关键词: 高原鼠兔, 种群密度, 类固醇激素

Abstract: This research investigated differences in population increases, plasma concentrations of four steroid hormones, and paired adrenal masses of plateau pika (Ochotona curzoniae) at different population densities under field conditions in 2003,to test the relationship between population density and endocrine level. Population density increased the most the in population with the highest density. In contrast, the population with the lowest density increased the least. There were some differences significant in plasma corticosterone levels and adrenal masses between or among population densities. Furthermore, throughout the reproductive period, the variation patterns of corticosterone levels and adrenal masses were different between higher and lower density populations. This change was more obvious in the higher density population than in the lower density population. However, there were no significant differences in the estradiol, testosterone and cortisol levels between or among population densities, and the different seasonal patterns were not observed. We concluded an intense social stress was not elicited by the high population density, and subsequently limited the population increase of plateau pika in the current nature with a low population density.

Key words: Plateau pika (Ochotona curzoniae), Population density, Steroid hormone