Nest Site Selection and Breeding Success in Large Australian Honeyeaters: Are There Benefits from Being Different?

Abstract

Red Wattlebird Anthochaera carunculata (n = 97) and Noisy Friarbird Philemon corniculatus (n = 229) nests were monitored over eight breeding seasons in eucalypt woodland in northern New South Wales. Red Wattle-birds nested in Eucalyptus viminalis and E. bridgesiana more frequently than expected from their relative abundance at the site. Noisy Friarbirds avoided stringybarks (E. caliginosa) but selected other eucalypts disproportionately. Nest success was similar in the two species (33% in Red Wattle-birds and 38% in Noisy Friarbirds), despite Friarbird nests being placed further horizontally from the base of the nest tree and being more conspicuous. The similar success may be because Noisy Friarbird nests are more inaccessible to mammalian predators and Red Wattlebird nests are less conspicuous to avian predators. In addition, Noisy Friarbirds tend to be more aggressive to avian predators than Red Wattlebirds, which may allow them to benefit from nests that have a good view of their surroundings. Neither species showed a relationship between nest success and nest height, horizontal distance from the base of the tree, nest tree height and trunk diameter or nest conspicuousness. Noisy Friarbird nests in E. blakelyi, although chosen most frequently, were less successful than those in other tree species and nests around mean height were less often successful than those higher or lower. The difference in nest locations between the species and diversity of nest sites chosen within each species could reduce the chance of a nest predator developing search images for specific nest locations. The suggestion that Noisy Friarbird nests in less common locations are more likely to be successful supports this hypothesis. Nests at the edge of the habitat patch and near tracks used by humans did not differ in their success rate from nests in the centre of the patch or away from tracks.