The role of wild canids in the seed dispersal of Washingtonia robusta (Arecaceae) in Sonoran Desert oases

The canids gray fox Urocyon cinereoargenteus and coyote Canis latrans consume the fruits of Mexican fan palm, Washingtonia robusta, endemic to the oases of the Sonoran Desert. We analyzed biotic covariates (consumption, dispersal, and germination of palm seeds and abundance of gray foxes and coyotes) and organic matter in soils between different exposures in Barajitas Canyon, to better understand palm establishment. Mexican fan palm seeds found in feces had a greater germination rate (94%) than those dispersed directly from mother plants (55%). According to the results for palm establishment, the habitat can provide likely locations for successful colonization that did not significantly differ among sampling sites (α = 0.05, F = 1.104). The canyon is a dynamic habitat in which the reproductive season of these 2 mammals coincides with palm reproductive phenology. Our data suggest that the consumption and dispersal of W. robusta seeds by gray fox and coyote represent a positive interaction that plays a significant role in the establishment of this oasis species.