Trophic niche and diet composition of the northernmost population of the Mediterranean horseshoe bat (Rhinolophus euryale) with conservation implications
Abstract
The diet of Rhinolophus euryale was studied in southeastern Slovakia by an analysis of faeces collected from netted bats. Prey availability was studied using light traps, counting flying insects on the transect, and sweeping the vegetation.
The diet composition was dominated by Lepidoptera, especially in July and September, which corresponds with most diet analyses reporting the species as a Lepidopteran specialist. Nonflying arthropods were almost absent from the diet, suggesting that the species obtains most of its food mainly by aerial hawking.
The spring diet showed unusually high volumes of Diptera; this differed significantly from the evidence from its core distribution area in the Mediterranean. This suggests a higher flexibility of the trophic niche in the marginal parts of the species range.
Our results suggest sex differences in diet. Possible conservation measures for these marginal populations should consider the protection of diverse mosaic landscapes, including urbanised patches.
Such areas with long, warm interfaces of open and bushy and/or forest habitats have high moth flying activity, and riparian patches provide dipteran prey in spring when moths are scarce. The prediction of the prosperity of the studied northernmost populations of R. euryale during the ongoing climate change is ambiguous since various conceivable scenarios could work: (i) good prosperity of the population thanks to a warmer climate, higher production and higher flying activity of prey, or (ii) a worse situation due to unevenly distributed precipitation and higher evaporation, which may negatively affect wet habitats providing the important spring diet of tipulid dipterans.