Baseline survey of furbearing mammals within the South Fork drainage Sun River, Montana

Abstract

The relative abundance, distribution and habitat use of seven species of furbearing mammals and five additional species with fur or sport values were studied in the South Fork drainage of the Sun River, in north central Montana, from June through August of 1982 and January through June of 1983. Species investigated included: bobcat (Lynx rufus), Canadian lynx (Lynx canadensis), fisher (Martes pennanti), pine marten (Martes americana), wolverine (Gulp gulo), river otter (Lutjra canadensis), beaver (Castor canadensis),mountain lion, (Fells concolor), grizzly bear (Ursus arctos), black bear (Ursus americanus), coyote (Canis latrans) and wolf (Canis lupus). Small mammals were trapped at three locations during late summer 1982 to determine their availability and relative numbers during high prey population periods. A total of 94 small mammals were captured during 331 trap-nights resulting in a total efficiency of 28.4%. Approximately 1,207 km of transects within the 1,036 km2 study area were traversed during the 2 field seasons. A total of 4,154 incidences of sign were recorded from 10 landtypes within 6 subunits. Prey species (rodents, lagomorphs and grouse) contributed >80% of all sign encountered. Coyotes contributed 16% of all sign observed. There was was a significant positive correlation between coyotes and lagomorph signs for the different landtypes (r=0.864, p<0.05) and subunits (r=0.991, p<0.001). Signs from carnivorous species were positively correlated (p<0.001) with prey species for both landtypes (r=0.927 ) and subunits (r=0.990). Other species detected, which comprised 2% of all signs, included wolves, grizzly bears, black bears and mountain lions. Furbearer sign encountered consisted of 1 river otter, 5 lynx and 12 bobcats. Bear tracks encountered per transect kilometer traveled were 1/45 km and 1/13.4 km for grizzly and black bear, respectively. This number for grizzly bears is lower than reported in previous studies conducted in the vicinity. Trapping records show 14 bobcats, 4 lynx and 3 river otters have been harvested from the study area during the the 1977-1983 trapping seasons. Data from sign showed an apparent lack of pine marten, wolverine and fisher within the area. Pine marten were trapped in the area as recently as in the 1950’s. Wolverine observations have been reported from sites immediately adjacent to the study area.