Study on population age of Tscherskia triton in Shunyi district, Beijing.

Objective To indentified the population age of Tscherskia triton scientifically and easily, and to grasp its population age structure so as so increase the prediction level of rodent infestation. Methods The investigations were carried out from early March to early October every year by night trap method during 1994-2006 and 400 clamps were used every time. Some indexes of the captured samples, including body weight, body length, tail length, auricular height and hindfoot length, were measured. The samples were dissected to investigate the reproduction situation. The age of T.triton was identified by mathematical statistics method based on the body weight and its reproductive characteristics. Results A total of 2176 samples captured were divided into five age groups according to the body weight and reproductive characters. They were the young group (Ⅰ, female: less than 35 g. male: less than 33 g), sub-adult group (Ⅱ, female: 35.1-75 g. male: 33.1-79 g), adult groupⅠ(Ⅲ, female: 75.1-121 g. male: 79.1-123 g), adult group Ⅱ(Ⅳ, female: 121.1-185 g. male: 123.1-187 g) and older group (Ⅴ, female: more than 185 g. male: more than 187 g). Conclusion The results showed that it was very convenient to take body weight as the division standard of T.triton. There was a significant difference among five age groups. The weight increased with the increase of population age. The reproductive capacity was significantly different among different age group, which rose with the increase of age. Sub-adult group and adult groupⅠtook absolute advantage in the population structure.