Museum collections of mammals corroborate the exceptional decline of prairie habitat in the Chicago region

The prairie deer mouse (Peromyscus maniculatus bairdii) was more common tha n the white-footed mouse (P. leucopus) in museum collections from the 6 Ill inois counties of the Chicago region before 1920 but constitutes only 5% of specimens deposited since 1970. Because white-footed mouse prefers woody v egetation and because prairie deer mouse is limited to prairie or large ope n habitats, the change in proportion is likely driven by a disproportionate loss of prairie among remaining natural habitat and increases in woody veg etation within grasslands. The decline of the prairie vole (Microtus ochrog aster) relative to the meadow vole (M. pennsylvanicus) and the lack of rece nt specimens of Franklin's ground squirrel (Spermophilus franklinii) corrob orate the hypothesis that prairie habitats have declined much more so than wooded habitats in the Chicago region. Based on extinction models using mus eum records, it is probable that S. franklinii is already locally extirpate d. Regression analysis suggests the white-footed mouse will be the only loc al Peromyscus in 0-140 years.