Nest-site Selection and Breeding Success of the Rufous-tailed Shrike

The study about the nest-site selection and breeding success of the Rufous-tailed Shrike Lanius isabellinus was analyzed based on the measurement of nest characteristic parameter from 58 nests in the breeding season from May to July,2011 in Anxi Hyper-Arid Desert National Nature Reserve which locates in northwestern Gansu province(N40°21′~ 40°22′,E 96°13′~ 96°14′,Altitudes 1 306 m).All the 58 nests were built at the main braches of trees 2.0 and 2.5 m above the ground.Based on the principal components analyzing on nest success related to the nest site by the nest characteristic parameters,three parameters,nest height above the ground,height and DBH of nest tree,were the most important factors in the nest sit selection.The breeding success of 49 nests was measured,higher reproductive success occurred in those nest built in tree of Branchy Tamarisk Tamarix ramosissima which has higher number of branch(n=5) than those built in Diversifolious Poplar Elaeagnus angusifolia(n=43) and Russianolive Populus euphratica(n=1).The higher canopy density of Branchy Tamarisk may response to the higher breeding success.The clutch size varied from 1 to 6(n=30),5 and 4 eggs was the most common clutch size(n=18 and 7).The difference between clutch size and reproductive success ratio was not significant(Chi-square test,χ2=3.921,P0.05).Among the 54 nests measured and not measured,37 nests were success(68.52%).All the failed nests were destroyed by intra-specific birds.The amount of failed nests was decrease as the distance increase from neighbor nests.Therefore,we suppose the intra-specific competition resulted from higher local population density.