Post-Fledging Ecology and Behavior of an Endangered Species: The Golden-Cheeked Warbler

The post-fledging period is often a period of low sur-vival and rapid change in songbird behavior (e.g., habi-tat use, mobility, foraging rate). Information aboutthe post-fledging period is therefore critical for effec-tive management and conservation of birds. We in-vestigated the post-fledging ecology of the endangeredGolden-cheeked Warbler (Setophaga chrysoparia). Weradio-tracked fledglings (n = 23) for at least four weeksand monitored habitat use, estimated survival, and howfledgling and parental behavior changed as fledglingsaged. Overall, fledgling habitat was composed of Ashejuniper (Juniperus asheii; 74.7%), and oak (Quercusspp.; 20.7%). Daily survival rate of fledglings duringthe first four weeks out of the nest was 0.985 (95%CI = 0.971-0.993). Whereas the proportion of juniperaround fledglings was positively associated with theirprobability of survival, we found considerable uncer-tainty in the effects of habitat. As fledglings aged andforaged independently, their use of oaks increased, andthey were more successful at foraging in oaks com-pared with junipers. Adults remained with fledglingsfor a minimum of five weeks. Female provisioningrates for fledglings were greater than male rates, butboth parents fed less as fledglings aged. The sex ofthe parent caring for the fledging, however did not af-fect fledgling survival. Previous research recommendsmaintaining mature juniper-oak forests for breedingadults and it appears this recommendation also holdstrue for fledglings.