Responses of the endangered pygmy bluetongue lizard to conspecific scats

Abstract

Many animals use chemical signals for communication between conspecifics and for territory marking. The pygmy bluetongue lizard is normally solitary, focussing activity around the entrance of its burrow, from where it ambushes prey, and rarely contacts other individuals. In this paper we examined whether lizards in laboratory experiments alter their behaviour in the presence of scats from conspecifics. In the first experiment, when lizards were offered a choice of two vacant burrows with or without a scat close to the entrance, they tongue flicked more often at the burrow entrance when the scat was present, and more often chose to occupy the burrow with the scat. An interpretation is that lizards use scat signals to recognise burrows that may be suitable because they have previously been occupied by a conspecific, but that they approach those burrows cautiously in case a resident is still present and likely to resist a takeover. Scats from male lizards were inspected (by both sexes) for longer than scats of female lizards. In the second experiment, when resident lizards were presented with scats outside of their burrows, they inspected and tongue flicked at those scats more often if the scat came from a male than a female lizard, but there was no definitive evidence from our experiments that lizards differentiated in their response to scats from lizards that were found close to or far from the test lizard. The results were consistent with a communication system in which lizards use scats to advertise their presence, independent of any direct contact.