PARENT SESSION
Poster Session #30: Long-Term Ecological Research.
Wednesday, August 8, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall

Habitat use and area sensitivity of birds in a highly fragmented Illinois landscape: The Critical Trends Assessment Program.

Bailey, Steven¹, Jack, Rhetta¹, ¹

ABSTRACT- Many bird species are declining over large segments of their ranges due to habitat loss, degradation, fragmentation, and cowbird parasitism. In Illinois, the Critical Trends Assessment Program (CTAP), a statewide monitoring project, was established to understand these issues. A total of 450 sites (150 in forest, wetland, and grassland over five years) were randomly selected for monitoring. Between 1997-2000, 110 forest, 109 wetland, and 97 grassland sites have been monitored. Detection rates were used to determine frequency of use of sites by area-sensitive, habitat dependent species. In forests, only three of these species were detected at a rate less than 3.6%. The highest rate was only 16.3%, with moderately sensitive species detected at much higher rates (22.7–88.2%). One of the greatest detection rates was for Brown-headed Cowbirds, a nest parasite, at 76.3%. An average of only 1.8 grassland dependent species were detected in grasslands, a very low value when compared with historical data for Illinois. For grassland and forest species, the smaller a habitat patch becomes, the fewer area-sensitive species it supported. Only 22 wetland-dependent species were detected, with 1.3 of these species found per wetland site. Approximately 51% of wetland sites supported no wetland-dependent species. Of the wetlands that supported wetland dependent species, 66% contained more than one species. The low detection rates of area-sensitive species for all habitat types indicates the degraded and fragmented nature of those habitats.

KEY WORDS: habitats, birds, Illinois, monitoring