Some Ecological Factors Influencing a Community of Adult Odonata

Abstract

A community of adult Odonata, composed of 18 species, was studied during June and July of 1968 at a small pond in piedmont North Carolina. Studies were made on the influences of time of day, ambient temperature, and light intensity on flight activity, and on the frequencies of intra— and inter—specific interactions. Most species initiated their flying periods by mid—day and terminated them by 1930 hr with considerable variations among the species. Maximum reproductive behavior occurred near the mid—point of the patrolling period. Minimal temperature thresholds for activity ranged from 20—28°C, whereas maximal thermal thresholds were from 30—40°C. Adult activity decreased proportionally to a decrease in light intensity during cloudy periods or thunderstorms. Activity of individuals to some species was controlled chiefly by one environmental factor, but in others activity presumably was related to a combination of several factors. Intraspecific interactions, usually between males, were much more common than interspecific interactions. Threat behavior was far more prevalent than actual physical contact.