ON THE POPULATION DYNAMICS AND REGULATION OF MERIONES UNGUICULATUS IN AGRICULTURAL REGION NORTH TO YIN MOUNTAINS, INNER MONGOLIA

Abstract

The population dynamics of the gerbil, Meriortes unguiculatus Milne- Edwards was studied in the years 1964-69, at Siziwangqi,Inner Mongolia, where the agriculture has a representative characteristics in the region North to Yin Mountains. A strip area of 7-9 Km. in length was investigated annually in April, June and September and more than 1800 gerbils were captured. Their reproductive status and measurements were recorded, and their skulls were preserved for further studies. From the biological points of view, in studying the population dynamics of the gerbil, we have recognized the following 4 points: 1) There were larger variations in age structure, body length, body weight etc. of the populations in different years. 2) The percentage of the males with enlared seminal vesicle in the same season of different years had an inverse relation with the population densities. 3)There was a positive correlation between the reproductive indices of the females and the density increments of next year. Besides, a positive correlation also existed between the spring reproductive indices and the summer density increments in multiples. 4) Reproductive phenomenon existed in winter, but it changed greatly in different years. A non-reproductive period existed in August-September. The environmental factors influencing the population such as the climates and agricultural measures were also considered.