AVIS-IBIS

Birds of Indian Subcontinent

Brood Parasitism, Nest Predation, and Season-Long Reproductive Success of a Tropical Island Endemic

Publication Type:Journal Article
Year of Publication:1997
Authors:Woodworth, BL
Journal:The Condor
Volume:99
Issue:3
Date Published:1997
ISBN Number:00105422
Keywords:Icteridae, Molothrus, Molothrus bonariensis, Puerto Rico, South America, Vireo, Vireo latimeri, Vireonidae
Abstract:The Puerto Rican Vireo (Vireo latimeri) is a single-island endemic resident on Puerto Rico. The Shiny Cowbird (Molothrus bonariensis), a generalist brood parasite native to South America, arrived on the island in 1955 and has established itself as a breeding resident. To determine the impact of the exotic cowbird on vireo reproductive success, I studied the demography of marked Puerto Rican Vireos in Guánica Forest, Puerto Rico, in 1990-1993. Vireo breeding season length varied among years (69-106 days), apparently influenced by rainfall. The primary causes of reproductive failure were nest parasitism and nest predation. Cowbirds parasitized 73-83% of vireo nests. Parasitism reduced the number of vireos fledged per successful nest by 82%, primarily through decreased hatching success and fledging success. Vireos did not abandon nests in response to cowbird egg-laying, but frequently deserted if cowbirds removed host eggs. Native avian predators and exotic mammalian predators together caused the demise of about 70% of all nest attempts. As a result, daily nest survival rate was low (0.93 ± 0.01), and only 13-19% of nests fledged vireo or cowbird young. Pairs renested after failure and attempted to raise second broods. Females in this population attempted two to six nests per season and fledged an average of 1.33 vireos in 1991 and 0.24 vireos in 1993. The combination of restricted breeding season, high predation and parasitism rates, large impact of parasitism on reproductive output, and low seasonal fecundity of females suggests that, despite high survival rates, the Puerto Rican Vireo is in danger of extirpation from portions of its range.
URL:http://www.jstor.org/stable/1370473
Short Title:The Condor
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