Can Nest Predation Explain the Timing of the Breeding Season and the Pattern of Nest Dispersion of New Holland Honeyeaters?

We tested the following two predictions of the hypotheses that predation rate may select for nest spacing and winter breeding in New Holland honeyeaters: (a) the level of nest predation should be lower during the breeding season than outside it, and (b) clumped nests should show a higher predation rate than more dispersed nests. Artificial nests, containing budgerigar and artificial eggs, were set out in four different seasons and in two different configurations: clumped and spaced. Clumped nests suffered higher predation than spaced nests but there was no seasonal difference in total predation rates. Birds accounted for 67% of predation events for which the predator was identified. Among nests that were preyed on by birds, there was a highly significant effect of spacing, indicating that birds were responsible for the higher predation on clumped nests. Hence, these results support one prediction of the predator-avoidance hypothesis for territoriality, but do not support the notion that winter breeding may have evolved as a strategy to avoid predation by snakes.