Summer Habitat Preferences and Activity Patterns of River Otters In Grand Teton National Park

Abstract

I studied the natural history of river otters. (Lontra canadensis) during the summers of 1982-1986 and 1995-1997 in Grand Teton National Park, Wyoming. Habitat preferences were analyzed by tallying sightings on 5 types of habitat along 16 km of the Snake River. Otters were seen on all 5 habitat types and exhibited a strong preference for the logjam/beaver lodge category. Beavers and otters sometimes occupied a lodge simultaneously. I recorded daytime activity directly in 1982 and noted a large peak in mid-morning and a small one in late afternoon. To obtain information indirectly on round-the-clock activity I employed 6 modified camera monitors activated by treadle-switches at frequently used sites. Pooled records for 3 summers showed almost two and a half times higher activity by day than by night, a finding opposite of what was expected. The hypothesis I suggest is that diurnal activity exceeds nocturnal activity because of the habituation of otters to humans over a half century's tradition of frequent exposure and non-harassment in the national park. In the summers of 1982-1986 and 1995-1997 I made a study of the natural history of river otters (Lontra canadensis), in Grand Teton National Park under auspices of the University of Wyoming - National Park Service Research Center. Occasional observations were made along the Snake River from Flagg Ranch near the north boundary of the park to the north end of Jackson Lake and from Pacific Creek to Deadman's Bar. However, the 3 km stretch of river from just below Jackson Lake Dam to the Oxbow was the site of most intensive study. (See Fig. 1)