Occurrence of western scrub-jays (Aphelocoma californica) near forest edges in fragmented golden-cheeked warbler (Setophaga chrysoparia) habitat

Authors: J.A. Klassen, H.A. Mathewson

The western scrub-jay (Aphelocoma californica) is a common nest predator and has been documented depredating nests of the federally endangered golden-cheeked warbler (Setophaga chrysoparia), a woodland songbird, in central Texas. We conducted opportunistic and transect surveys for western scrub-jays across two vegetation classes (woodland and shrub-scrub) to investigate the proximity of scrub-jays to golden-cheeked warblers breeding in a fragmented landscape. We used a chi-square test to compare the number of observed and expected scrub-jay detections for each vegetation class. To investigate if scrub-jays are an edge-occupying species, we compared the distance to nearest vegetation edge of actual scrub-jay detections to a null distribution of mean random distances. We found that scrub-jays occur in areas closer to vegetation class boundaries but do not appear to prefer one vegetation type over the other. Our findings suggest that golden-cheeked warblers may have higher nest predation risk in fragmented areas of their breeding range.