Ground-feeding migratory songbirds as cellular slime mold distribution vectors.

Cosmopolitan species of cellular slime molds occur continents apart in both tropical and temperate zones of the world though the spore masses are too heavy to be wind borne, and water dispersal is limited to the watercourses. A highly mobile distribution vector was found in ground-feeding migratory song birds. Nine ubiquitous species and 2 ecologicially distinct species of dictyostelid cellular slime molds were isolated from the feces of ground-feeding eastern North American migratory thrushes, finches, sparrows and warblers, both on breeding and winter grounds. Three propagules of slime molds, amoebae, spores and macrocysts survive passage through the avian digesive tract and remain in the gut long enough to be transported by major bird migrations. Habitats with the greates species diversity of both cellular slime molds and ground-feeding passerines concur in both eastern North America and Central America. Birds actively seek their prefered habitats; the cellular slime molds have arrived at these habitats as passengers. Rare slime molds can serve as a marker to the habitats that migratory birds have visited, or birds with known habitats can provide clues as to the distribution of rare species of cellular slime molds.