Rapid sequestration and recaching by a scatter-hoarding rodent (Sciurotamias davidianus)

Many seed-hoarding species are faced with ephemeral pulses of seeds that result in competition at seed sources and the need to minimize hoarding time during the limited time seeds are available. Here we tested the hypothesis that a seed-hoarding species (Pere David's rock squirrel [Sciurotamias davidianus]) rapidly scatter hoards seeds near seed sources to maximize harvest rate, and then subsequently recaches seeds to further reduce cache losses. We tracked the caches of wild walnut (Juglans mandshurica) scatter hoarded by S. davidianus, the exclusive dispersal agent of this highly preferred nut species. We followed dispersed nuts in both the field and in a large enclosure in a manner that allowed us to follow patterns of recaching through the scatter-hoarding process. In the field, S. davidianus initially cached close to nut sources and then subsequently recached nuts on multiple occasions progressively farther from sources, always in the same direction, at lower densities, and at sites with more vegetative cover (e.g., under shrubs). In enclosures, each of 6 squirrels first cached nuts closer to the nut source on the 1st day of observation, and then subsequently recached nuts closer to the nest, sometimes at decreasing densities. We suggest that, in addition to pilferage risk, cache spacing by S. davidianus may be influenced by the potential for competition at the seed source and proximity to the burrow or the core of the home range, and that caches might be managed to accommodate all of these factors. Future studies should consider how such recaching behavior influences patterns of cache recovery, the ultimate distribution of dispersed nuts, and seed fates.