The use of scats as social signals in a solitary, endangered scincid lizard, Tiliqua adelaidensis

Context. The deliberate accumulation of faeces or scats in one location is a common behaviour used for social signalling. The endangered pygmy bluetongue lizard, Tiliqua adelaidensis, is a solitary-living species that appears to use scats as social signals. Previous studies have found that these lizards approach burrows more cautiously if there is a conspecific scat present and behave differently to scats from male and female conspecifics, indicating that these lizards can recognise scat-based conspecific cues. For endangered species, understanding how an animal uses and responds to chemical cues has the potential to become a powerful tool in conservation management. Aims. To investigate whether these solitary lizards might be using scats as social signals by testing whether scats were being deposited in a non-random pattern designed to maximise their exposure to the nearest neighbour conspecifics. Method. In the present study, we investigated the spatial pattern of scatting behaviour by pygmy bluetongue lizards in the field. Results. Scats were consistently deposited in one direction that was significantly aligned with the nearest occupied burrow of a neighbouring lizard. The same deposition sites were used when previous scats were either destroyed by rain, or experimentally moved to a different location. Male lizards deposited scats significantly closer to their own burrows when neighbours were closer. Key conclusions. The results were consistent with the lizards using scats to advertise their presence and status. The scat-deposition patterns observed in the present study suggest that scats are used as an olfactory signal associated with social organisation of pygmy bluetongue lizards. Implications. Current plans for the conservation management of this endangered species include translocations. By understanding how these lizards respond to, and use chemical cues, we may be able to use this knowledge to aid in translocation programs, e.g. by pre-establishing territories for individuals before they are introduced into the population.