Territoriality and Male Mating Success in the Green Frog (Rana Clamitans)

Territorial behavior of Rana clamitans was studied in an enclosed experimental pond. Males maintained territories from June through August. Most ♂ ♂ occupied more than one site during the breeding season. Most sites were occupied for < 1 wk before changing ownership, but some were occupied by a single ♂ for up to 7 wk. Large ♂ ♂ remained at individual sites longer and spent more total time in territories than small ♂ ♂. The smallest of ♂ ♂ usually acquired territories only after other ♂ ♂ had abandoned them, while larger ♂ ♂ sometimes ousted residents with aggressive behavior. Males sometimes adopted a satellite role in the territories of other ♂ ♂ and waited for sites to become available. Individual territory sites were ranked by relative quality based on the physical structure of the sites. Female choice of mates appearerd to be related to territory quality, and especially to density of vegetation in the water. Males that spent the most time in high quality territories acquired the largest number of mates. The social system of the green frog probably evolved as a result of intense ♂— ♂ competition for mates. This in turns is probably related to its prolonged summer breeding season.