Importance of Nonbrowse Foods to Moose on the Kenai Peninsula, Alaska

Abstract

Food intake of three tame moose (Alces alces) was observed on the Kenai Peninsula, Alaska during summer on normal range and during winter and spring on normal and depleted range. Plant species and bite sizes were recorded for 49,308 bites consumed. Food eaten varied between summer and winter, and moose ate a greater variety of forage than previously realized. Birch (Betula papyrifera) leaves comprised 56 percent (by number of bites) of the summer diet, forbs 25 percent, grasses, sedges and aquatics 10 percent, and willow (Salix spp.) 5 percent. Winter diet on range that had supported average moose densities for the area (15 per square mile) was 72 percent birch twigs, 21 percent lowbush cranberry (Vaccinium vitis-idaea) and 6 percent willow and alder (Alnus crispa). On depleted winter range, stocked for 18 months with abnormally high moose densities, birch twigs comprised only 22 percent of the diet. The bulk of bites taken were of lowbush cranberry (51 percent) and foliose lichens (Peltigera spp.) (23 percent). In May, moose consumed 10-30 times as much cranberry and lichen as birch. Availability of understory forage species during part of the winter is probably an important factor in supporting the very high moose densities found on this range. J. WILDL. MANAGE. 37(3):279-287 Analyses of moose range commonly stress abundance, production, and use of large woody shrubs (Aldous and Krefting 1946, Krefting 1951, Spencer and Chatelain 1953, Spencer and Hakala 1964, Houston 1968). This emphasis occurs because browse is the only food available to moose in winter over much of their range and winter range is classically considered a limiting factor for moose populations, and because range survey methods depend on the ease by which one can visually estimate browse conditions (Cole 1963). Emphasis on woody shrubs has persisted despite an impressive array of evidence that moose are extremely catholic in their tastes. Especially in spring and summer, they consume forbs, grasses, mushrooms, lichens, and practically all other floral components of their environment. Murie (1934) reported a great variety of foods taken on Isle Royale. Peterson (1955) listed more than 100 species and groups of plants taken at least occasionally by moose. Houston (1968), although stressing that browse was the most important food class during all seasons in Wyoming, demonstrated that moose ate significant quantities of grasses, sedges, rushes, and forbs in spring and