Status and ecology of Franklinís ground squirrel (Spermophilus franklinii)

in Illinois






Franklinís ground squirrel (Spermophilus franklinii) appears to be declining in the eastern portion of its range, but current data on its status in Illinois are lacking.In 2001, I conducted a mail survey of 166 wildlife professionals from throughout the historical range of the species in Illinois to obtain information pertaining to extant and extirpated populations, and local population trends.The majority of the survey recipients did not feel that they were sufficiently familiar with the species to assess the status of S. franklinii.Twenty-six sites were chosen for livetrapping surveys to confirm the presence or absence of the species.I considered it likely that Franklinís ground squirrels persisted in these sites due to information provided in the mail survey and/or known historical occupancy.Trapping revealed that S. franklinii inhabited only 3 of the 26 trapping sites.I also located two other areas of probable occurrence in addition to the locations that I surveyed.While it is clear that Franklinís ground squirrel has declined in Illinois, the magnitude of this decline remains unknown due to the secretive behavior of the species and a lack of knowledge about its ecology.

During spring 2002, I live-trapped a small, apparently isolated, population of Franklinís ground squirrels in a 12-ha tallgrass prairie restoration (Barnhart Grove Prairie) located south of Urbana, Illinois.During the period following emergence from hibernation males used larger areas than females, and areas used by males overlapped to a high degree.Burrow systems were located most often in areas of cool season grasses with well-drained and moderately well-drained soils.Burrow systems also were often associated with trees, trash heaps, and buildings, all of which may offer some degree of protection from predators, conspecifics, and weather.Fourteen juvenile Franklinís ground squirrels (7 males and 7 females) were radio-tracked throughout dispersal to determine how far dispersers traveled, the timing of dispersal, if dispersal distance differed between sexes, and if the agricultural matrix surrounding the study site was a barrier.Males dispersed farther than females, but individuals of both sexes were located ≥ 1.5 km away from the study site.The farthest movement recorded was by a male who traveled 3.6 km.Dispersal was age-dependent for both sexes, occurring when individuals were 7-9 weeks old.Agricultural fields did not seem to hinder movement, probably because dispersal occurred before row crops were harvested and therefore still provided protective cover; however, open areas, such as roadways, may be barriers to some individuals.