Home – Home – Jornals – Contemporary Problems of Ecology 1999 number 1

The number of wounds on skin, social ranks of captured adult males in experimental encounters, and spatial distribution of breeding individuals were studied in a population of Arvicola terrestris (L.) during two consecutive cycles (1980-1998). The study was performed within a period of intense breeding (May and June). The level of wounding of over wintered females low and independent of population density. In over wintered males, the wounding level was positively correlated with population density. The local density of reproductively active water voles within local populations did not change regardless of population fluctuations. The nearest neighbour analysis indicated that breeding females were territorial. In the male-biased local populations, heavier males were trapped closer to females. This might reflect their advantage in male-male competition and prior access to the relatively limited reproductive resource. Male body weight significantly differed among social ranks; it was maximal in dominant individuals. Dominance capacities of homozygous brown and black, and heterozygous dark-brown over-wintered males were also compared in experimental encounters. Differences among coat colour morphs were found to be cycle-dependent. At the peak and decline phases, the percentage of dominants was higher for heterozygous dark-brown than homozygous brown males. These differences may account partly for maintenance of coat colour polymorphism within the population.