Telemetry reveals the habitat selected by immature dragonflies: implications for conservation of the threatened dragonfly Leucorrhinia caudalis (Odonata: Anisoptera)

Abstract

Determining how species use different habitats during critical phases of their development is one of the crucial challenges that conservation biology meets. However, habitat requirements remain unknown for most species, in particular for the rarest and most threatened which by definition are difficult to study. Here, we used animal-borne telemetry to identify the habitat of the sexually immature adults in the threatened dragonfly Leucorrhinia caudalis. We used an harmonic radar with customized tags fixed on the back of the abdomen of flying immature dragonflies to monitor their position within an area composed of various types of habitats including open areas, forest and water bodies. From 62 tagged individuals, we obtained 23 detections, all within a quite restricted area around the pond of emergence. About 75% of the detections happened in the forest canopy and the individuals were likely positioned at the top of the trees. The relatively low detection rate was probably due to high predation within the study area during the maturation phase in this dragonfly but long-range dispersal cannot be excluded. The use of forest canopy as a maturation habitat is an important knowledge for planning conservation strategies in this endangered species, especially for populations living in areas without any protection status. Although technological constraints are still limiting its efficiency, animal-borne telemetry appears to be useful to determine precisely habitat selection by rare species.