A mark-recapture study of coexisting zygopteran populations

An analysis is presented of the coexistence of 8 spring spp. in an area in Eastern Flanders, Belgium. By counting exuviae and by the mark-recapture method, the behaviour of the different spp. in space and time was followed. The data include estimates of the translocation within the area and estimates of population size and survival rate using the method of Jolly and Seber and a new regression method. – Between spp. (of different genera), differences in spatial and temporal performance were noted which result in a reduction of interaction, whether or not truly competitive. However, between the coexisting sibling spp,, Coenagrion puella and C. pulchellum, no major differences in utilisation of the environment could be found. There are indications that 99 of C. puella were driven out of their favored areas, but inspite of this they continued to oviposit at the peak density of C. puichellum. This observation leads to a reconsideration of the competitive exclusion principle.