Patterns of frugivory, seed dispersal and predation of blue fan palms (Brahea armata) in oases of northern Baja California

Variations in spatial and temporal availability of fruits and seeds in oases are important not only for animal seeking resources, but also for palm population dynamics. We explored spatial association patterns between avian frugivores and blue fan palms in two natural palm patches of Baja California. Spatial patterns were analyzed at the individual tree and at 2 ha patches. We evaluated seed predation by vertebrates and invertebrates, and vertebrate seed dispersal around palms. Birds responded to fruit aggregation at the individual tree and the patch scales, but responses varied between patches. Palm fruit variables—the quantity and the phenological phase—and avian visits showed strong spatial aggregation and association at both scales in one patch, but not in the other. The intensities of seed predation and seed dispersal were significantly higher directly below palms than at >3 m away from them. Patches differed in the intensity of seed predation around palms and in the diversity of mammalian dispersers, but not in the intensity of seed dispersal. Blue fan palms function as important resources' focuses for a great number of animals that use palm oases as corridors, bringing seeds as they move and connecting isolated populations of palms.