Reduction in the Eastern Limit of the Range of the Franklin's Ground Squirrel (Spermophilus franklinii)

Abstract

-The eastern range limit of the Franklin's ground squirrel (Spermophilus franklinii) in North America extends into northwest Indiana. We determined the species' current range in Indiana using live traps at 370 survey sites in 20 counties from July 1984 to August 1990. We captured 120 Franklin's ground squirrels in 5161 trap days at 36 (9.7%) sites. Its current distribution is limited to nine of the westernmost counties in northwest Indiana. No squirrels were found in eight counties at the eastern periphery of the species' previously known range. Mean capture rate and frequency of squirrel occurrence relative to trapping effort did not differ among four land use types. Franklin's ground squirrels were not found in many seemingly suitable areas. Research is needed to identify preferred habitat and to aid in managing this species. Urban development, agricultural expansion, and conversion to row crops may have reduced the amount of grassland habitat available to support Franklin's ground squirrels.