Faecal pellets used as an economic territorial marker in two terrestrial alpine salamanders

Abstract

Scent marking is often related to activities associated with the occupation of a home range or territory. It is widely agreed that when an animal sends signals, this influences the decisions made by the animal that receives them. Scent marks are mainly used as a warning, in order to decrease the cost of territorial behaviour. They are deposited directly on a substrate by rubbing them on but also through urination and defecation. European terrestrial salamanders show high site fidelity and move very little around their shelter. Risks and costs are compared before an animal decides whether or not to leave its shelter, and a rapidly detectable and unambiguous cue in the direction of the home shelter reduces risk. Furthermore, territoriality has also been observed in amphibians, both in Anurans (frogs and toads) and Urodela (newts and salamanders). We tested the use of faecal pellets in alpine salamanders in the laboratory (Salamandra lanzai and Salamandra atra) with regard to homing and territorial behaviour. Our experimental design allowed us to distinguish attraction to from avoidance of shelters containing varying olfactory information. Our results clearly argue for the role faecal pellets play in shelter recognition. Furthermore, contrary to the results observed in other terrestrial salamanders such as Plethodontids, the faecal pellets of S. lanzai and S. atra enable intruders to identify the residents, thus fulfilling the requirements of a genuine territorial warning, as observed in mammals. Excrement marking is used as an economic tactic to identify and warn about the occupation of a territory in these two species of alpine salamanders.