Presence of conspecifics, time of day and age affect willow tit food hoarding

Abstract

Willow tits,Parus montanus, spend the winter in flocks and hoard food especially in the autumn to be used later. For caching to be an evolutionarily stable strategy, the hoarder should be more likely to retrieve its caches than conspecifics. The effects of individual differences, the time of day and, especially, the presence of conspecifics and heterospecific birds on caching behaviour of free-living willow tits were examined with a logit model. The presence of conspecifics had the strongest influence on caching: if there were other willow tits near the observed individual, it was less likely to cache. Willow tits stored food at a greater intensity in the morning than in the afternoon. Yearlings stored more intensively than adults. Individuals differed in their caching intensities. However, there were no significant interactions between the factors investigated, indicating, for example, that individual birds responded similarly to the factors studied. The presence of hetero-specific Paridae or non-Paridae had no effect on the caching rate in the willow tit. It is possible that conspecifics are perceived as potential kleptoparasites (immediate threat) or pilferers (long-term threat) and therefore avoided when hoarding.