Predation and Antipredator Behavior at Guianan Cock-of-the-Rock Leks

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Abstract
I documented predator attacks and antipredator behavior at four display sites of Guianan Cock-of-the-Rock (Rupicola rupicola) in Suriname from 1980 to 1985. Most observations were made at a large lek that averaged 55 territorial males, with supplemental data on display groups of 1, 2, and 6 males. Males at the main lek were attacked by 6 species of raptors, 1 mammal species, and 1 snake species. A total of 56 attacks and 2 kills by raptors were observed (0.22 attacks/day). Two kills of displaying males by the snake Boa constrictor were also observed. Male Cock-of-the-Rock were very wary. I observed 832 spooks (complete or partial flushes) at the Main Lek, more than 90% of which were apparently false alarms. Males at the smaller display sites were much less likely to spook. The raptor attack rate was inversely correlated with group size, supporting the hypothesis that social antipredator behavior reduces risk for displaying males. There was no evidence that peripheral or young males were especially vulnerable to predators. Snake predation represents a previously unrecognized cost of lek display for tropical birds. The Cock-of-the-Rock failed to exhibit any effective antipredator behavior against snakes and may rely for protection on the infrequency with which snakes locate leks.