A regional model of the eastern cottontail and land-use changes in Illinois

The eastern cottontail (Sylvilagus floridanus) is important in ecological f ood webs as a prey species for a wide variety of predators throughout its r ange, and is also a popular game animal. From 1956 to 1978, the eastern cot tontail is estimated to have declined at least 70% in Illinois and more tha n 90% in the most intensively farmed regions of the state. We describe long -term changes in the index of relative abundance for the eastern cottontail in Illinois in relation to regional patterns of land use. Classification a nd regression trees (CART) analysis was used to analyze county-level change s in 6 land-use variables (row crops, hay, diverted cropland, woodland, sma ll grains, pasture) in relation to the number of cottontails harvested per hunter per day, 1956-69 versus 1982-89. In the early period (1956-69), 78% of the counties had an index of at least 1.50 cottontails . hunter . day(-1 ), compared to only 28% of the counties in the recent period (1982-89). The amounts of pasture, hay, and small grains were positively correlated (P le ss than or equal to 0.01) with the change in cottontail index, and 2 respon se regions were identified with the change in pasture. The region with the least decline in cottontail index had more pasture, hay, and woodland. The stable amount of woodland during recent decades may have moderated the decl ine in cottontails, despite the negative influences of the other land-use c hanges. Long-term changes in the cottontails index in Illinois predictably track changes in farming and geomorphic factors that modify agriculture. Ou r analyses underscore the influence of agriculture on upland wildlife over expansive temporal and spatial scales in North America. influences that are riot necessarily apparent in finer-scale studies.