Reproduction Of Lanius Isabellinus In Extremely Arid Desert Region In Guazhou,Gansu

The study of avian reproduction has a long history. The author studied the reproduction of desert shrike (Lanius isabellinus) in An xi desert nature reserve in Guazhou, Gansu, in2011and2012. L. isabellinus is one of these breeding birds in Guazhou, and it has obvious sexual dimorphism which makes it is easy to distinct the male and female. L. isabellinus always nests in trees. Egg color of desert shrike is light cyan. Mean egg length is22.05±1.00mm, mean egg width is16.67±0.57mm. The mean egg volume is3.14±0.32cm3, mean egg weight is3.32±0.33g. The analysis of143(excluding parasitized nests) eggs in2011suggest that Mean egg length, mean egg width, the mean egg volume and mean egg weight are21.97±1.06mm,16.52±0.55mm,3.07±0.30cm3and3.25±0.31g respectively. The analysis of71eggs in2012suggest that Mean egg length, mean egg width, the mean egg volume and mean egg weight are22.28±0.93mm,16.54±0.50mm,3.12±0.29cm3and3.30±0.30g. The variation of egg volume among the three years is not evident(χ2=304.53,df=284,P=0.192), and the same with egg weight(χ2=314.22,df=284,P=0.105). The analysis of the three years suggest clutch size is2～6with the average clutch size is4.74±0.66(n=66). The most familiar clutch size is, with the percentage of68.18%,58.06%,84.21%from2010to2012.The female incubate all the eggs, and all incubating rate is over76%. With the increasing of incubation period, the incubating rate of female is decreasing. Both the male and female feed the nestlings. The reproduction success in2011and2012were71.11%(n=45) and71.43%(n=28). The fledging success in2011and2012are98.25%and93.51%。All of the58nests were built1.5～3.0m above the ground at the main braches of trees. The analysis of principal components suggests that the nest height, the tree height, DBH and the diameter of trunk were the most important factors in nest-site selection. And these were the adaption with the windy day in the study area.Both female and male feed the nestlings. Those nestlings took positions near the parents such as1and2to get more food; and those nestlings stay at4and5got little food. Nestlings would not get food without begging. The begging intensity of nestlings was lesser in early stage than those in other stages. However, the begging intensity varied in the three stages, higher in mid and later stages. The male delivered food with a significantly higher frequency than the female (χ2=22.323, P<0.001)...