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 AdministrationNOTICE

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the in terest of information exchange. The United States Government assumes no liability for the contents or use thereof. The United States Govern ment does not endorse products or manufacturers. Trade or manufactu rer's names appear herein solely because they are considered essential to the objective of this report. This document does not constitute FAA certif ication policy. Consult your local FAA airports office as to its use.

This report is available at the Feder al 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 Stat es an estimated $490 million annually. Traditional put rescible-waste landfills are very attrac tive to and are used by many birds, especially gulls, creating a hazard to aircra ft if located near airports. The Fede ral Aviation Administration currently recomm ends that the location of municipal solid waste landfills and trash-transfer facilities should not be within 5 statute miles of an a irport. Little information is available regarding the attractiveness of trash-transfer facilities to w ildlife 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 ch aracteristics of trash-transfer facilities influence their attract iveness to wildlife species. Twenty-nine trash-tran sfer facilities and four control sites, located in seven states (representative of various U.S. geographical regions) were studied. Wildlife (primarily birds) abundance and activity we re quantified at each facility an d control site twice per week for 1 year. Patterns of wildlife use at these facilities differed by building design, season, geog raphic location, and on-site management characteristics. Bird speci es 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 us e of trash-transfer facilities, particularly by bird species that are hazardous to aviation, can be significant a nd potentially increase the risk of bird strikes within airport environments. Consequently, trash-transfer f acilities in close proximity to airport environmen ts should be evaluated on an individual basis t o determine whether or not they are attractive to or influence the movement patterns of wildlife and if the location of such a fa cility increases the risk to safe aircraft opera tions. Appropriate wildlife control activitie s could be conducted at trash-transfer f acilities
to reduce the wildlife attraction and thus decrease the ri sk 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 authorizedTABLE 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

iiiLIST 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 Ob served Each Month Using Trash-Transfer
Stations and Control Sites 11

ivv 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 12LIST OF ACRONYMS

AGL Above ground level
FAA Federal Aviation Administration
NWRC National Wildlife Research Center SAS Statistical Analysis System

viEXECUTIVE 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 muni cipal solid waste landfills and trash-transfer
facilities should not be within 5 st atute miles of an airport. Little information is available regarding the attraction of trash-transfer facilitie s 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 infl uenced the attractiveness to wildlife species. Twenty-nine trash-transfer facilities and four contro l sites, located in seven states (representative of various U.S. geographical regions), were st udied. 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 tr ash-transfer facilities, particularly by bird species hazardous to aviati on, 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 de sign, season, geographic location, and on-site management practices can influence wildlife use oftrash-transfer facilities. Consequently, trashtransfer facilities in close proxim ity 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/viii1. 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 mo re than 147 human fatalities and destroyed approximately 120 aircraft since 1990 [2 and 3]. Ov erall, it is estimated th at the worldwide cost
of wildlife strikes to the aviati on 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 (F alconiformes); and owls (Strigiformes); and blackbirds (Icteridae)/starlings (Sturnus vulgaris), in particular, are of great concern at airports [1, 5, and 6]. Habitat management technique s 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 w ithin 5 statute miles of an airport [9 and 10].
There has been an increase in the number of tr ash-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 se rve as attractants for gulls and other birds, as do landfills, the presence of these facilities near ai rports 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 studi es [4 and 13] compared two waste management facilities in one county in both Ohio and New Je rsey, 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 nati onal 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, mi dwest, southwest, and northwest) by comparing more than 20 facilities. This provided impor tant 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 speci es. The null hypothesis is that bird use was not different among trash-transfer facilities of vari ous 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.

12. METHODS

.
Trash-transfer facilities of various designs were inventoried in seven states (Arizona, Ohio, Massachusetts, Connecticut, Washington, Califor nia, and Missouri), representing different geographic regions of the United States. From th ese inventories, 29 trash-transfer facilities and four grocery stores were selected as control s ites (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-enc losed, 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 thr ee 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-enclo sed facilities had four walls or chain-link-fenced sides with large openings on two sides of the build ing (figure 4). Fully enclosed trash-transfer facilities had four walls with doors large enough fo r trash trucks to enter or exit the facility (figure 5). Control sites (i.e., a grocery store) c onsisted 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

2Figure 1. Completely Open Trash-Transfer Facility

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

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

Figure 4. Semi-Enclosed Trash-Transfer Facility

4Figure 5. Fully Enclosed Trash-Transfer Facility

At each facility, Wildlife Services biologists a nd specialists, under the supervision of an NWRC research biologist, conducted 30 minutes of obser vation (point-counts) that consisted of two 15-minute counts at two predetermined observati on 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 th rough Friday) for 1 year at each control site and trash-transfer facility. In total, each f acility was surveyed between 44 and 111 days (mean of 94 days) during this period, resulting in an av erage of 47 hours of obser vation 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 morn ing (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 obser ved within 0.25 mile of the facility or control
site were recorded. The behavior of birds usi ng 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) loca lly flying over or around the site and exhibiting a perceived interest in the site (e.g., circular f light 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-transf er facility. If the birds exhibited different behaviors during the 15-minute period, each activity wa s recorded. Birds that left the area (i.e., flew out of the sight of the observer) and re turned during the same 15-minute period were
considered new birds.

