The Breeding Biology of the Dusky Honeyeater Myzomela obscura in the Northern Territory, and the Importance of Nectar in the Diet of Nestling Honeyeaters

Abstract

The breeding biology of the Dusky Honeyeater Myzomela obscura is poorly known, despite the species’ wide distribution and use of a broad range of habitats. In the Northern Territory, breeding was recorded in all months, but just over 50% of estimated laying dates were in April and May, corresponding with the transition from the wet to the dry season. In Darwin, nests were placed 1.0 to 9.0 m above the ground in a variety of trees or tall shrubs, including exotics. The size of clutches or broods never exceeded two (n = 9). At two closely observed nests, the incubation period was 12.4 and 12.75 days, similar to another myzomeline honeyeater. Nest-attentiveness was ~65% over 2 days at one nest, similar to the few temperate-zone Australian honeyeaters for which such data are available. The nestling period at the only successful nest that we observed was 14.3 ± 0.7 days, consistent with slightly smaller species in other honeyeater genera. Unlike most honeyeater species, nestling Dusky Honeyeaters hatched with much down. Diurnal brooding represented 20–28% of the presumed female’s time during the first 4 days after hatching, but had ceased by Day 6, earlier than in temperate-zone honeyeater species. The mean rate of food provisioning was very low (8.9 feeds/h) compared with that of most other honeyeater species studied to date. Evidence suggests that Dusky Honeyeaters may feed their young largely on nectar.