Nest-site selection and breeding ecology of Streaked Wren-Babbler (Napothera brevicaudata) in a tropical limestone forest of southern China

Background: The breeding information of most birds in Asian tropical areas, especially in limestone forests, is still poorly known. The Streaked Wren-Babbler (Napothera brevicaudata) is an uncommon tropical limestone bird with a small range. We studied its nest-site selection and breeding ecology, in order to understand the adaptations of birds to the conditions of tropical limestone forest in southern China. Methods: We used methods of systematical searching and parent-following to locate the nests of the Streaked Wren-Babbler. We measured characteristics of nest sites and rock cavities. Data loggers and video cameras were used to monitor the breeding behavior. Results: All the observed nests of the Streaked Wren-Babbler were placed in natural shallow cavities or deep holes in large boulders or limestone cliffs. The great majority (96.6%) of Streaked Wren-Babbler nests had three eggs with an average fresh weight of 3.46 ± 0.43 g (n = 36, range 2.52-4.20 g). Most (80.4%) females laid their first eggs between March and April (n = 46). The average incubation and nestling period of the Streaked Wren-Babbler was 10.2 ± 0.4 days (n = 5, range 10-11 days) and 10.5 ± 0.8 days (n = 6, range 9-11 days), respectively. Most (87.9%) nests had at least one nestling fledge between 2011 and 2013 (n = 33). Conclusions: Our study suggests that several features of the breeding ecology of the Streaked Wren-Babbler, including building nests in rocky cavities, commencing breeding earlier than most species, and reducing foraging times during the incubation period, are well-adapted to the unique habitat of tropical limestone forest.