5During 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 wh en 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 buildi ng (e.g., on the ground) and available to wildlife
and recorded this information in four site-rati ng 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) wa s determined for each trash-transfer facility
and control site.

For the purpose of data analyses and because th ese 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,” “loca lly flying,” “loafing on the ground,” and “feeding on the ground” activity codes were removed from the da ta prior to subsequent statistical analyses. The bird observation data were not normally distributed and could not be transformed satisfactorily. Therefore, bird use among trash-tr ansfer facilities and control sites by all birds, gulls, and European starlings was compared us ing the Kruskal-Wallis tests [14]. Correlation analyses were used to determine if relationshi ps 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 usi ng statistical analysis system (SAS) software version 9.1 (SAS Institute, Cary, NC). Data are presented as mean ±1 standard error.

3. RESULTS

.

3.1 WI LDLIFE OBSERVATIONS

.

At the 29 trash-transfer facilities studied dur ing the 1-year period, 771,586 birds, representing 108 species, were observed during 2,716 thirty-mi nute surveys, or on average, 284.1 birds per survey. At the four grocery stores (i.e., c ontrol sites) studied during the same time period, 37,115 birds, representing 40 species, were obser ved 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 facilitie s and control sites during this study (table 2).

6Starlings 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
Observed a Percent of All
Birds Observed b Total Number Observed Using c Percent of All Birds Using d

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 (include s 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 re fuse 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 th e mean number of birds using any of the other fully enclosed facilities (figure 6). The mean numbe r of birds using fully enclosed trash-transfer stations was 322.5 ±41.6 birds per survey. The av erage 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 m ean number of birds using fully enclosed trashtransfer stations was 85.2 ±8.3 birds per surve y. 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

7χ 2 is a statistical calculation used to test how well the distribution of a set of observed data matches a theoretical probability distribution. Th e 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 we re 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 Birds a
Mean ±SE Gulls b, c

Mean ±SE European Starlings
Mean ±SE

Control 22.1 ±3.2 A d 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 enclosed e 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-transf er stations in Arizona and Miss ouri 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 fac ilities 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-enclo sed trash-transfer facility (630.0 ±63.1 birds per survey). In contrast, four trash-transfer f acilities (two of the three-sided bays design and two of the fully enclosed design) had a mean numbe r of birds using the facility less than 3.0 per survey (figure 6).

8Mean No. of Birds per 30-min Survey

0 100 200 300 400 500 600 700

Completely Open 3-sided Open 3-sided Bays Semienclosed Fully
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 ( χ 2 = 200.5, P <0.0001) seasonally (figure 7). Similarly, use of trash-transfer facilities and control sites by gulls ( χ 2 = 211.8, P <0.0001) (figure 8) and European starlings ( χ 2 = 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 (Decembe r to February) and lowest during the summer months (May to August).

90 100 200 300 400 500

Jan Feb Mar Ap r May Jun J ul Aug Sep Oct No v Dec

MONTHMean No. of Birds Per 30-min SurveyMean 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 A pr May Jun Jul Aug S e

p Oct Nov Dec

MONTHMean No. of Birds Per 30-min SurveyMean 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

100 100 200 300 400 500

Ja n Fe b Ma r Ap r M a

y Ju n Jul A u

g S e

p O c t No v De c

MONTHMean No. of Birds Per 30-min SurveyMean 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 fac ilities 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 f acilities 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 Washingt on 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 c ontrol sites in Massachusetts and Connecticut (11.5 ±1.2 gulls per survey), Ohio (60.5 ±5.5 gulls per survey), a nd 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 site s 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 observe d 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 fac ilities or control sites (table 4). Of these 46 mammals, only 8 (17%) were actually observed us ing the trash-transfer facilities (e.g., foraging on or in the refuse).

11Table 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 TR ASH-TRANSFER FACILITY CHARACTERISTICS

.

At the 29 trash-transfer facilities studied duri ng a 1-year period, a total of 27,113 trash trucks
were counted. Those trucks included both comme rcial trash trucks (i.e., curbside refuse collection trucks) and private vehicles (e.g., pic kup 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 th e 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, a nd Ohio had a high proportion of commercial trash trucks (82%-94%), whereas the proportion of priv ate trucks was equal to commercial trucks in
Massachusetts and Connecticut. At trash-tran sfer 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 pos itively 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 Eu ropean 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.

