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Cooperative Breeding in the Frugivorous Toucan Barbet (Semnornis ramphastinus)
Carla Restrepo and Marta Lucy Mondragón
Vol. 115, No. 1 (Jan., 1998), pp. 4-15
Published by: American Ornithological Society
Stable URL: http://www.jstor.org/stable/4089106
Page Count: 12
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Cooperative breeding is rare in frugivorous birds, presumably because traits associated with frugivory do not favor permanent group living and helping behavior. We studied the Toucan Barbet (Semnornis ramphastinus) in southwestern Colombia to understand the possible benefits of group living and helping behavior in one of the few frugivorous birds exhibiting such behavior. Toucan Barbets lived in permanent groups, defended a territory year-round, roosted and nested in tree cavities built by themselves, and fed mostly on fruits. Toucan Barbet groups were composed of a breeding pair and their offspring; groups were significantly smaller during the breeding (x̄ = 2.7 individuals) than during the nonbreeding season (x̄ = 3.1 individuals). Sixty-two percent of pairs had helpers, which incubated eggs, brooded and fed nestlings, and defended nestlings against predators and cavity usurpers (mainly the Plate-billed Mountain-Toucan [Andigena laminirostris]). Pairs with helpers produced more fledglings (x̄ = 1.3) than pairs without helpers (x̄ = 0.5). We suggest that the increase in reproductive success of pairs with helpers explains why cooperative breeding is favored in this species. Furthermore, we suggest that frugivory by itself does not impede the evolution of delayed dispersal and helping behavior.
The Auk © 1998 American Ornithologists' Union