Niche overlap between sympatric coyotes and bobcats in highland zones of O lympic M ountains, W ashington

The 20th century extensive range expansion of coyote C anis latrans throughout N orth A merica may impose negative effects on native carnivores. We investigated the interspecific niche relationships to assess potential for competition between sympatric coyote and a similar‐sized felid – bobcat L ynx rufus – throughout the highland zones (elevation >1000 m) of O lympic N ational P ark, O lympic P eninsula, W ashington. Through systematic collection and analyses of scats for both carnivores ( M ay– S eptember 2005–2006), we determined food habits (composition, diversity, overlap of diets) and habitat use patterns. To ensure correct determination of carnivore species, we used mtDNA analysis of scats. Scat analysis indicated extensive dietary overlap between coyote and bobcat ( P ianka's overlap index = 0.97). For both carnivores medium‐sized mammals comprised the predominant prey: mountain beaver A plodontia rufa and snowshoe hare L epus americanus ; each occurring in about 50% of the scats. High dietary similarity indicated the potential for interspecific exploitative competition for mammalian prey, especially in harsh climatic conditions of high mountains. However, observed patterns of habitat selection inferred from scat distribution showed differences between coyotes and bobcats, implying some degree of habitat partitioning. Bobcats preferred relatively dense montane forests (canopy cover >40%) at lower elevations, and avoided the alpine zone, while coyotes inhabited mainly alpine and subalpine zones and mostly avoided forest. We conclude that observed habitat separation may alleviate foraging competition between coyote and bobcat. Whether this habitat separation will decrease potential negative effects of coyote colonization on bobcat abundance, or whether it indicates ongoing displacement of bobcats by coyotes, remains an open question.