Abstract: The evidence indicated that the Buff-breasted rat that distributed mainly in south China and Southeast Asia is spreading to the north. Although the population density of the animal in south China is still higher than that of in north China, the population of this animal is increasing in the north China and decreasing in south China. It is suggested that the worming climate be one of the most important reasons for the spreading of the animal and the increasing of the population in north. The population of the animal decreasing in south is because of the improving of house structure.
The rats in south China inhabit both in farmer’s house and on farmland. However，the rats distributing in north China mainly inhabit in the buildings. These perhaps relate to the differences of climate between the north and the south.
The mean body weight，body length and tail length are 86.7g，142.9 mm and 157.6 mm respectively in Dongting Lake region. The body length of the animals in Dongting Lake region is generally shorter than the tail length. However, the proportion of the individuals that the tail length is shorter than the body length in Dongting Lake region is lower than that in Yunnan.
The animals breed all the year in Dongting Lake region. The breeding potential of the animal reaches the peak during April and May. The monthly mean value of rate of pregnancy and index of reproduction (litter size number of subadult + adult females) are 25. 5% and 1 .99 respectively. The mean litter size is 7. 11(range 1-17) . The monthly mean proportion of testes in scrotum is 68.0%. The animals that distribute in north China stop breeding in winter.

Key words: Buff-breasted rat (Rattus flavipectus), Morphology, Habitat, Reproduction, Population, Yangtse valley, Dongting Lake region

摘要： 黄胸鼠体型中等，在我国主要分布于南方地区，在长江流域大部分栖息于房舍及其周围。在1982-1998年间以洞庭湖区4个县为主，用夹夜法在室内和野外进行了调查。在洞庭湖区，黄胸鼠的尾长总体而言长于体长，但仍有少部分个体的尾长短于体长。洞庭湖区的黄胸鼠终年繁殖，繁殖能力夏半年高于冬半年，繁殖高峰为4-5月，冬季为繁殖低谷期。雌鼠总体怀孕率与繁殖指数分别为25.3%与1.61，各月平均分别为25.5%与1.99，最高皆出现在4-5月，胎仔数在1-17之间，夏半年平均胎仔数多于冬半年，全年为6.46，平均为7.11，每年可繁殖2-4胎；雄鼠睾丸下位率普遍夏半年高于冬半年，4-5月为最高。从南向北，黄胸鼠的繁殖高峰由双峰向单峰逐渐演变。在洞庭湖区种群数量高峰一般出现在秋季。在我国，黄胸鼠的种群有不断向北扩展的趋势。

关键词: 黄胸鼠, 形态, 栖息, 繁殖, 种群, 长江流域, 洞庭湖区