关键词: 赤腹鹰, 繁殖成效, 巢址选择, 巢防卫

Abstract:

Objective: Based on the survey of nest site characteristics, nest defensive behavior and reproduction result of Chinese sparrowhawk, the mechanism of nest selection and reproduction efficiency of Chinese sparrowhawk are analyzed, and the influence factors on breeding success rate are revealed in order to provide valuable advices for its conservation. Method: According to the different defensive intensity, we divided nest defensive behaviors into 4 levels, and counted numbers of calls of birds within 10 min. We measured the parameters of nest site, including specie of nest tree, nest height above ground, diameter at breast height, altitude, area of tree-crown, slope position, slope gradient, slope aspect, front view of nest, nest distance fromroad, building, or water, vegetation characteristic within 20 m radius sample circle around nest tree. The data were analyzed with SPSS 23. Result: In 2016 and 2017, we found totally 51 nests of Chinese sparrowhawk, among which 35 nests were monitored byinfrared camera, and 661 306 monitoring photos were taken. In 2016, the hatching rate was 71.4%, and the fledging rate was78.2%. In 2017, the hatching rate was 82.5%, and the fledging rate was 61.5%. Through the inspection of the monitoring photos in the infrared camera, it is found that the main reason of the breeding failure of Chinese sparrowhawk was that the eggs or nestlings were preyed on, and the predators included King rat snake (Elaphe carinata)(n=9 nests), Eurasian jay(Garrulus glandarius)(n=1 nest), Siberian weasel (Mustela sibirica)(n=1 nest), and Crested goshawk (Accipiter trivirgatus)(n=1 nest). The farther the nest tree was from road, the more the male cried (r=0.68, n=12, P < 0.05, Spearman), and the higher the female's nest defense level (r=0.42, n=42, P < 0.01, Spearman). Breeding success rate was negatively correlated to the distance from nest tree to road(r=-0.45, n=47, P < 0.01, Pearson), the other factors did not have a significant positive correlation to breeding success rate or hatching rate. The closer the nest tree was to building(r=-0.56, n=47, P < 0.01, Pearson) and road(r=-0.35, n=47, P < 0.05, Pearson), the higher the height of the nest from the ground was. Linear regression analysis of the nest height (y, m) and the distance from nest to building(x, m) showed a relation:y=12.75-0.01x(R²=0.32, n=47, P < 0.01). The principal component analysis showed that there were 8 main factors affecting Chinese sparrowhawk's nest site selection. The size of nest trees and forest quality around nest site played key roles in nest selection, human activity area and water source also influenced nest selection partly. Conclusion: Chinese sparrowhawks tend to nest far away from human activities, but by adapting to human activity, the nesting near to road had a higher fledging rate. Chinese sparrowhawks with stronger nest defensive behavior tend to nest far away from anthropic zone. Chinese sparrowhawks close to the human activity area will choose to build their nests at a higher position. Chinese sparrowhawk usually nests in big tree in leafy forest with rich species of trees, sparse grass and shrub, and near to water source.

Key words: Chinese sparrowhawk, reproductive efficiency, nest site selection, nest defensive behavior