We studied the demography and territorial behaviour of three species of the dam-selfly genus Hetaerina, H. aurora, H. caja and H. fuscoguttata, along three lowland streams in western Ecuador: Tabuga, Buenaventura and Moromoro. We measured recapture rates of marked individuals and estimated survival, longevity, sex ratio and population size of the most abundant species at each location. We found male-biased sex ratios in two out of three populations and high recapture rates of H. fuscoguttata on the Tabuga river and H. aurora at the Moromoro stream. We recorded male territorial behaviour and reproductive behaviour of the three Hetaerina species by direct observation. At all study sites we recorded few reproductive events. Conversely, we registered a high number of male-male agonistic interactions confirming that all species behaved in a territorial manner. We identified three clear behavioural strategies in males: Territoriality, site fidelity and non-territoriality. However, we found no phenotypic correlates of males' strategies.