Home ranges of European Ground Squirrels (Spermophilus citellus) in two habitats exposed to different degrees of human impact [Domovské okrsky sysla obecného (Spermophilus citellus) ve dvou biotopech s odlišnou intenzitou antropogenního vliv
Ilse E. Hoffmann, Eva Millesi, Michaela Brenner, Tabea A. Turrini
Because of habitat loss and alteration, European ground squirrel populations in Austria are increasingly restricted to isolated fragments, where, however, they can reach conspicuous densities. To investigate potential effects of habitat alteration and population density on space use, we radio-collared comparable numbers of individuals at two different study sites; a secondary steppe with relatively low anthropogenic influence and a highly altered, isolated alfalfa meadow. Subsequently, individual movements were recorded during approximately one week. Home ranges were compared between the two study sites and sex and age differences were examined. Juveniles covered larger areas in the secondary steppe, where population density was relatively low. In ≥1year-old individuals, mean home ranges did not differ between the two habitats, although they exhibited high individual variation in the secondary steppe. In either of the study sites, no sex difference in home-range size was found. In addition, minimal and maximal distances moved were calculated. One yearling male with scrotal testes in the secondary steppe dispersed from its original home range, moving about 750 m. We conclude that habitat characteristics affect space use in juvenile individuals. Since juveniles are the ones benefiting most from selective foraging to promote growth and fattening, quality and distribution of food resources probably accounted for differences in home-range size in the two study sites. Furthermore, variances in population density and predator presence could have contributed to the observed movement patterns.