Breeding Biology of White-Winged Trumpeters (Psophia leucoptera) in Peru

Abstract

-I studied the breeding biology of a population of White-winged Trumpeters (Psophia leucoptera) in undisturbed lowland rain forest in Manu National Park, southeastern Peru. At this study site, it was possible to habituate trumpeters to humans, allowing groups to be followed and observed at distances of a few meters for entire days. I found that Whitewinged Trumpeters lived in cooperatively polyandrous groups of 4 to 13 individuals that defended permanent year-round territories. Clutches that averaged three eggs were laid by the dominant female on the floor of elevated cavities in trees. Eggs were incubated for about four weeks, primarily by the group's dominant male and female. Chicks hatched around the end of October at the beginning of the rainy season. If at least one of the brood survived, a subsequent clutch was not laid until the following breeding season. Predation on eggs and chick mortality resulted in an average of 1.6 young per group-year surviving to adulthood. White-winged Trumpeter chicks were precocial and left the nesting cavity the day after they hatched, able to walk and climb. Chicks were dependent on older birds to provide them with all of their food for over three weeks and were still receiving more than one-half of their food from adults at two months. Trumpeters reached sexual maturity at about two years of age, at which time both male and female offspring dispersed from their natal groups. Received 3 June 1993, accepted 24 October 1993. THE FAMILY PSOPHIIDAE (order Gruiformes) includes three species: the White-winged Trumpeter (Psophia leucoptera), the Gray-winged Trumpeter (P. crepitans), and the Green-winged Trumpeter (P. viridis). Little is known about any of the trumpeters, which are hen-sized terrestrial birds found primarily in the rain forests of the Amazon and Orinoco basins (Sibley and Monroe 1990). Published information on the breeding biology of wild trumpeters consists principally of observations that local people offered to turn-of-the-century naturalists, and these reports are anecdotal and frequently con1 Present address: Department of Biology, University of Louisville, Louisville, Kentucky 40292, USA. tradictory. For example, wild Gray-winged Trumpeters have been reported to nest on the ground, in the branches of trees, in nesting cavities in trees, and in the crowns of palm trees (Schomburgk 1848, Lloyd 1897, Penard and Penard 1908, Beebe and Beebe 1910, Chubb 1916, Beebe et al. 1917). Clutch sizes of 2 to more than 10 white, green or blue eggs have been reported (Lloyd 1897, Penard and Penard 1908, Beebe and Beebe 1910, Chubb 1916, Beebe et al. 1917). Furthermore, it has been suggested that this species nests colonially, with five to six pairs building nests in adjacent trees (Beebe et al. 1917), and that the birds nest communally, with all females in the group laying eggs in a single