Sex-specific spatial patterns in the threatened damselfly Coenagrion ornatum: implications for the species' conservation and monitoring
Abstrakt
The damselfly Coenagrion ornatum is a threatened species, specialized for lowland headwater streams. As the species is declining and protected across Europe, it represents a species of particular conservation interest.
This work aims to provide the first evaluation of fine-scale spatial ecology in this species, especially to assess its general mobility and distribution of adults in relation to larval habitats, and to suggest implications for conservation and efficient monitoring of this species. Adults were captured-recaptured along four distinct streams (5.2 km together) in the Radovesická spoil heap, Czech Republic.
Immature adults and breeding individuals were recorded simultaneously. Larvae were sampled in 64 sections of 27 m, evenly distributed across the studied streams.
In total, 1152 adult individuals were marked; from these, 240 individuals were recaptured at least once. Larvae were detected in 21 sites with a total number of 61 individuals.
The adults were highly sedentary, with a median lifetime dispersal of 11 m. Only one male was reported to move between two distinct streams.
Model comparisons revealed that female and breeding pair abundances are a significantly more reliable indicator of larval abundance than male and total adult abundances, especially when used along with records of the immature adults. Moreover, the weighted least square models showed that the female abundances are spatially more specific (i.e., less autocorrelated) than male abundances.
These results imply that surveying the adult females, along with the breeding and immature adults, offers the best method for local habitat quality assessment for this Natura 2000 species.