Diet And Activities Of Wintering Tundra Bean Geese Anser Fabalis Serrirostris At Shengjin Lake, NNR, Anhui Province

Shengjin Lake is one of the most important floodplain along the Yangtze River, and it located in City Chizhou, Anhui province. It connects the Yangtze River by Huangpen Sluice, and the weather here is monsoonal. Also the huge hydrological flooding water level results into abundant food at the lake and it attracts thousands of water birds to come here. The Bean Geese are the most common birds here, and all birds examined closely were of the Anser fabalis serrirostris subspecies. The maximum count 41 457 represents 60% of the estimated global population of this subspecies and confirms that Shengjin Lake is one of the most important sites in the flyway for this subspecies.Every year, the Bean Geese arrive at Shengjin Lake in October and maximum at middle December, leaving during March - April. In Recent years, because of the rising coverage of Carex, the number of Bean Geese in Shengjin Lake is increased rapidly at first and due to the changes of hydrological environment and rainfall the number is then decreased. The beaches of Carex are their most favorite habitat, and the BG mainly feed on Carex and spot of rice at the beginning of the wintering days. When refer to middle of the wintering days, they mainly rely on Trapa and small proportion of winter wheat. At the last of the wintering days, they return back to the beaches of Carex again and feed on Carex mainly.We have learned from the time budgets of Bean Geese on Carex that the two main activities of Bean Geese are feeding and resting, and they take 63.83% and 15.62% of the total activities respectively. The proportions of other activities are small, such as alerting, flying, standing, preening and walking. We have studied the feeding time and pecking rate of Bean Geese on Carex especially, and we found that they both keep steady when the food is enough. In middle winter, at the time of food shortage, the feeding time is still keep at a high level, but the pecking rate is decreasing. When the pecking rate decreases to a level low enough the geese will abandon the habitat and will find another source of food, such as the Trapa. In spring, the geese need to store energy for their migration to the breeding area, the feeding time and pecking rate both will increase. The geese adapt themselves to the environment by adjusting their daily activities and the pecking rate, dropping rate as well as stepping rate, and it reflects on the other side the availability of the habitat. The Bean Geese will change themselves regularly in wintering, and we use API (Abdominal Profile Index) to reflect these changes. After a long time flight, when they arrive at Shengjin Lake the API is low. In middle winter, because of food shortage, the API is low again, but before migration to the breeding area, the API is high so as for the migration flight.