Research On Wintering Common Cranes(Grus Grus) In Beijing Yeyahu Wetland Natural Reserve

The population size, food selection and habitat selection of Common cranes(Grus grus)wintering Beijing Yeyahu Wetland Natural Reserve had been studied from 2005 to 2007.According to plentiful fieldwork and particular data analysis, we found the population size of common cranes wintering in Yeyahu were not less than 200, Cereal was the main component of food sources for wintering common cranes, the grade of selectivity of 4 main habitat type were maize land, marsh, reserve and grassland(in descendible sequences). The detailed extent is as follow:1. 5 times population census of wintering common cranes had been carried out in Yeyahu natural reverse from December, 2006 to Feburary, 2007, separately recorded wintering common cranes from 215 to 283, average number were 245±27 (x|- ±SE).Based on these results, we deduced that the total number of the common cranes wintering in Yeyahu Natural Reserve were not less than 200. At the same time of population census, the age structure of wintering common cranes had also been examined. The result showed that the parameter of age structure — Recruitment Ratio was 10.78% in the winter of 2006/2007, at the range of normal value (10%～15%) .In total 48 family flocks, the most age structure was "two adults, one juvenile", accounting for 43.75%; "Two adults, one juvenile" was in the next place, accounting for 22.92%, "Two adults, none juvenile" was in the third place, accounting for 18.75%, and other age structure was seldom.2. Food composition and selection of wintering common cranes were studied by analyzing the feces from 2005 to 2007. Common cranes in Beijing were herbivorous in Yeyahu. Total 16 plant species which belong to 7 families were found in common crane's feces. Cereal was the main component of food sources for wintering common cranes, accounting for 89.50%, which is maize(Zea mays), broomcorn (Sorghun bicolar), soybean (Glycine max) and wheat (Triticum aestivum) . Besides agricultural plants, some species of natural plants in the wetland which belong to 5 families could also be found in their feces, accounting for 9.13%. Besides plants, itwas found some small stones in common crane's feces, accounting for 10.33% of total feces composition. According to ANOVA test, it was founded that there was evident difference in the compositions of maize in the whole wintering periods (F= 101.35, df=359, p=0.00<0.05) .The proposition of maize is extraordinary high in the prophase of wintering period; where after, the value was graduate descending until February.3. The result of habitat selection showed that the grade of selectivity of 4 main habitat types were maize land, marsh, reserve and grassland (in descendible sequences). The logistic regress model has been built based on 3S Technology. The model showed that food was the most important factor impacting on the common cranes' habitat selection. Furthermore, the appearance frequencies of common cranes were positively relative to the habitat variables of distance forest plantation(DFP),distance to fish pound (DFP) and distance to paved roads(DPR); and were negatively relative to the habitat variables of distance of shrub (DSH), distance to villages(DVI),distance to farmtown buildings(DTB),distance to other building(DOB),distance to winter fisher(DWF).4. Based on these results, 8 suggestions have also been proposed for the conservation work of wintering common cranes wintering in Yeyahu Natural Reverse.