An evaluation of a mammalian predator, Martes americana, as a disperser of seeds

Effective animal dispersers of fruit seeds have been primarily considered to be herbivorous birds and bats. To evaluate the seed-dispersal efficacy of a mammalian predator, we studied the American marten (Martes americana) as a disperser of two blueberries (Vaccinium alaskaense, V. ovalifolium) and salmonberry (Rubus spectabilis) on Chichagof Island, Alaska, by combining data on movement speed and gut-passage speed. Martens traveled a median distance of 133 m in 0-1 h and 501 m in 4-5 h. Median gut-passage time for V. alaskaense was 4.1 h and for R. spectabilis was 4.6 h. Median dispersal distances for both berry species were estimated to be about 500 m. In old-growth stands, V. ovalifolium seeds cleansed of pulp did not germinate differently than seeds cleansed of feces, suggesting that the marten gut does not harm germination. Vaccinium spp. seeds germinated better if cleansed of feces than if inside intact berries, indicating that passage through the gut of a marten improves germination over fruit fall alone. For V. alaskaense in old growth, seeds cleansed of feces germinated less than seeds cleansed of pulp, but still had high (41%) germination rates. We conclude that American martens move ingested seeds long distances, some of the highest reported for a mammal. This efficacy is in part due to the predatory adaptations of martens. Predators may have heretofore unrecognized value in shaping landscape patterns of berry-producing plants.