Redosier dogwood seeds are primarily dispersed by birds and mammals. Animal dispersal likely facilitated establishment of redosier dogwood on a landfill reclamation site on Staten Island, New York. Redosier dogwood established naturally within 1 year of reclamation, and the nearest redosier dogwood seed source was 705 feet (215 m) from the site .
Many bird species eat redosier dogwood fruits and likely disperse its seed. In New England, redosier dogwood occurred in the diets of 95 bird species (review ). In laboratory experiments, viability of redosier dogwood seeds was largely unaffected after consumption by pheasants. More seeds collected from pheasant feces germinated (29%) than seeds that were dried and stored in the laboratory (22%). Stratification increased germination of redosier dogwood seeds collected from pheasant feces .
Redosier dogwood seeds were not harmed by consumption by bears, and seeds in bear feces may present an opportunity for secondary dispersal by rodents. In northeastern Minnesota, germination of redosier dogwood was better for redosier dogwood seeds collected from black bear feces (18%) than for unconsumed fresh seeds (7%) (P<0.05). When fresh seeds and seeds collected from bear scat were refrigerated for 50 days before testing, germination of seeds from feces was 22% and for unconsumed seeds was 3% (P<0.01) . In field experiments, researchers found that rodents may be important in the secondary dispersal of redosier dogwood seeds from bear and bird feces, but that secondary dispersal varied among years. Emergence was poorest when redosier dogwood seeds were left in bear feces and was 4 times more likely when seeds were removed from bear feces and planted 5 mm deep. Researchers suggested that unconsumed seeds in deer mice caches would have a better chance of establishing than seeds remaining in bear scat .
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