Ignorant seed predators and factors affecting the seed survival of a tropical palm

In addition to acting as seed predators. some terrestrial mammals bury seed s via scatter hoarding. This study system used two permanent plots in exami ning the interaction between small rodents and the seeds of the palm Astroc aryum mexicanum. We tested how experimental burial, and fruiting status of the parent, distance to the parent, seed size, and microsite characteristic s affect the survival of these seeds. Up to 34% of the buried seeds that we re exposed only to ignorant rodent foragers (individuals not responsible fo r burial) survived. In comparison. less than 1% of seeds buried by scatter hoarding rodents survived in previous studies, a percentage that is compara ble to the low survival of unburied seeds in this study (<2%). Although unb uried seeds had very low survival, increasing distance and/or seed density positively affected survival of unburied seeds. Distance to parent had no e ffect on buried seed survival. Buried seed survival was most strongly and significantly determined by the fruiting status of the trees under which they occurred. Seeds experienced s ignificantly greater predation if buried under "parent" trees that fruited during the experiment. Buried seed survival was also negatively affected by germination, as germination may signal the presence of a seed to foraging rodents. There was some indication of a positive effect of tree density on seed survival between the two plots, whereas differences in rodent abundanc e appear to have no effect on seed survival. Seed size and microsite charac teristics had no significant effect on buried seed survival, likely due to the greater proportional effects of other factors and the longevity of A. m exicanum seeds. The results of this study were used to generate a hypotheti cal causal network showing how comparatively low recovery of buried seeds b y ignorant foragers combined with processes determining the removal of scat ter hoarding foragers from their scattered seed caches may affect seedling recruitment in A. mexicanum.