The Breeding Ecology of the Boreal Owl (Aegolius funereus beickianus) in Gansu Province, China
The Breeding Ecology of the Boreal Owl (Aegolius funereus beickianus) in Gansu Province, China
Yongke Zhu1,2, Yun Fang1, Songhua Tang1, Yuan Gu3, Jinming Zhao4, Wolfgang Scherzinger5 and Yue-Hua Sun1*
ABSTRACT
The boreal owl (Aegolius funereus) has a circumpolar distribution, typically inhabit extensive conifer forest of higher age classes in the northern hemisphere. Breeding biology, reproductive strategies, and behavioural ecology of these nocturnal birds are well studied in Europe and North America. However, the knowledge of the subspecies of boreal owl (A. f. beickianus) in the coniferous forests at high mountainous altitude of the Qinghai-Tibet Plateau is still limited. We spent 10 years studying the breeding biology of A. f. beickianus in Lian Hua Shan Nature Reserve (Gansu Province), where we could first confirm the occurrence of this small forest dwelling owl in 1995. During breeding seasons (2003-2009, 2017-2019), we checked nest boxes and recorded the basic breeding data. Thereby a total of 51 broods were found with an average of 5.1 ± 1.7 broods per year. The mean egg mass and volume was 12.42 ± 1.36 g and 12.85 ± 0.79 mm3, respectively. Mean clutch size per brood was 2.61 ± 0.64. The mean number of fledglings was 1.25 ± 0.31 per nesting attempt and 2.07 ± 0.38 per successful brood. Nestling period lasted 35.75 ± 2.80 days in total, but was divided in two stages: in the first stage, which lasted 16.75 ± 1.48 days, the female stood in the breeding hole with its nestlings. In the second stage, which lasted 17 ± 4.34 days until the fledglings left their nest, the female stood outside the hole. The individual fledglings left the nesting site in intervals of 2.55 ± 1.92 days.
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