Nest concealment but not human visitation predicts predation of New Holland Honeyeater nests

Abstract

The vegetation characteristics surrounding 31 New Holland Honeyeater nest-sites were measured in two study sites in the Mount Lofty Ranges, South Australia, to determine if predation outcome (depredated or fledged) covaried with vegetation parameters. We controlled for the influence of human visitation level on nesting outcome through an experimental design, randomly allocating each encountered nest to low or high levels of visitation by the observer. We compared nest vegetation parameters for the two visitation level groups and found no significant differences across experimental treatments. There was also no effect of human visitation level on predation outcome. In contrast, nest-concealment variables (percentage cover above, below, at sides and canopy cover) were significantly related to levels of predation, as revealed using binary logistic regression. In particular, the variable nest concealment to the sides was important for predation outcome, with lower levels of predation at concealed nests. The identity of the nest predators remained unknown.