Intraspecific variation in the foraging ecology of kea, the world’s only mountain- and rainforest-dwelling parrot

Intraspecific variation can have important knock-on effects on population dynamics and ecosystem processes. There are good indicators that intraspecific differences may exist in the foraging ecology of kea parrots (Nestor notabilis). Kea breed in two markedly different habitats (alpine and temperate rainforest), and have pronounced sexual size dimorphism of their upper bill, which may indicate niche partitioning between the sexes. Additionally, as a long-lived species, they can potentially acquire a vast amount of information regarding food sources within their environment, suggesting variation between age classes. We used field observations and faecal analysis to investigate the foraging ecology of kea. We found evidence of invertebrate foraging significantly more frequently in temperate rainforest than in alpine regions, where kea foraged more frequently on fruit. In the alpine habitat, kea fed mainly on fruit during summer and autumn, changing primarily to leaves during winter and spring and increasing invertebrate consumption in springtime. Although there was no discernible impact of sex, we found that adult males foraged more on roots and invertebrates than immature kea, possibly because they were able to exploit a more varied diet through experience. Future research should investigate the relationship between invertebrate foraging and breeding ecology in kea.