Enders, M. S. and S. B. Vander Wall. Black bears are effective dispersers of seeds, with a little help from their friends. Oikos 121:589-596.

See a related study: Vander Wall, S. B., K. M. Kuhn, and J. Gworek. 2005. Two phase seed dispersal: linking the effects of frugivorous birds and seed-caching rodents. Oecologia 145:282-287.

Mark Enders

Jake Dittel

Mark Enders preparing a artificial bird feces
to test whether rodents removed seeds from
bird feces.

My research investigated diplochory or two-phased seed dispersal. Large carnivores like black bears eat a lot of fruit and pass the seeds intact in their feces. However, feces are not a very good place for seedlings to establish because they are very crowded and the feces dries out quickly. But some species of rodents, like deer mice (Peromyscus maniculatus), will remove the seeds as a food resource. They store many of these seeds in soil and if they don't return to eat them later, they can germinate. This combined form of dispersal if far more effective than either species by itself, because bears can carry the seeds long distances and deer mice can scatter the seeds and bury them in soil where the chance of seedling establishment if far greater.

Bear feces can contain thousands of seeds, in the case those of dogwood, Cornus stolonifera.

A different artificial feces after deer mice had visited during the night and removed most of the seeds. 

Artificial feces with 50 chokecherry seeds (Prunus virginiana) seeds on its surface.

Three deer mice removing seeds from bear feces.