Nest-site selection by the Painted Honeyeater (Grantiella picta), a mistletoe specialist

Abstract

The Painted Honeyeater (Grantiella picta) is a migratory to nomadic honeyeater with an extremely specialised diet that is ecologically linked with habitats containing mistletoe, the fruits of which form its primary diet. This paper examines nest-site selection of this little known species at the scale of the nest tree in an effort to understand better its ecological requirements. Ninety-one breeding attempts were observed between October 2004 and February 2006 in or adjacent to Binya State Forest, central New South Wales, Australia, 63 of which are analysed here. Painted Honeyeaters built nests in most of the tree species present in the study site but 78% of nests were in Yarran (Acacia homalophylla), which is the principal host for Grey Mistletoe (Amyema quandang). In total, 46% of all nests were placed in Grey Mistletoe despite its low presence in the environment relative to non-mistletoe arboreal substrates. The prevalence of mistletoe in host trees selected for nests was significantly higher than in randomly sampled hosts and the mean rate of mistletoe parasitism was also significantly higher. Painted Honeyeaters tended to orientate their nests to the north-east, consistent with reducing direct exposure to the afternoon sun, with greater variation being evident for nests placed in mistletoe. Nest trees were significantly taller than randomly sampled trees and the vertical distribution of nests in tree crowns and mistletoe clumps was non-random and suggested that reducing the risk of predation might drive the pattern. When considered holistically, proximity to mistletoe food resources, reduction of predation risk and provision of a suitable microhabitat may interact to produce the pattern of nest-site selection observed in this study. Management actions for this declining species should include maintaining a diverse woodland vegetation community supporting adequate mistletoe populations over the long-term.