Post-dispersal sugar maple (Acer saccharum) seed predation by sciurids and other small mammals in a northern hardwood forest

Small granivorous mammals can potentially affect forest regeneration through seed dispersal or predation. Using live-trapping efforts and track boards with tagged sugar maple (Acer saccharum) seeds in June and August of 2006 at eight mixed forest sites in Michigan's Upper Peninsula, we asked: (1) are sugar maple seeds provided later in the summer more often cached? (2) Are small mammals seed dispersers or predators at these sites? (3) How did seed predator (i.e., all granivorous small mammals) and sciurid (chipmunks and squirrels only) biomasses affect the proportion of seeds eaten? (4) How did habitat structure affect small mammal biomasses? 5) How did sciurid biomass relate to non-sciurid biomass? Although fewer seeds were cached in August, we found that small mammals, eastern chipmunks in particular, were predators of sugar maple seeds, with an increased proportion of seeds eaten with increasing seed predator and sciurid biomasses. We also found a larger seed predator biomass and the presence of eastern chipmunks in areas with relatively more deciduous trees, and sciurid biomass increased with non-sciurid biomass, indicating their similar responses to environmental resources. Future studies should track sugar maples seed fates and eastern chipmunk biomass changes throughout the year to locate the time of highest seed survival.