Constructing burrows is energetically expensive, yet is a common trait across a broad spectrum of animals. The benefits of using burrows must therefore outweigh the costs of constructing burrows, which may reduce the risk of predation and/or ease the need for active thermoregulation. We examined the use of burrows in Butterfly Lizards ( Leiolepis belliana ), a common Southeast Asian lizard that constructs burrows in open, sandy plains. We used radiotelemetry to track the activity patterns and measured the thermal environment of 12 individuals across 14 d of sampling. We found that L. belliana had high site fidelity, using the same burrows across the sampling period. There were significant differences between substrate temperatures inside and outside the burrow across the whole sampling period. However, the lower internal burrow temperature still exceeded the upper thermal tolerance of a similar sized lizard species during midday, and this probably explains why we did not observe lizards in their burrows during the middle of the day. Burrows were constructed in a shallow, Y-shaped, concave shape, with each of the three branches of the Y ending in a surface opening, a design that allows for easy escape if threatened by a predator. Due to burrow temperatures exceeding lethal body temperatures for much of the day, and the Y-shape structure of the burrows, we propose that the major function of burrows for this species is as a predator escape mechanism.

Understanding why turtles select specific localities to nest over others is important for management and conservation. For some species of freshwater turtle, the same localities are selected year upon year, but it is uncertain whether these localities are selected due to favored environmental conditions, or natal-site homing. The Mary River Turtle ( Elusor macrurus ) is an endangered freshwater species from Australia, and nesting data gathered between 2004 and 2011 demonstrated that female E. macrurus select to nest in specific localities along the Mary River. Here, we used time-lapse infrared photography and image-identification analysis to assess whether the same individuals returned to the same nesting banks over three consecutive years (nest-site fidelity), and we compared the physical and soil characteristics of nesting areas against other localities along the river where the turtles were not recorded to nest. The photography study illustrated that some females returned to nest at the same locality over consecutive years, whereas others did not; therefore, it is still inconclusive whether E. macrurus exhibits true nest-site fidelity. Preferred nesting areas were all northerly facing and thus exposed to higher levels of solar radiation than nonpreferred areas with similar soil and physical characteristics. Consequently, the preferred nesting areas exhibited significantly greater mean and daily fluctuations in the nest temperature compared with other areas with dummy nests. We suggest that the warmer nest temperature would speed up embryo development; therefore, female E. macrurus select to nest on northerly facing banks in an attempt to reduce the embryo incubation period. A possible reason for this behavior may be to reduce their exposure to nest-raiding predators. The study highlights importance of key nesting areas along the Mary River for the conservation of E. macrurus .