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The play behaviour of the critically endangered kakapo (Strigops habroptilus; Aves: Psittaciformes: Psittacidae) is here compared to that of its closest relatives, the kea (Nestor notabilis) and the kaka (Nestor meridionalis). Contrasting kakapos, which are relatively solitary, with the more social Nestor parrots provides an attractive test of the relative contributions of phylogeny and sociality to the evolution of play. Overlapping cluster analysis of play sequences using a hypergeometric similarity metric indicated that kakapo play is generally less complex, lacking the intensity, duration, structure, and reciprocity of play in the Nestor parrots. Kakapos have a later age of first reproduction than the comparison species, but they lack the well-developed social interactions between post-fledging young and adults that are characteristic of keas and kakas. Social play in parrots appears to be most readily predicted from their patterns of social development, emerging within a constellation of behaviours associated with independent young that remain in the vicinity of adult groups. [ABSTRACT FROM AUTHOR]

Regional and ontogenetic variation in the contact calls of the kea ( Nestor notabilis), an omnivorous and socially complex New Zealand parrot, were examined throughout the range of the species. We recorded samples of kee-ah contact calls from sixteen resident adults and eleven juveniles and demonstrated significant differences between age classes in the acoustic form of the vocalization. Canonical correlation analysis revealed a gradient in the form of the kee-ah call in both adults and juveniles along and across the escarpment of the Southern Alps, the primary longitudinal mountain range on the South Island of New Zealand. Although the juvenile call varies geographically along the same axes as the adult version, the aspects of the call that vary geographically are strikingly different, suggesting that the variation results from independent processes of vocal learning in the two age classes. A similar analysis of squeal vocalizations, which are only produced by juveniles, found even greater levels of geographic variation. We suggest that the immediate social environment may serve as the primary factor shaping the vocal patterns of both juveniles and adults, producing localized homogeneity in call form within each age class. [ABSTRACT FROM AUTHOR]

Social play in the kaka (Nestor meridionalis), a New Zealand parrot, is described and contrasted with that of its closest relative, the kea (Nestor notabilis), in one of the first comparative studies of social play in closely related birds. Most play action patterns were clearly homologous in these two species, though some contrasts in the form of specific play behaviors, such as kicking or biting, could be attributed to morphological differences. Social play in kakas is briefer, more predictable, and less sequentially diverse than that shown by keas. Kaka play also appears to be restricted to fledglings and juveniles, while the behavior is more broadly distributed among age groups in keas. Play initiation behaviors were relatively more frequent in kakas and more tightly intercorrelated in occurrence. A primary grouping of action patterns in kakas consisted of arboreal play, which was rare in keas. The most striking species difference was exhibited in social object play, which is pervasive among keas, but which was not observed in kakas. Although the two species are morphologically similar, they differ strikingly in several aspects of their ecology and social behavior, including the duration of the association between juveniles and adults, the degree of exploratory behavior, and the flexibility of their foraging strategies. The observed species differences in play behavior are discussed in relation to the contrasting life histories in the two species, suggesting that many features of social play may reflect evolutionary responses to particular ontogenetic and ecological constraints. [ABSTRACT FROM AUTHOR]

Although social play is broadly distributed among mammals, it is infrequently encountered in other vertebrate taxa. It is, however, displayed in a fully realized and complex form in several groups of birds. Unambiguous accounts of social play have been recorded from thirteen species of parrots, seven species of corvids, and several hornbills and Eurasian babblers. We conducted an analysis of the avian play literature, testing for differences between avian taxa, as well as for correlations between play complexity, brain size, and age of first reproduction. Corvids were far more likely to show social object play than parrots. Corvids, parrots, and hornbills had larger relative brain sizes than would be predicted from a class-level allometric regression, but brain size was not associated with the complexity of social play among genera within taxa. Play complexity within parrots and corvids was, however, significantly associated with the age of first reproduction. The likelihood of complex social play appears to increase when delayed reproduction is accompanied by persisting relationships between adults and post-fledging juveniles. The adaptive significance of social play in birds thus offers intriguing parallels to similar analyses in mammals. [ABSTRACT FROM AUTHOR]