Northern Prairie Wildlife Research Center
Habitat and History. Badgers in the prairie pothole region are near the northern edge of their geographic range (Hall 1981). They are adapted to northern grasslands and seemingly were abundant throughout the region at the time of settlement (Bailey 1926; Seton 1953; Bird 1961). Badgers have remained widely distributed throughout the region, but populations probably declined substantially after settlement and have remained low in most areas since that time (N. Criddle 1929; Soper 1946,1961; Bird 1961; Baines 1969; Banfield 1974; Jones et al. 1983).
The badger has not benefitted from human presence. It was intensively trapped for fur during the early 1900's and populations throughout the prairie pothole region were greatly reduced (Bailey 1926; Bird 1930; Drescher 1974; Jones et al. 1983). Moreover, it was often killed directly by humans because it dug unwanted holes and indirectly by collisions with vehicles (Messick et al. 1981). The reproductive potential of badgers is low (Messick 1987); hence, population levels are easily reduced by high mortality. Habitat changes in the region have also harmed this species. Badgers are fossorial and feed extensively on small rodents, especially ground squirrels (Spermophilus spp.) and pocket gophers (Geomys bursarius, Thomomys talpoides; Salt 1976; Messick and Hornocker 1981; Jones et al. 1983). Extensive conversion of grassland to cropland greatly reduced the availability of this prey. Badgers are particularly noticeable because of their digging, but finding identifiable tracks in areas with low badger populations is often difficult.
Population Structure. Adult badgers are solitary although home ranges of individuals may overlap considerably (Messick 1987). Home range sizes of adults averaged 1.6 and 2.4 km2 for females and males in Idaho (Messick and Hornocker 1981) and ranged from 1.4 to 6.3 km2 in Utah (Lindzey 1978). Home ranges of two radio-tracked females in Minnesota were 8.5 and 17.0 km2 (Sargeant and Warner 1972; Lampe and Sovada 1981). The latter home ranges are probably more typical of badgers in the prairie pothole region.
Distribution and Abundance. Badgers were present in all study areas except two (Hay Lakes, Hitterdal), but populations were low in most areas (Fig. 10). In general, badgers were most numerous along the southwestern edge of the region (where grassland is most abundant [Table 1]) and least numerous in the aspen parkland and in the most intensively farmed study areas (Fig. 10). The percentage of study areas in which badgers were common or more abundant was greater in the prairie than in the aspen parkland (Appendix Table 7); the difference was greatest of all surveyed carnivores. In Canada, badgers were common in 6 study areas (38%) and uncommon or less abundant in 10 (63%). In the United States, they were numerous in two study areas (12%), common in eight (47%), and uncommon or less abundant in seven (41%). In seven study areas, tracks of badgers were found in 1-3 quarter sections in a year, indicating intermittent presence of only one or two badgers in each area (Appendix Table 5). The removal of one adult badger from one study area (Fredonia) in 1987 and one from another (Lake Park) in 1988 (Appendix Table 3) probably lowered the index of badger tracks for those two study areas. The two adult badgers removed from one study area (Fredonia) in 1988 were caught after the track surveys were completed. The removal of only four adult badgers from the three areas from which predators were removed during 6 study area-years further suggested that populations were low.
Fig. 10. Percentage of searched quarter sections (in black) by study area in which badger tracks were found or in which the abundance of tracks was estimated during two systematic annual searches in April-June in >= 1 study year (Appendix Table 5) and ratings of the abundance of badgers in each area, 1983-1988. Results for the study areas searched >1 year were averaged; study areas are in the prairie pothole region.