Individual behaviour shapes patterns of bird‐mediated seed dispersal

Abstract

Abstract Seed dispersal is a key component in a plant's life cycle, allowing the colonization of new habitat and eventually enabling range shifts. For animal‐dispersed plants, the behaviour of seed‐dispersing animals has direct consequences for the fate of a seed. However, there is little empirical evidence on how individual behaviour of animals affects seed dispersal. Here we investigated the effects of individual behaviour on seed dispersal distance and location by analysing movement data of spotted nutcrackers (Nucifraga caryocatactes) during harvest and scatter‐hoarding of Swiss stone pine (Pinus cembra) seeds. To assess individual variation in seed dispersal patterns, we compared daytime hourly displacement patterns across individuals. We further identified seed caching locations of individual birds and analysed their potential for pine regeneration. We found that nutcrackers showed one of two distinct behaviours: short‐distance seed dispersal and long‐distance seed dispersal. The caching locations resulting from the two behaviours differed markedly in the regeneration potential of Swiss stone pine: seeds transported over short distances were cached at high elevations with high regeneration potential within the pine's current habitat, while seeds transported over long distances were cached at low elevations with low regeneration potential outside of the pine's habitat. The behaviours were not associated with bird body mass, relative wing length or sex. Our results emphasize that intraspecific individual behaviours of seed‐dispersing animals can have far‐reaching consequences for ecosystem functions. As a major determinant of seed dispersal dynamics, individual behaviour should be taken into account for a better understanding of ecosystem functions under current and future environmental conditions. Read the free Plain Language Summary for this article on the Journal blog.