Physical and Behavioral Factors in Sociality and Evolution of Certain Parrots (Aratinga)

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Abstract
Orange-fronted parakeets [Aratinga c. canicularis] of 2 races and Aztec parakeets [Aratinga astec] were observed in aviaries and confined in a cage in various combinations to reveal the importance of specific, racial, and individual characteristics in sociality. A male orange-front of the race eburnirostrum paired with an Aztec female when deprived of the sight of his own kind. These 2 birds maintained their bond, except when other individuals of the race eburnirostrum were placed in the cage, whereupon the male always paired with them. The male typically ignored orange-fronted parakeets of the race canicularis except to greet them. Apparently greeting is evoked by species-specific physical characters (orange forehead, for example) but further progress toward sociality requires cooperation by the bird toward which the display is directed. An Aztec parakeet (other than the one with which the male paired) was painted variously to resemble an orange-fronted parakeet. The disguise evoked only incipient greeting and recognition. An individual ot the race eburnirostrum never before seen by the male used in the experiments was accepted only after a period of several days, while all ot the male''s former flock-mates, when introduced into the cage, were immediately acepted by the male. This indicates that the male reconized the latter birds by individual or flock characteristics. A female eburnirostrum of the same flock as the male and previously accepted by him in the experiment was painted with green paint to conceal the orange forehead. Acceptance of the disguished bird by the male was delayed for an hour and the greeting-recognition display of the male was interspersed with threat. Replication of the experiments was conducted and results substantiated the initial hypotheses. Parrots have diverged phenotypically much further than their interspecific fertility in captivity would indicate. Few wild hybrids are known, however, and it is hypothesized that the phenotypic variety together with clannishness and ability to recognize individuals or flock-mates accounts for isolation of species in the wild. It is hypothesized that these factors promote rapidity of evolution by re-enforcing the effects of slight geographic isolation.

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