Seasonal and sexual differences in American marten diet in northeastern Oregon
Information on the diet of the American marten (Martes americana) is vital to understanding habitat requirements of populations of this species. In a study carried out from January 1994 to October 1997 in coniferous forest in the Blue Mountains of Oregon (USA), the frequency of occurrence of prey items found in 1014 scat samples associated with 31 radiocollared American martens included 62.7% vole-sized prey, 28.2% squirrel-sized prey, 22.4% insects, 19.5% birds, 13.3% plant material, and 2.4% lagomorphs. A significantly higher proportion of voles (Microtus spp.), southern red-backed voles (Clethrionomys gapperi), and chipmunks (Tamias spp.) were found in the summer diet than the winter diet, and a higher proportion of northern flying squirrels (Glaucomys sabrinus), unidentified squirrels, bushy-tailed woodrats (Neotoma cinerea), and mountain cottontails (Sylvilagus nuttallii) were found in the winter diet than the summer diet. Insects and plant remains represented a higher proportion of the diet in summer than winter. Females preyed on a higher proportion of shrews (Sorex spp.) and chipmunks, while males preyed on a higher proportion of southern red-backed voles.