12The average number of total birds using trash-tr ansfer facilities with an active rodent control program ( n = 22; 128.9 ±60.7 birds per su rvey) was not different ( χ 2 = 0.84, P = 0.36) than the average number of total birds using trash-transf er facilities without an active rodent control program ( n = 7; 139.3 ±82.7 birds per survey). Simila rly, 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. DI SCUSSION

.
Trash-transfer stations are facilities where municipal solid waste is unloaded from small trucks (e.g., curbside refuse collection trucks) and reload ed 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 us e of trash-transfer facilities have been very restricted geographically (i.e., within a singl e county) and in sample size [13, 8, and 16].

The number of birds using trash-transfer stati ons 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 decr ease as the trash-transfer buildings became
more enclosed. Trash-transfer facilities with mo re 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 f acilities varied considerably in this study. Bird
use of trash-transfer stations was most vari able 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 f acilities 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 wester n 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 loca tion 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 obs erved actively foraging upon refuse piles within the trash-transfer buildings and amongst moving h eavy 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 us ing 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

13frequently used by aircraft and across runways as th ey 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 col onies 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 th ese 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 f acilities used a commercial rodent control program (e.g., poison baits). Because rodents are nocturn al, these observations probably underestimated the numbers present.

Bird use of trash-transfer facilities varied c onsiderably among seasons during this study. Bird use of trash-transfer facilities was greatest duri ng 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 re sources from aquatic sources (e.g., fish from freshwater lakes or marine environments). Be lant, 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 la ndfills) 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 th e winter months, food resources for gulls and starlings are more limited and thus anthropogenic food resources might be more important and used with greater frequenc y. 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 fac ilities should be conducted so that all seasons are represented within the assessment period. Minima lly, 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 sta tion 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-tran sfer 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 in land areas (e.g., Arizona, Missouri). Crows were
most abundant and used trash-transfer facilitie s in the Pacific Northwest and northeast, but observed far less frequently at trash-transfer stati ons in other areas. The total numbers of birds, in addition to the species involved, that use a tr ash-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 a ttract them to the sites. On-site management

14practices 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. SU MMARY

.
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 muni cipal 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 fac ilities 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-tr ansfer facilities and (2) determine if the building design or the on-site ma nagement characteristics of the trash-transfer
facilities influenced the attractiveness to wildlif e species. Twenty-nine trash-transfer facilities and four control sites, located in seven stat es (representative of various U.S. geographical regions), were studied. Wildlife (primarily bird s) 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 tr ash-transfer facilities, particularly by bird species considered to be hazardous to aviation, can be significant. Trashtransfer facilities represent poten tial wildlife attractants that should be evaluated during wildlife
hazard assessments and other evaluations of wild life 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. Conse quently, 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 w ildlife and if the locati on 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. RE FERENCES

.

1. Cleary, E.C., Dolbeer, R.A., and Wright, S.E., “W ildlife Strikes to Civilian Aircraft in the United States, 1990-2005,” U.S. Department of Transportation, Federal Aviation Administration, Wildlife Aircraft Strike Da tabase Serial Report Number 12, Washington, DC, 2006.

2. Richardson, W.J. and West, T., “Serious Bird strike Accidents to Military Aircraft: Updated List and Summary,” Proceedings of the 25 th International Bird Strike
Committee , Vol. 25, 2000, pp. 67-98.

1516 3. Thorpe, J., “Fatalities and Destroyed Ai rcraft 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 St rikes and Bird Strike Prevention,” Proceedings of the Third NWRC Special Symposium: Hum an 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, “Constructi on or Establishment of Landfills Near Public Airports,” U.S. Department of Tr ansportation, Federal Aviation Administration, Advisory Circular 150/5200-34, Washington, DC, 2000.

10. Federal Aviation Administration, “Hazardous Wild life 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 Romanowsk i, 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, 3 rd edition , Prentice-Hall Publishing Company, Upper Saddle River, New Jersey, 1996.15. Environmental Protection Agency, “Waste Tr ansfer Stations: Involved Citizens Make the Difference,” U.S. Environmental Prot ection Agency, Solid Waste and Emergency Response, EPA530-K-01-003, Washington, DC, 2001.

16. Stevens, M.R., Schafer, L.M., and Washbur n, B.E., “Trash and Water: Managing OnAirport Wildlife Attractants at Paine Field, Washington,” Proceedings of the 7 th Joint Meeting of Bird Strike Committee USA/Canada , Vancouver, Canada, August 15-18,
2005.

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