yellow warbler (dendroica petechia) breeding biology and parasitism by the shiny cowbird (molothrus bonariensis) inboqueron, puerto rico

Aspects of the breeding biology of the Yellow Warbler (Dendroica petechia) and ShinyCowbird (Molothrus bonariensis) parasitism were studied in Boqueron, Puerto Rico from 2001 to 2002.Fifty-seven percent (n = 12) of warbler nests were parasitized. Survival of parasitized nests was lowerthan non-parasitized nests. Thirty-four percent of nests (n = 21) survived until fledging of cowbird or warbler chicks, with predation the major cause of nest failure (88%). Nineteen nests fledged warbleryoung and two nests fledged cowbird young, but no nest fledged warbler and cowbird youngsimultaneously. The Yellow Warbler presented three responses toward parasitism: acceptance andincubation, egg burial, and nest desertion. No warbler young fledged from nests that accepted parasitism.Nests with buried cowbird eggs fledged an average of 2.00