Effects Of Natural Enemy Odors On Fecal Steroids Of Plateau Pikas

Using plateau pikas as experimental animal, the fecal of natural enemies(including cats, Tibetan dogs, weasels and plateaus zokor) as odor source, the effects of natural enemy odors on fecal steroids of plateau pikas were investigated in a laboratory feeding experiment. The main results are as follows: 1. The fecal odors of enemies had different effects on fecal corticosterone and cortisol of male pika. Compared with controls, the fecal odors of cats, Tibetan dogs and yellow weasels had significant facilitation effects on fecal corticosterone of male plateau piksa, the fecal odors of plateau zokor, however, had no effect on fecal corticosterone. The effects order are as follow: yellow weasel > cat > Tibetan dog > plateaus zokor. Likewise, fecal odors of different enemies also had significantly effects on cortisol, and the intensity changes are similar to that of corticosterone. Morepver, fecal odors of all enemies had remarkable inhibiting effect on fecal testosterone levels of male pika. 2. The fecal odors of enemies had different effects on fecal corticosterone and cortisol of female pika. In the enfluencing of cats, Tibetan dogs, yellow weasels and plateau zokor, fecal corticosterone and cortisol of female pika increased significantly. The effect intensity ranged as follows: yellow weasel > cat > Tibetan dog > plateaus zokor. In contrast with this, affected by the fecal odors of natural enemy, the progesterone level of female pika decreased significantly. The decline order are yellow weasel > cat > Tibetan dog > plateaus zokor. 3. The fecal odors of different enemies had significant effects on body weight of male and female pikas. Compared with controls, under the affecting of fecal odors of cats, Tibetan dogs, yellow weasels and plateau zokor, body weight of both male and female pika decreased significanlty. The reducing amount of male pika corresponging to cats, Tibetan dogs, yellow weasels and plateau zokor was 6.37%, 5.73%, 7.10% and 3.18% respectively;while that of female pika was 7.75%, 7.71%, 7.75% and 3.52% respectively. 4. The corticosterone concentrations of male pika were positively correlated with treating time of fecal odors of cats, Tibetan dogs and yellow weasels, while no correlations with that of plateau zokor. The cortisol concentration also had positive correlations with fecal odors of cats, Tibetan dogs, yellow weasels, and plateau zokor. The testosterone levels, however, had negetive correlations with all kinds of fecal odors. 5. The corticosterone concentrations of female pika were unimodal correlated with treating time of fecal odors of cats, Tibetan dogs, yellow weasels and plateau zoko. The correlations between cortisol level and treating time were significantly positive. The progesterone concentration of female pikas, however, negatively correlated with treating time of fecal odors. 6. The relationships between body weight of male pikas and treating time of fecal odors of cats, Tibetan dogs, yellow weasels and plateau zoko were unimodal. Similarly, the relationship between body weight of female pikas and treating time of fecal odors of cats, Tibetan dogs, yellow weasels and plateau zoko were also unimodal.