Illinois Natural History Survey - University of Illinois

Franklin's Ground Squirrel: An Increasingly Rare Prairie Mammal

While thirteen-lined ground squirrels are a common sight on roadsides, golf courses, cemeteries, and lawns in northern and central Illinois, the other ground squirrel that lives in Illinois is less familiar. Franklin's ground squirrel, also called the gray gopher or whistle pig (because of its vocalizations), is primarily an inhabitant of the northern Great Plains from Alberta and Saskatchewan to Kansas and Missouri, but its range extends eastward through northern and central Illinois into northwestern Indiana.

It is considered a characteristic species of tallgrass and mid-grass prairie. Franklin's ground squirrels occupy not only the open prairie, but also woodland edges, forest openings, thickets, and marsh and bog borders. Their most important habitat requirement is a tall, dense cover of grasses, forbs, shrubs, and even small trees; they avoid the short grass of closely grazed pastures or mowed areas. In regions of intensive agriculture suitable habitat remains in fencerows, old fields, roadsides (if not mowed frequently), cemetery prairies, ditch banks, and railroad rights-of-way. Railroad embankments are considered especially important because few other places may have dense, undisturbed vegetation.

Franklin's ground squirrel, Spermophilus franklinii.

As true hibernators Franklin's ground squirrels are active less than half the year. They typically emerge from hibernation during April. Breeding occurs shortly thereafter and females give birth to a single litter (usually six to nine pups) from late May to mid-June. Franklin's ground squirrels are strictly diurnal and may be the most carnivorous of the ground squirrels. Their diet includes green plants, seeds, fruit, insects, amphibians, bird eggs, young birds and mammals, and carrion. They can be significant predators of duck eggs in the Prairie Pothole region and also cause some crop damage. Adults enter hibernation as early as July, but young squirrels have been collected in Illinois as late as mid-November. Overall, this species may spend less than 10% of its life aboveground.

Prior to European settlement, prairie covered 60% of Illinois, but more than 99% of our native prairie has been lost to agriculture and urbanization. Although there are historical records of Franklin's ground squirrel from numerous locations in northern and central Illinois, recent information about its distribution and abundance is limited. In 1986 University of Wisconsin researchers surveyed Illinois wildlife managers, natural heritage biologists, and naturalists; they reported sightings from 22 locations in 16 counties. Many biologists have speculated that Franklin's ground squirrel is becoming increasingly uncommon in the eastern portion of its range and its distribution in Indiana apparently has shrunk. Accordingly, Franklin's ground squirrel is listed as an endangered species in Indiana and a species of special concern in Wisconsin.

To assess the status of Franklin's ground squirrel in east-central Illinois I conducted a live-trapping survey during spring 1998. The survey focused on Champaign County, the Illinois county in which the largest number of specimens has been collected. Traps were placed at nine sites in Champaign County and three sites each in adjacent Vermilion and Piatt counties.

Eleven of the sites were located near historical records for this species. Two sites were in grasslands at Kennekuk County Park (Vermilion County); the others were along abandoned or active railroad lines. All sites had a dense cover of grass, forbs, and shrubs. Traps were baited with cracked corn, carrot, and sliced meat, and each site was trapped for three consecutive days. Only one Franklin's ground squirrel was captured during 1,032 trap-days, an adult male trapped along an abandoned railroad

Abandoned railroad right-of-way near Urbana, Illinois where a single Franklin's ground squirrel was captured.

embankment east of Urbana. This supports the perception that Franklin's ground squirrel has become rare in Illinois. It also demonstrates the importance of preserving or restoring vegetation along abandoned railroad corridors for wildlife habitat. Surveys in other parts of Illinois and additional habitats (perhaps interstate highway rights-of-way) would shed more light on the conservation needs of this prairie species.

Joyce E. Hofmann, Center for Biodiversity

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