Fitness consequences of hoarding behaviour in the Eurasian red squirrel

Hoarding increases food availability during periods of scarcity, and therefore should enhance fitness. Although short-term advantages of hoarding have been described for birds, effects over an animal's lifetime have not yet been documented. Here, we report that in the red squirrel, Sciurus vulgaris, individuals which recovered many cached tree seeds increased their body mass and were more likely to survive the spring breeding season than those that recovered fewer seeds. There was no significant effect of the time spent recovering cached food on the probability for females to produce a spring litter. In the long-term, hoarding behaviour was related to fitness in two ways; (i) squirrels spending more time recovering hoards survived longer; and (ii) females with a high recovery activity tended to wean more young in their lifetime than those that spent less time recovering hoards. Our data indicate that in red squirrels, food hoarding is an adaptive foraging strategy to preserve temporarily abundant food resources for future periods of hardship, and that individuals that hoard and recovery many tree seeds are more likely to survive and reproduce.