Multiple morphological characters needed for field identification of cryptic long-eared bat species around the Swiss Alps

The identification of cryptic species may significantly change our view about their distribution, abundance, ecology and therefore conservation status. In the European Alps, molecular studies have revealed the existence of three sibling species of plecotine bats Plecotus auritus, Plecotus austriacus and, very recently, Plecotus macrobullaris. Knowledge of the ecological niche partitioning of cryptic species is a requisite to develop sound conservation policies. Yet, this requests the development of unambiguous identification methods easily applicable in the field. This study investigates the reliability of several morphological methods used for species recognition and proposes a new identification key for field workers. We captured 214 Plecotus bats from 29 sites in four bioregions within Switzerland, collected biopsy punches for genetic analysis, described and measured external morphological characters. All three species occurred as mono-specific colonies, except at one site where P. auritus and P. macrobullaris shared the same church attic. Qualitative traits alone did not allow a reliable separation of the three species. A series of multivariate analyses conducted on external linear measurements resulted in a discriminant function enabling correct species classification with a 97.5% probability. Compared with genetic analysis, our multivariate morphological method represents a valuable, rapid and cost-effective alternative.