Abstract
Little information exists on the importance of landfills to urban gulls and the influence landfills have on the establishment of urban-nesting gull colonies. Thus, there is critical need for data to determine factors contributing to increasing populations of urban gulls. Our objectives were to determine the importance of landfills to the reproductive success, diet, and movements (via radio telemetry) of urban-nesting herring gulls (
Larus argentatus) and ring-billed gulls (
L.
delawarensis) in northern Ohio. Hatch success of herring gulls (198 breeding pairs) and ring-billed gulls (4502 breeding pairs) at urban-nesting colonies was ≥41% lower than hatch success of traditional Great Lakes nesting colonies and more closely approximated hatch success of other urban-nesting colonies. Based on diet and habitat use, ring-billed gulls appeared more dependent on landfills than did herring gulls. Anthropogenic food, primarily from three landfills, was the major component of the diets of ring-billed gulls, whereas fish, primarily from Lake Erie, was used more extensively by herring gulls. On average, adult (25
km) and hatching-year (24
km) ring-billed gulls were located farther from their nesting colony than were adult (18
km) or hatching-year (12
km) herring gulls. Habitat use by hatching-year gulls of both species was similar to habitat use by adult conspecifics. Landfills contain a dependable source of food for urban-nesting gulls. Thus, size and distribution of urban-nesting gull colonies are likely to continue increasing, provided adequate anthropogenic food and colony sites remain available.