiveness to wildlife species. Twenty-nine trash-transfer facilities 

and four control sites, located in seven states (representative of various U.S. geographical 

regions), were studied. Wildlife (primarily birds) abundance and activity were quantified at each 

facility and control site twice per week for 1 year. 

Overall, the findings from this study demonstrate that wildlife use of trash-transfer facilities, 

particularly by bird species considered to be hazardous to aviation, can be significant. Trashtransfer facilities represent potential wildlife attractants that should be evaluated during wildlife 

hazard assessments and other evaluations of wildlife hazards within airport environments. In 

addition, findings from this study suggest that several factors, including building design, season, 

geographic location, and on-site management practices can be important and influence the 

wildlife use of trash-transfer facilities. Consequently, trash-transfer facilities within airport 

environments should be evaluated on an individual basis to determine whether they attract or 

influence the movement patterns of hazardous wildlife and if the location of such a facility 

increases the risk to safe aircraft operations. Appropriate wildlife control activities could be 

conducted at trash-transfer facilities to reduce their attractiveness to hazardous wildlife and thus 

decrease the risk of bird strikes associated with those facilities. 

6. REFERENCES. 

1. Cleary, E.C., Dolbeer, R.A., and Wright, S.E., “Wildlife Strikes to Civilian Aircraft in the 

United States, 1990-2005,” U.S. Department of Transportation, Federal Aviation 

Administration, Wildlife Aircraft Strike Database Serial Report Number 12, Washington, 

DC, 2006. 

2. Richardson, W.J. and West, T., “Serious Birdstrike Accidents to Military Aircraft: 

Updated List and Summary,” Proceedings of the 25th International Bird Strike 

Committee, Vol. 25, 2000, pp. 67-98. 

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3. Thorpe, J., “Fatalities and Destroyed Aircraft due to Bird Strikes, 1912-2002,” 

Proceedings of the International Bird Strike Committee, Vol. 26, 2003, pp. 85-113. 

4. Allan, J.R., “The Costs of Bird Strikes and Bird Strike Prevention,” Proceedings of the 

Third NWRC Special Symposium: Human Conflicts With Wildlife: Economic 

Considerations, USDA/National Wildlife Research Center, Ft. Collins, Colorado, 2002, 

pp. 147-153. 

5. Dolbeer, R.A., Wright, S.E., and Cleary, E.C., “Ranking the Hazard Level of Wildlife 

Species to Aviation,” Wildlife Society Bulletin, Vol. 28, 2000, pp. 372-378. 

6. Wright, S.E., “Canada Geese: Flying Elephants we Must Avoid!” FAA Aviation News, 

Vol. 36, 1997, pp. 1-5. 

7. Belant, J.L., Ickes, S.K., and Seamans, T.W., “Importance of Landfills to Urban-Nesting 

Herring and Ring-Billed Gulls,” Landscape and Urban Planning, Vol. 43, 1998, 

pp. 11-19. 

8. Gabrey, S.W., “Bird and Small Mammal Abundance at Four Types of WasteManagement Facilities in Northeast Ohio,” Landscape and Urban Planning, Vol. 37, 

1997, pp. 223-233. 

9. Federal Aviation Administration, “Construction or Establishment of Landfills Near 

Public Airports,” U.S. Department of Transportation, Federal Aviation Administration, 

Advisory Circular 150/5200-34, Washington, DC, 2000. 

10. Federal Aviation Administration, “Hazardous Wildlife Attractants on or Near Airports,” 

U.S. Department of Transportation, Federal Aviation Administration, Advisory Circular 

150/5200-33A, Washington, DC, 2004. 

11. Belant, J.L., Seamans, T.W., Gabrey, S.W., and Dolbeer, R.A., “Abundance of Gulls and 

Other Birds at Landfills in Northern Ohio,” American Midland Naturalist, Vol. 134, 

1995, pp. 30-40. 

12. Belant, J.L., Seamans, T.W., Gabrey, S.W., and Ickes, S.K., “Importance of Landfills 

to Nesting Herring Gulls,” Condor, Vol. 95, 1993, pp. 817-830. 

13. Caccamise, D.F., Reed, L.M., and Romanowski, J., “Bird Strike Hazards and Waste 

Management Facilities in Urban Landscapes,” Proceedings of the International Bird 

Strike Committee, Vol. 23, 1996, pp. 247-266. 

14. Zar, J.H., Biostatistical Analyses, 3rd edition, Prentice-Hall Publishing Company, Upper 

Saddle River, New Jersey, 1996. 
15. Environmental Protection Agency, “Waste Transfer Stations: Involved Citizens Make 

the Difference,” U.S. Environmental Protection Agency, Solid Waste and Emergency 

Response, EPA530-K-01-003, Washington, DC, 2001. 

16. Stevens, M.R., Schafer, L.M., and Washburn, B.E., “Trash and Water: Managing OnAirport Wildlife Attractants at Paine Field, Washington,” Proceedings of the 7th Joint 

Meeting of Bird Strike Committee USA/Canada, Vancouver, Canada, August 15-18, 

2005. 

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