Sexual differences in food re‐caching by New Zealand robins Petroica australis

Abstract

We presented monogamous pairs of New Zealand robins Petroica australis with a superabundant supply of artificial prey and then observed birds re‐cache previously hoarded prey. Males and females frequently relocated and redistributed previously hoarded prey. Both sexes also re‐cached prey that was originally hoarded by their mate. However, re‐caching rates of retrieved and pilfered prey differed between sexes. Female‐made caches were re‐cached at the same rate by both females and pilfering males, while male‐made caches were re‐cached more frequently by pilfering females. The re‐caching of previously hoarded prey is consistent with the hypothesis that re‐caching reduces theft. However, re‐caching pilfered prey suggests that it might also play a role in cache theft strategies. Higher rates of re‐caching by pilfering females cannot be explained by current hypotheses used to account avian re‐caching behaviours. We suggest two new hypotheses, sexual dimorphism in spatial memory and indirect mate provisioning, which may help to explain the evolution of re‐caching in New Zealand robins.