Empleo de excrementos de nutria Lutra lutra (Linnaeus, 1758) para la diagnosis específica de los cangrejos de río en la Península Ibérica

The Eurasian Otter (Lutra lutra) is a semiaquatic carnivore usually feeding on a wide spectrum of prey items. Otter diet is commonly determined from non-digested fragments found in their spraints, or within prey remains deposited along the rivers where they live. Three crayfish species occur within the Iberian Peninsula, one being native and suffering a severe risk of extinction, and two being invasive species originating from North America. In mountain areas, where a total or partial drought in a number of streams and creeks is common, crayfish often become an important dietary resource for otters. Nevertheless, many of the papers dealing with crayfish as a prey item for this mustelid do not identify the species involved. The present work makes an attempt to define some morphological traits observed in crayfish fragments found in spraints or partially consumed remains from otters inhabiting the southern Iberian Ridge, which could serve to identify a crayfish species in a quick and simple way. Furthermore, these features can help in locating and identifying new crayfish populations while carrying out otter surveys, and vice versa