On the breeding behavior of the cock-of-the-rock (Aves, Rupicola rupicola). Bulletin of the AMNH ; v. 124, article 2

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New York : [American Museum of Natural History]
"Ethological observations of the breeding behavior of the cock-of-the-rock as observed in 1961 in the mountain forest of the Kanuku Mountains, British Guiana, are reported. Three dancing arenas were studied. At one, observations were made over a period of 20 consecutive days. The behavior of the cocks in their display arena is described, and their display attitudes and their display paraphernalia are illustrated. It was found that a clan of three cocks, each with its own terrestrial lek, joined forces to defend a social display arena some 70 feet in diameter in the mountain forest. The clan males lived in and around this arena almost continuously. The females lived apart from the males in the vicinity of a nesting cave 625 feet from the display arena. In this cave were four nests on which the females habitually slept and on which they often perched by day. The interactions between adult males, between adult males and a wandering clan of young males, and between the adult males and females are described. The adult males posture stiffly on their ground leks when a female visits the arena. They resemble bits of gold carpet on the brown floor of the forest. The manner in which the female signals a prospective mate is described. A general description of the ecology and meteorology of the Kanuku Mountains precedes a discussion of arena behavior in general. In the latter are comments on the biological advantages of this form of breeding behavior, and its probable mode of evolution. The advantages are postulated as resulting from the greater expendability of the males (a much smaller percentage of each generation is needed for the perpetuation of the species), permitting more severe selection and consequently more rapid evolutionary advancement. Arena behavior in the cock-of-the-rock is postulated as having arisen as a fortuitous result of the division of work between the sexes. This division is postulated as having resulted from two forces that may have been working simultaneously: natural selection in the direction of cryptic coloration in the parent attending the nest, and sexual selection in the direction of brighter plumage and conspicuous patterns of behavior in the male. The peculiar stationary terrestrial postures of the males on their private leks are thought to have resulted in part from relict tendencies (displacement activities) for nest building and nest care. These tendencies are postulated as having been superimposed on the pattern of courtship. The nests are built of mud droplets gathered by the female. One nest weighed 8 1/2 pounds. The carrying of this amount of mud must have required many hundreds of visits to the ground by the female. Therefore ground visiting (like nest building) is believed to be a deep-seated activity, a fixed action pattern, of the central nervous system which is far more easily diverted than dropped, which is an added reason for assuming that lek building and arena behavior evolved largely as displacement activities for nest building and nest care--activities that doubtless were once components of the behavior of the males of the primitive cotinga from which the cock-of-the-rock originated. An outline of arena behavior throughout the world is given. The hypothesis is advanced that arena behavior has a common origin in all the birds that practice it. It is courtship behavior as reshaped by emancipated males to include their non-discardable nesting tendencies, as is postulated for the cock-of-the-rock. The taxonomic conclusion is reached that, despite its manakin-like ethology, Rupicola is probably closely allied to Procnias"--P. 66-67.
p. 35-68, [10] p. of plates (2 col.) : ill., map ; 27 cm.
Includes bibliographical references (p. 67-68).