Territorial conflicts in males of the dragonfly, Orthetrum japonicum japonicum (Odonata: Libellulidae): The role of body size

The relationship between body size and the results of territorial conflicts was studied in males of the dragonfly, Orthetrum japonicum japonicum. Territorial residents were larger than intruders in body width, but not in hind wing length. Winners of territorial conflicts were larger than losers in body width, but not in hind wing length. This difference was attributed to the fact that residents were larger than intruders. The results of territorial conflicts were more strongly affected by the role of the opponents (resident or intruder) than by the difference in their body sizes. Territorial males arrived at the territorial sites earlier than non-territorial ones on a given day. The body size of males arriving at the study area earlier in a day was not larger than that of males arriving later.