Can You Teach an Old Parrot New Tricks? Individual Variation in the Problem-Solving Abilities of Wild Kaka (Nestor Meridionalis)
Identifying factors that may influence cognitive variation in the wild is essential for furthering our understanding of how ecological and evolutionary mechanisms shape cognitive phenotypes. Yet, studies on cognitive variation in the wild and its causes and consequences are still rare. In both the wild and captivity, birds have become a centre of attention, revealing striking cognitive abilities that may rival the great apes. While much of this research has focused on corvids, few parrot species have been studied thoroughly. One of these species is the kea (Nestor notabilis), which has shown remarkable social and physical cognitive skills, including the use of tools. This thesis explores the innovative problem-solving skills of the only other Nestor species, the kaka (Nestor meridionalis), with the overall aim to investigate ecological, developmental and genetic factors influencing within-species variation of these abilities in the wild. When confronted with a series of novel problems at a familiar feeding station, juvenile kaka outperform adult kaka, especially in their ability and efficiency to find an innovative solution to acquiring the food reward. This is particularly the case when modification of a pre-learned behavioural response is required and is further expressed in the juveniles’ higher individual persistence and exploration diversity, which suggests they may be more behaviourally flexible. Testing for this hypothesis using a Multi-Access-Box approach confirmed faster, more flexible discovery of alternative solving strategies in younger birds. Further analysis of the kaka’s innovation abilities uncovered potential genetic effects on solving ability as shown by full sibling comparison. This provides first potential evidence for heritability of a cognitive trait in the wild and thus presents an important step for furthering our understanding of how natural selection may act on cognitive traits. Between-species comparison of kaka and kea in the physical and social cognitive domains reveals striking similarities. This suggests that the differences in the life histories of these two species play a secondary role in the evolution of Nestor parrot cognitive abilities, which may instead be retained from their common ancestor.