Individual variation in the duration of territory occupation by males of the dragonfly Perithemis tenera (Odonata: Libellulidae)

In the dragonßy Perithemis tenera Say, males defend territories around oviposition sites and defense of a site is critical for reproductive success. This study Þrst demonstrated that individual males variedconsistently inhow long theydefendedaparticular territorywithin aday(their “tenure”) and in the quality of the sites they defended. I then investigated a number of factors that may have affected territory tenure and may have led to the observed variation among males. Territory occupations that ended “voluntarily” were signiÞcantly longer than those that ended because themale was evicted fromhis territory. For voluntary desertions, tenure durationwas unrelated to age,wing length, the amount of time the male fought that day, or site quality. However, tenure durations were longer for males that arrived earlier in the day than for those that arrived later, and consistent differences existed among males in arrival time. Furthermore, tenure durations were longer when males had successfully mated than when they did not mate; available evidence suggests that this pattern may be because mating success causes them to stay longer. Thus, the results suggest that the problem of explaining tenure duration in P. tenera can be largely broken down into identifying factors that affect a maleÕs likelihood of being evicted and his relative arrival time. Overall, males that defended better sites and males that had longer wings were territorial for fewer total days. Of these two factors, site quality seems to have a larger effect than wing length on the number of days, suggesting that males may incur an increased cost by defending sites that are more attractive to other males.