1. In Great Britain the distribution of the riverine damselfly Calopteryx splendens is predominantly southern. However, the last decade has seen records of the species in previously unoccupied areas in the northeast of England, prompting speculation regarding northward range expansion. The current study is the first to quantify the physical features of the habitat that influence the presence of C. splendens.
2. A field survey was carried out on the physical characteristics of habitat supporting C. splendens along a section of the River Wharfe, West Yorkshire, U.K. Adult C. splendens were marked uniquely for individual identification in order to assess the occurrence of the species within different habitat patches of the study area.
3. A multiple logistic regression was used to identify the significant habitat variables in explaining the occurrence of adult C. splendens.
4. The most important habitat factor in determining the presence of C. splendens was the height of the vegetation at the edge of the river. Significant negative relationships were found between the presence of C. splendens and tree coverage along the bank, and between its presence and increased bank height.
5. The distribution of C. splendens is affected by the natural physical features of the habitat, anthropogenic disturbance and the behaviour of the species itself.
6. The importance of quantitative habitat data in species conservation, particularly with regard to range expansion, is discussed.
1. Flight activity in zygopterans is generally restricted to short-range movements associated with foraging, reproductive activity and escape. Indeed, previous studies have suggested that Calopteryx species, including C. splendens, are relatively sedentary species, with a low tendency for long distance movements.
2. Recent observations suggest that C. splendens is expanding its northern range in the UK; in the northeast the species is now well established in Northumberland and, in the northwest, has recently spread into south-west Scotland. The current study aimed to investigate the mobility and dispersal tendency of C. splendens in a well-established breeding population in NE England.
3. A mark-release-recapture study was carried out on a population of C. splendens along a section of the River Wharfe, West Yorkshire, UK. 831 adult C. splendens were marked uniquely for individual identification in order to monitor the day-to-day, and overall, distance and direction of movement for each individual. Of these 381 were recaptured at least once.
4. The majority of males (85%) and females (88%) moved a distance of 100 m or less and only five of the recaptured individuals (1.3%) moved a minimum distance in excess of 500 m. Although the median distance moved by males was greater than that for females, this was not significant. In addition, there was no significant difference in the number of either males or females moving upstream as opposed to downstream.
5. The results are compared with those from other studies on calopterygid movement. Although most individual C. splendens stay within a suggested home range of approximately 300 m, clearly individuals have the potential to cover relatively long distances, and it is these latter movements that play a fundamental role in increasing the range of the species.