Resources and their distribution can influence social behaviour at translocation sites: lessons from a lizard

Abstract

In a translocation programme, social interactions among released individuals can influence the tendency for the individuals to remain at the site where they have been released. Dispersal away from the region of release may reduce the success of a translocation because dispersing individuals may move into less suitable habitat, or become separated from potential reproductive partners. In soft releases, where individuals are confined together for periods of time at the release site, before ultimate release, social interactions among the confined individuals may promote subsequent dispersal. In this study we investigated how variation in the abundance and distribution of a fundamental habitat resource, refuge burrows, influenced behaviour and possible subsequent dispersal of newly released individuals of the endangered Australian pygmy bluetongue lizard, Tiliqua adelaidensis, in simulations of translocation releases. Our aim was to determine if there was an optimal distribution of burrow resources that would minimise behaviours likely to lead to dispersal from the release site. There were more lizard movement around burrows 3.73 (SE 0.02) and fewer burrow changes 0.06 (SE 0.006) in low burrow densities than in high burrow densities (1.88 (SE0.02) movements; 0.50 (SE 0.008) burrow changes per day). When lizards were released in burrows near to each other (50 cm) they changed burrows more often (0.97 (SE 0.01)) and had more agonistic interactions (0.04 (SE 0.004)) than when released in burrows further apart (150 cm; 0.22 (SE 0.009) burrow changes; 0.003 (SE 0.001) agonistic interactions). These results suggest changes in behaviour can be induced by altering the way resources are distributed at a release site. We suggest that understanding the social organisation of any endangered species, and whether it can be manipulated, will be an important component of planning a translocation release programme.