Background
Due to abundant food resources, landfills commonly attract foraging birds, including gulls, vultures, crows, and blackbirds[3]. Large congregations of birds attracted to landfills can cause unsightly conditions, facilitate the transmission of diseases, and cause conflicts with nearby aircraft[1]. Problems with nuisance birds at landfills have necessitated management strategies to limit bird access to landfill food resources.
A southeastern landfill adjacent to a nearby airport was undergoing a future expansion, and there was concern that expansion could alter or increase bird use. We designed a bird survey for the landfill and surrounding areas using bird point counts to accomplish the following objectives:
- Establish baseline bird abundance at the landfill before any expansion occurs
- Develop bird control management strategies tailored to the birds observed at the landfill
Bird Study Methods
Using point counts[2], we surveyed the landfill’s working face (where trash is openly exposed) and three surrounding locations once per month for six months, from September to February. Bird activity was monitored throughout the day to understand how activity patterns changed over time. We recorded behavior observations, including perching on the working face, perching off the working face, or in flight. For birds observed in flight, an approximate flight direction was assigned to each observation.
Because we did not survey birds during the spring and summer, we do not know how bird species composition and abundance were different during this time. Continuous monitoring for a full year would have provided a more thorough inventory of the birds that use the landfill throughout the year.
Findings
Fifty-eight species were observed at the landfill, with gulls being 71% of the observations, blackbirds 16%, and crows 6%; other species groups comprised the remaining 7% of observations.
Twenty-six species were observed on the landfill’s working face. Bird activity was lowest during the early morning and highest in the late morning and early afternoon. In the morning, birds typically arrived from the northeast and east and departed in the late afternoon to the northwest and southwest.
Fifty-one species were observed away from the working face, with 60% of observations being gulls, 16% were blackbirds, 10% were crows, and 10% were songbirds. Flight behavior away from the working face was similar to what occurred at the working face.
Bird control and mitigation suggestions
Given that gulls were the most frequently observed species group, we suggested an integrated approach for a bird control plan. Large gull numbers can contaminate water supplies with droppings, be a hazard to aircraft, take endangered species, and create nuisance conditions at parks and residential neighborhoods.
With the major gull attractant at the landfill being food and water (from areas away from the working face), the bird control plan recommends the following actions to reduce gull (and other bird) activity at the landfill:
- Minimizing the size of the active working face
- Installing effigies of the target species to discourage their use of the landfill
- Harassing birds with pyrotechnics during high-activity periods
- Discouraging bird use of the nearby water by installing an overhead wire grid or Bird Balls®.
These recommendations should ensure reliable landfill operations while minimizing nuisance bird activity and impacts to the nearby airport.
References
[1] Nelson, M., S. H. Jones, C. Edwards, and J. C. Ellis. 2008. Characterization of Escherichia coli populations from gulls, landfill trash, and wastewater using ribotyping. Diseases of Aquatic Organisms 81:53-63.
[2] Ralph, C. J., J. R. Sauer, and S. Droege. 1995. Monitoring bird populations by point counts. General Technical Report, United States Department of Agriculture, Forest Service, Albany, California, USA.
[3] Restani, M., J. M. Marzluff, and R. E. Yates. 2001. Effects of anthropogenic food sources on movements, survivorship, and sociality of common ravens in the Arctic. Condor 103:399-404.
