Use of multiple habitat types with asymmetric dispersal affects patch occupancy of the damselfly Indolestes peregrinus in a fragmented landscape

Abstract

To appropriately predict the patch occupancy of animals, it is often essential to consider not only the habitat structure but also shifts in the habitat requirements of animals with changes in life stage. In addition, asymmetric dispersal among different types of habitat patches is likely to accompany use of multiple habitat types due to differences in the ease with which migrants can find the habitats, to changes in the dispersal ability of animals according to their life stage, or to both factors. However, few studies have explicitly elucidated the contribution of these processes to patch connectivity and to predictions of patterns of patch occupancy. In the present study, we evaluated the effects of multi-type habitat use on patch connectivity of the damselfly Indolestes peregrinus. After emergence, adults of this species move from their native ponds to woodlands for hibernation and return to aquatic habitats for oviposition in the next spring. We recorded the occurrence of I. peregrinus at newly created artificial ponds and attempted to explain patch occupancy using a series of Bayesian statistical models, which incorporate (1) local environment only, (2) both local environment and single-type habitat use connectivity, and (3) both local environment and multi-type habitat use connectivity. In addition, we considered two situations in the third model: symmetric or asymmetric dispersal. Comparing the performance of the candidate models revealed that the best model was the third model assuming asymmetric dispersal and it explained 18.8% of the deviance. The result suggests that multi-type habitat use is important for determining patch connectivity of I. peregrinus, and that there is asymmetry in the connectivity from pond to woodland patches and vice versa for the damselfly. Both multi-type habitat use and asymmetric dispersal processes are likely to apply to many other taxa and landscapes.