AVIS-IBIS

Birds of Indian Subcontinent

Pair and Group Reproductive Success, Polyandry, and Cooperative Breeding in Harris' Hawks

Publication Type:Journal Article
Year of Publication:1987
Authors:Bednarz, JC
Journal:The Auk
Volume:104
Issue:3
Date Published:1987
ISBN Number:00048038
Keywords:Accipitridae, Mexico, Parabuteo, Parabuteo unicinctus
Abstract:The average size of Harris' Hawk (Parabuteo unicinctus) social units in New Mexico was 2.7 individuals, and pairs were most common (49%; n = 61). Groups of more than two hawks included both adult- (74%) and immature-plumaged (26%) members (n = 76). Immatures rarely provided food to nestlings, but adult supernumeraries did. Electrophoretic analyses of two groups containing two adult-plumaged males did not suggest polyandry. At least in southeastern New Mexico, Harris' Hawk groups consist primarily of a monogamous pair with "helpers." Pairs and groups showed no differences in clutch size, number of young produced per successful nest, or number of offspring fledged per year. Pair nests failed less often (16%) than group nests (46%) during the incubation period. Groups reared larger offspring and tended to initiate second nests more frequently than pairs. The overall lack of correlation between reproductive output and group size suggests that kin selection has not been a major influence in the evolution of the Harris' Hawk breeding system.
URL:http://www.jstor.org/stable/4087535
Short Title:The Auk
Taxonomic name: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith