Notes on the biology of the Cock-of-the-rock (Rupicola rupicola)

Abstract

This paper, based on a three-month visit to southern Guyana early in 1970, presents information on Rupicola rupicola supplementary to that obtained by Gilliard (1962) in the same area. In the course of observations at a dancing ground, a female was seen to visit a male on his court, to approach him and to nibble at his modified secondary feathers while he remained in static display on the ground. This was thought to represent precopulatory behaviour, but mating itself was not seen. Four nest-sites were regularly checked; eggs were laid between 2nd March and 25th April. A study of museum specimens shows that the moult mainly takes place in the middle of the year and almost certainly must overlap the breeding season. The female's nest-building behaviour is described. Saliva must be used to strengthen the mud used in the nest structure, since in its natural state the mud is too friable to hold together or to adhere to a rock surface. Details are given of two clutches of eggs. The incubation periods for two other clutches were 27-28 and 28 days. The fledging period was not ascertained as the young disappeared prematurely from the one nest that was regularly checked. A description is given of a 10-day-old nestling hatched in captivity. The food (exclusively fruit) recorded in samples collected from below nests and from a display ground from January to April is tabulated and discussed. 71% of the fruits recorded were from trees of four families (Araliaceae, Burseraceae, Palmae and Lauraceae) which are of general importance for neotropical frugivorous birds. © 1971 Verlag der Deutschen Ornithologen-Gesellschaft.