ess Factors in Local Water-Vole Population

摘要

The physiologic mechanisms of stress have multiple effects on the adaptive capacity of an individual. Thus, the analysis of factors that determine the level of stress in animals in a changing environment acquires considerable ecologic and evolutionarysignificance. The results of long-term studies performed at the site of an irrigation canal, which is annually populated by water voles, are described in this paper. A high level of stress in male water voles has been found when the resources (food andmates) are scarce. The activation of adrenocortical function under the conditions of insufficient resources occurs due to the intensification of the intraspecific competition, which takes place after a decrease in both the food supply and the ratio of females in the local population. The effects of these factors are mediated by changes in spatial and ethologic structure of a studied population appearing as an increasing overlap of individual areas. The food supply and insufficient number of females affect the levels of glucocorticoids differently in resident and nonresident males. Our results suggest that social interactions act as actual stress factors in water voles, even if a considerable decrease occurs in water vole populations, which takes placein North Baraba due to the reduction of watering in the area and the decrease in territories suitable for summer habitation.