关键词: 长爪沙鼠, 胴体重, 肥满度, 年龄, 季节

Abstract: Relative fatness is an important general indicator of physiological body condition of small mammals and reflects their adaptive ability to the environment. The relative fatness of Mongolian gerbils ( Meriones unguiculatus) was studied from March to November 1997 in TaiPuSi Banner, Inner Mongolian in China. It was calculated by the formula : K′= 100W_N/L³ (g/cm³ ), where L indicated the naso-anal length , and W_N was the carcass body weight minus all internal organs. The removal of all internal organs is to exclude the possible ones caused by the weight of food in digestive canal , embryos or pregnancy and sexual organs. Results indicated that the relative fatness changed significantly with age which relative fatness of sub-adult individuals was significantly higher than that of adult ones. Its seasonal changes of different sexual age groups were in accordance with this rule : relative fatness of rodents becomes high in spring , lowest in summer and fatted again in autumn in high altitude zones. Our results indicated that the relative fatness of the female was higher than that of the male before August ; and the relative fatness of the sub-adult and adult male groups were fatted until September or October , while that of the female group fatted until November. Combined with the life-history characteristics , it was concluded that Mongolian gerbils adjusted its hysiological conditions to adapt to the environment in different life stages. In addition , the monthly relative fatness in males negatively correlated to its monthly population relative size , and relative fatness in the adults had a significant positive correlation with the population size 4-month later. Our results indicated that using relative fatness as an indicator in forecasting relative size of population in Mongolian gerbils has its reference value.

Key words: Mongolian gerbil (Meriones unguiculatus), Carcass body mass, Relative fatness, Age, Season