北京湿地越冬灰鹤食性的初步分析

Food Selection of Wintering Common Crane(Grus grus) in the Wetland of Beijing

2005年12月～2006年3月，采用粪便分析法对北京野鸭湖湿地自然保护区和密云水库北部地区越冬灰鹤（Grus grus）的食性进行了研究。结果表明，灰鹤冬季为植食性，主要的食物有5科13种。谷物为其冬季食物的主要来源，占食物总量的76．40％。除农作物外，灰鹤也取食湿地植物的种子或植株，但仅占食物总量的13．27％。将野鸭湖灰鹤和密云水库灰鹤的食物组成进行比较，发现两越冬种群虽然都主要以农作物为食，但野鸭湖灰鹤以取食玉米（Zea mays）为主，密云水库越冬灰鹤取食最多的食物则为高粱（Sorghun bicolar）。

Form December 2005 to March 2006, food composition and selection of wintering common crane （ Grus grus） were studied by analyzing the feces in 2 main winter habitats of common cranes Yeyabu Wetland Reserve Area and the North area of Miyun Reservoir. Common cranes in Beijing are herbivorous in the winter. Total 13 plant species which belong to 5 families were found in common crane＇s feces. Cereal were the main component of food sources for wintering common cranes, accounting for 76.40%. 4 species of cereal has been found in common crane＇s feces, which is maize（ Zea mays）, broomcorn （Sorghun bicolar） , soybean（ Glycine max）and wheat（ Triticum aestivum）. Similar as human being＇s activity, common cranes mainly forage cereal＇ s seeds, where were left in the farmland after harvest. Besides agricultural plants, total 8 species of natural plants in the wetland which belong to 5 families can also be found in their feces, including Bidens tripartita, Echinochloa rumentacea , Echinochloa caudate , Bolboschoenus planiculmis , Potamegeton pectinatns , Eleocharis congesta, Glycine sojai and Satvvel, accounting for 13.27% of the total amount of food composition. The seeds or fruits of natural plants seem to be more flavorful to common cranes and they can provide energy and nutrition than other part of plants. Besides plants, it was found some small stones in common crane＇s feces,＂ accounting for 10.33% of total feces composition. They might be eaten by common cranes intently in order to digest foods. Comparing the diet composition of common cranes between Yeyahu and Miyun Reservoir, it was found that maize is the main food for common crane in Yeyahu wetland, accounting for 51.94% of total food component. In Miyun Reservoir broomcom is the main food for them, accounting for 26.54%. Based on these results, it was deduce that common crane＇ s main food source was not one single cereal type in winter; it had relationship with the main planting cereal type in the habitats. Maize becomes the main food source for common crane in Yeyahu because local people take maize as their main planting cereal. Similar explanations could be used to explain why broomcom was the main food source in Miyun Reservoir. According to field work, many dangerous factors threaten wintering common crane＇ s foraging in the 2 habitats. For example, winter fishing is a popular entertainment in these 2 wetlands in winter, which can disturb common crane＇s foraging and resting. Firing straws in these two places can significantly decrease common crane＇s food sources in winter. In order to protect common cranes, the following suggestions were pointed out . First, local government should control or forbid the activity of winter fishing in habitats for common cranes. Second, local people should be advised not to fire straw and not to carry out other farming activates which can disturb common crane＇s foraging. Third, local wildlife managers should provide some cereal in winter, such as maize or broomcorn. It would help common cranes to pass through the winter time safely. At last, the North area of Miyun Reservoir should set up new Nature Reserve Area to protect common cranes and other wintering wildfowl, such as Ruddy （ Tadorna ferruginea） , Bean Goose （Anser albifrons） , etc.