Jennifer Colvin

Cortopassi and Bradbury (2006) studied the differing contact calls of Aratinga canicularis (Orange-Fronted Parakeets) to determine the amount and usage of dominant calls produced[1]. Cortopassi and Bradbury studied non-breeding, mated Orange-Fronted Parakeets in captivity and in their natural habitat as well as free-living, breeding Orange-Fronted Parakeets to address whether contact calls by this species function to provide individual or pair identification. They used visual inspection, cross-correlation, and ordination of spectrograms to determine the diversity, richness, and eveness of each pair’s vocalizations (and to determine the dominant calls used). They found that the captive, non-breeding pairs had the least amount of diversity in their dominant contact calls used, while the free-living, non-breeding pairs had slightly more. The breeding pairs had both low and high diversity values which seemed to correlate to the stage of breeding that the pair was in (eggs and young nestlings, intermediate nestling age, and older nestling age), with the highest diversity occurring in pairs with older nestlings. They found that all parakeets in the study relied on one or two discrete calls which is consistent with having an individual signature call used for identification. They did not find any evidence for call-matching or convergence through clustering in pairs supporting their claim for individual call signatures. But, they found some evidence for convergence in calls through partitioning (the calls were found adjacent to one another in a PCO space) which could serve for minimal pair identification. Cortopassi and Bradbury inferred that for the parakeets to primarily display individually unique calls, the parakeets must have more of a need for individual identification over pair identification.

This is important because it is consistent with the information provided in lecture that signals function to provide social integration. While Cortopassi and Bradbury are unsure of the mechanism used for pair identification, they found that the parakeets use signatures in their contact calls for individual identification. The mechanism by which individual recognition occurs between the parakeets is unclear – it could be that the signature of one bird is mimicked by another to get its attention, or that an individual is given an external call/label that refers only to it that others use for identification. In either case, it is clear that Orange-Fronted Parakeets have contact calls that function as a means to individual identification (a type of social integration).