甘南草原高原鼢鼠年龄划分及其组成分析

建立高原鼢鼠(Eospalax baileyi)种群年龄鉴定划分标准,可为对其的监测及防控提供科学依据。研究于2015年5月、10月分别在甘南草原碌曲县采用夹捕法捕捉高原鼢鼠469只(雄鼠209只,雌鼠260只),在对样本进行逐个解剖和数据记录之后,参考其体重、体长、胴体重及毛色等,对高原鼢鼠的年龄划分标准进行研究。依据胴体重将高原鼢鼠分为6组:亚成年组(雄144 g,雌106 g),成年Ⅰ组(雄144~210 g,雌106~148 g)、成年Ⅱ组(雄211~276 g,雌149~190 g)、成年Ⅲ组(雄277~342 g,雌191~232 g)、成年Ⅳ组(雄343~408 g,雌233~274 g)和老年组(雄409 g,雌275 g)。年龄结构表显示,不同的季节和不同地理区域高原鼢鼠的种群年龄结构类型均为增长型。

Age Determination and Composition Analyses of Plateau Zokor (Eospalax baileyi) in Gannan Meadow

Age estimation is of paramount importance for studying animal population ecology. The methods of age assessment may help us to determine different individual or population criteria including growth rate, age of sexual maturity, population birth rate, survival rate, age structure, etc. Furthermore, the age and its variation can largely determine the potential and size of the population, and thus form a high population size and cause the damages. The knowledge of population age structure and composition can give us the important reference for the animals management. Plateau zokor (Eospalax baileyi) is a typical subterranean rodent species inhabit the Qinghai-Tibetan Plateau. They usually dwell prairies, meadows and farm fields and form dense populations, destroy crops, compete with other livestock, and cause soil erosion. Even worse, zokors population may reach pest levels when the grasslands are overgrazed by livestock and hence they aggravate the grassland degradation. In our study, 469 plateau zokor (260 females, 209 males) were captured in Gannan meadow, Luqu County during May to October 2015. The body length, body weight, carcass weight, propagation characteristics of each individuals was recorded, and the difference between each age groups body weights, carcass weights were analyzed by using t-test. Results show that the average body weight of female and male zokors was significantly different (274.1 ± 2.7 g vs. 386.0 ± 5.7 g). Using body weight as the standard, plateau zokor can be divided into 5 natural age groups. By inter-age group differences t-test, adjacent difference between the two groups was significant (P < 0.05) (Table 1). There was no significant high correlationships between body length and body weight (Table 2). Moreover, we compared the efficiency of age determination by body weights or carcass weights, and found out that the carcass weight is the a more suitable parameter. Taking the reproductive status as a reference, we divided the female and male zokors into 5 age groups: I, II, III, IV and V (Table 3). The age determination of plateau zokor has followed a growth-oriented pattern in different areas and seasons in Luqu County (Figure 1 and Figure 2). The formula of age estimation by carcass weight obtained from the present study can be used as a reference chart in plateau zokor control strategies.