高原鼠兔种群繁殖生态的研究

STUDIES ON THE POPULATION REPRODUCTION ECOLOGY OF PLATEAU PIKA

1985—1988年,在青海湖黑马河地区以耳标法对高原鼠兔的繁殖生态进行了研究。在繁殖群体中主要是来自上年出生的第1、2胎的鼠兔(82.85％),第3胎和老体占少数。成年雌鼠兔100％参加繁殖,通常年产3胎,有的年份可产4胎或5胎。产仔数1—8只(平均为4.52±0.12),1只雌鼠兔终生可产2—29只。妊娠期为22.2±0.13天。洞内哺乳期为11.65±0.01天。有的年份当年出生的少数雌鼠兔到36.8+3.05日龄可达到性成熟并参加繁殖,生1—2胎。雄鼠兔性成熟较晚。

The studies on the reproduction ecology of Plateau pika (Ochotona curzo-niae), as a part of a five-year (1984-1988) project of the behavioural ecology of the species, have been carried out at Heimahe area during from 1985-1988. The area we surveyed is near southwestern border of Qinghai Lake, Qinghai Province. The results of our investigations are briefly mentioned as follows. The beginning and ending of breeding period as well as the number of the pregnant time on Plateau pika usually varies with years according to our firsthand observations; (see Table 1 .) . From an analysis of the data on reproduction, it may be seen that the breeding population are composed mostly of the first and second litter of Pikas born in the preceding year, occupying 57.14% and 25.71% respectively of the total number of the breeding population, while the remaining 17.15% consists of the third litter of pikas and old individuals. The range of the litter size of Plateau pika varies from one to eight young at a time, averaging 4.52+0.12. Usually three litters are produced by a female during one year, sometimes female can give birth to four or five litters. All the adult females are found to take part in reproduction. Altogether 2 -29 young may be born in the female's all life. The gestation period of the species is usually 22.2+0.13 days on an average. The suckling period in burrows where female's breast-feed their young is 11.65+0.01 days based on our observations in the field. Only a few of first litter of young born in the present year, have been found to reach sexual maturation during summer. However, there are indications that the period of sex maturity of the females is earlier than that of the males (36.8+3.05 days as against 39.6+2.6 days on average).