Breeding biology and reproductive success of the Spectacled Tetraka Xanthomixis zosterops (Bernieridae) in a rainforest of Madagascar

Abstract

The Spectacled Tetraka Xanthomixis zosterops is a sexually monomorphic species in a family (Bernieridae) endemic to Madagascar and is found in various humid forest types. It is categorised as Least Concern by the IUCN. Despite its commonness, the biology of this species is little known. This study focused on its breeding biology and took place from September to December 2010 at Talatakely, Ranomafana National Park, Madagascar. Thirty nests were monitored and incubating birds were marked. Direct observations were made associated with nest building, incubating and nestling periods. Habitat structure was assessed to detect nesting site choice. The breeding episode, from the nest-building stage to fledging of the last chick, lasted on average 45 d. Only one individual, probably the female, in each presumed pair incubated eggs and brooded hatchlings, whereas both parents fed and cared for the nestlings. The mean clutch size was 2.4 ± 0.2 egg per nest (range 1–3, n = 24), the incubation period averaged 17.7 ± 0.3 d (range 16–19, n = 10), and the nestling period averaged 14.7 ± 0.3 d (range 14–15, n = 3). We estimated the reproductive success to be 13.6% (n = 59 eggs). Nest predation was believed to be the primary cause of nesting failure with 24 eggs (40.7%) and 18 (64.3%) nestlings being predated.