We studied a population of Polythore procera along a stream in the Colombian eastern Andean foothills.Mark and recapture samples were made during January to April 2006, covering both dry and wet seasons.We determined population size, daily survival probability, and longevity during the entire period and compared them with precipitation data.Age and sex proportions along two different sectors of the stream were also analyzed, and notes about their ecology and habitat were taken.Our data suggest this species has a high daily survival probability in comparison with those of other odonates.Males are highly territorial, and exhibit low dispersal capacity.We also conclude that population dynamics of P. procera can be affected by an extrinsic factor such as seasonality.