The value of terrestrial ecotones as refuges for winter damselflies (Odonata: Lestidae)

Abstract

Habitat requirements of many species may vary significantly throughout the lifecycle. Species are often forced to exchange their habitats to meet requirements of different life stages. Due to the effect of human activities, however, there is a loss of habitat complexity and a consequent disappearance of species associated with multiple habitat types. This also applies to freshwater invertebrates occurring in temporary habitats. However, it appears that many species are able to meet their habitat requirements even in a human-altered landscape. The aim of this study was to analyze the habitat preferences of the damselfly Sympecma fusca in an area significantly influenced by human interventions. According to the results of a capture-mark-recapture study and generalized additive models, I found that, during a pre-reproductive period (in the autumn), imagoes utilize predominantly insolated ecotones, which constitute only a small fraction of the available terrestrial habitat. During the reproductive period (in spring), however, imagoes completely change their priorities in favor of reproductive success. At this time, males use ecotones only in adverse weather conditions. Ecotones allow the species to survive a long pre-reproductive period. However, suitable habitat conditions may be lost because of inappropriate interventions (e.g., mowing). These small-scale interventions often resemble natural disturbances and may not necessarily lead to the extinction of an entire population. Imagoes are able to move on to different habitat patches, but only if they have alternative habitats. This outcome indicates that maintaining a high heterogeneity of keystone structures is crucial for maintaining high levels of biodiversity.