ABUNDANCE OF GULLS AND OTHER BIRDS AT LANDFILLS IN NORTHERN OHIO

We estimated the abundance of birds at three landfills in northern Ohio from May 1991-July 1992 recording 699,350 individuals of 42 species. Gulls (Larus spp.) comprised 94.5% of the birds recorded followed by European starlings (Sturnus vulgaris, 5.0%) and turkey vultures (Cathartes aura, 0.3%). Gulls were primarily of two species, ring-billed (L. delawarensis, 74.49%) and herring (L. argemtatis, 25.50%). The mean number of gulls per observation during July-January was at least five times the mean number observed during other months. The combined monthly mean number of gulls at the three landfills peaked in August (>4000 birds), with gulls virtually absent in February. Total numbers, species composition and age composition of gulls varied seasonally in response to breeding, foraging and migratory behavior of local and regional populations. More than 98% of gulls observed were recorded on or within 30 m of the ground. A mean of one +/- 17 (SD) gulls per observation were observed soaring at >300 m elevation over the landfills. Species composition and seasonal abundance of birds varied considerably among the three landfills, even though they were operated similarly and were in dose proximity to each other. To adequately assess the use of landfills by gulls and other birds, studies lasting greater than or equal to 1 year are required. Furthermore, the results from one landfill cannot necessarily be extrapolated to other landfills in the same region.