Intrasexual Competition and Spacing Behaviour in Male Field voles, Microtus agrestis, under Constant Female Density and Spatial Distribution

Abstract

The influence of male density on the spacing behaviour of male field voles, Microtus agrestis, was experimentally investigated in field enclosures. Males were radio-tracked at different densities (3 or 6 males per enclosure) with the same density of females (five in each enclosure) placed in stationary cages. Male density influenced individual males' spacing behaviour. Home ranges were smaller and overlapped more, and movement activity was lower at the high male density. Furthermore, at high male density home range size varied more between individuals; small home ranges were smaller at high male density than at low density, whereas the largest home ranges were of similar size in the two experimental setups. These results suggest that at high male density competition between males increases and, consequently, less competitive males suffer from the increased competition. Finally, intrasexual competition apparently constitutes an important influence on the spacing system of male field voles