PHENOLOGY OF THE REGIONALLY CRITICALLY ENDANGERED DRAGONFLY UROTHEMIS EDWARDSII IN THE NATIONAL PARK OF EL KALA, NORTHEAST OF ALGERIA

In the Mediterranean, Urothemis edwardsii is one of the most threatened dragonfly species with a relict population restricted to the northeast of Algeria. Despite the recent subtle local expansion in the geographic distribution of the species during the past decade, studies on the life history of the species are still lacking. We carried out a study on the phenology of emergence and flight season on Lake Bleu, Northeast-Algeria. Using repeated sampling of exuviae and marking of adults during two seasons (2018 and 2019), we estimated the population size, sex ratio, and the temporal pattern of emergence and flight season. The first year (2018) was considerably drier than the second year (2019). We collected a total of 576 and 887 exuviae and 711 and 655 adults in 2018 and 2019, respectively. The sex ratio at emergence was slightly female-biased with 57.1% in the first year and equal to unity (50.5%) in the second year, respectively. The species started its emergence earlier in the dry year (2018). The emergence of the species was quite asynchronous where 50% of the population emerged after 11 days and 16 days in 2018 and 2019, respectively. The difference in population size (based on exuviae) and the temporal pattern of emergence and flight season were likely due to differences in weather between the two years. The current study provides useful information on the life history and plasticity of U. edwardsii, which could be used for the management of this locally Critically Endangered dragonfly.