The effects of weather conditions on dispersal behaviour of free-ranging lizards ( Tiliqua, Scincidae) in tropical Australia.

Animals may switch between alternative modes of movement (e.g. philopatry vs. dispersal) in response to complex interactions between internal state, landscape characteristics, dispersal capacity and navigational capacity., In this study, we use an extensive data set from GPS telemetry of free-ranging lizards (bluetongue skinks, Tiliqua spp.) in the Australian wet-dry tropics, to examine how abiotic conditions (temperature, air pressure, precipitation, humidity and wind speed) influence lizard dispersal. The GPS transmitters provided >60,000 records of lizard location from 49 individuals (41 T. scincoides intermedia, 8 T. multifasciata) monitored for a mean of 65 days each., We used a maximum likelihood analytical tool to objectively distinguish intra-patch movements from dispersive movements. Threshold levels of dispersal to differentiate between these two movement phases averaged 36-42 m displacement per hour, depending on species and site., Whether bluetongue lizards within the study population dispersed (rather than remained encamped) was highly associated with weather variables, notably air temperature and atmospheric pressure. Fine-scale (hourly) weather conditions were better predictors of lizard dispersal than daily mean values., Lizards primarily dispersed between widely scattered patches of core-habitat under fine, hot, clear weather conditions. Air pressure tended to predict lizard dispersal more accurately than did more commonly analysed variables such as temperature and precipitation. [ABSTRACT FROM AUTHOR]