Space use and habitat selection of long-tailed weasels ( Mustela frenata) in southern Illinois

Long-tailed weasels have large home ranges relative to their small body size. Some studies suggest that home-range size of long-tailed weasels is related to prey availability. Space use of long-tailed weasels is similar to that of other small mustelids. Home-range size of weasels can vary greatly and home ranges of males are larger than those of females. I livetrapped long-tailed weasels in Pyramid State Park, Perry County, Illinois and fit each weasel with a radio-collar. I calculated home ranges and core areas for 7 male weasels and 1 female weasel. Average home-range and core-area sizes for males were 28.0 ha (SE = 9.0, range = 2.2 -- 68.8) and 5.9 ha (SE = 1.7, range = 0.3 -- 11.3), respectively. Home range and core area sizes for the 1 female weasel were 18.3 ha and 2.8 ha (n = 15), respectively. I also recalculated home ranges from Richter (2005) for comparison. Average home-range and core-area sizes for 4 males from Richter (2005) were 49.6 ha (SE = 26.5, range = 0.2 -- 109.8) and 10.8 ha (SE = 5.7, range = 0.02 -- 21.5), respectively. Average home-range and core-area sizes for 4 females from Richter (2005) were 21.6 ha (SE = 9.6, range = 6.2 -- 47.4) and 5.6 ha (SE = 2.8, range = 1.2 -- 12.9), respectively. Two weasels in my study had primary den sites (residents) and small home ranges (2.2 -- 5.3 ha) compared to weasels that did not use primary den sites (roamers). The maximum distance moved in 48 hours ranged from 450 m -- 2400 m and was similar between residents and roamers. The results of this study and other studies indicate that long-tailed weasels have great variation in home range sizes which has also been documented in other mustelids. Long-tailed weasels also have a dichotomy in space use, some are residents and some are roamers.;Long-tailed weasels are both predators and prey, so habitat selection could reflect the competing needs to find prey and seek cover from predation. I quantified habitat classes within the study area and used compositional analysis to test the prediction that weasels select habitats that offer high prey abundances (reed grass, grassland, and shrubland) and high protection from predators (reed grass and shrubland). Reed grass was preferred above all other habitat types. Reed grass offers high seasonal abundance of red-winged black birds, prey for long-tailed weasels, and also offers year round cover from predation. Agriculture was the least preferred habitat type. These results lend support to the prediction that weasels will select habitats that offer high prey abundances and high protection from predators.