Papers in the Biological Sciences


Date of this Version



Published in Behaviour 142 (2005), pp. 1-20. Copyright © 2005 Koninklijke Brill NV, Leiden. Used by permission.


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.