洞庭湖区东方田鼠洞群成员分析

通过对洞庭湖区不同栖息地东方田鼠洞群结构分析，结合洞庭湖区的特定生态条件，对东方田鼠在不同繁殖期的栖息习性及其适应意义进行了分析和讨论。洞庭湖区东方田鼠的最适栖息地是洲滩，但洞庭湖湖水季节性涨落，迫使东方田鼠在洲滩与垸内农田间迁移。当东方田鼠栖息在洲滩时（10－5月），即繁殖盛期，雌雄分居，雌性单独抚养后代。当迁入垸内农田后（6－9月），东方田鼠营混居生活。洲滩为其理想栖息地，单个雌鼠可以正常抚养后代，分居则有利于最大限度地提高其适合度。迁入垸内后混居可减少对空间资源的需求。从野外和室内观察情况分析，东方田鼠在繁殖盛期的婚配制度以一雄一雌的可能性很小。

ANALYSIS ON THE COLONY STRUCTURE OF MICROTUS FORTIS IN DIFFERENT BREEDING SEASON IN DONGTING LAKE REGION

The seasonal changes of Dongting Lakes' water level force M fortis move between the lake beach and the rice fields The animals inhabit on the lake beach in the main breeding season, from October to May The animals nest individually during this stage However, the aggression of the animals reduce and nest very closely when they inhabit on the rice fields in summer These changes adapt the environment of Dongting Lake region The lake beach, less interspecific competition, less predators and good food resource, is suitable for the animals Therefore, when the animals inhabit on the lake beach, the males move for finding females, and females mate with several males and rear young alone, could maximize their breeding success Because of the frequent activities of humans, interspecific competitions, predator activities and relative narrow habitat, survival is the main problem for the animals when they inhabit in the rice fields To nest closely at this stage could reduce the demand of habitat According to the observation both from fields and laboratory, we consider that there is less possibility of monogamy for the animals in main breeding season