Social and Thermal Cues Influence Nest-site Selection in a Nocturnal Gecko, Oedura lesueurii David A. Pike*, Jonathan K. Webb* & Robin M. Andrews  * School of Biological Sciences A08, University of Sydney, NSW, Australia  Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA Introduction In egg-laying species, females can influence egg survival, offspring phenotype, and fitness through nest-site selection (Resetarits 1996; Shine & Harlow 1996; Blouin-Demers et al. 2004; Brown & Shine 2004; Rudolf & Ro ¨ del 2005). Females should therefore select the best oviposition sites available (Jaenike 1978; Martin 1998). However, in many taxa, multiple females often lay their eggs communally, suggesting that maternal oviposition behavior is not solely depen- dent on nest-site quality but can be influenced by social facilitation (Jamieson 1995; Brown & Shine 2005; Radder & Shine 2007; Refsnider et al. 2010), risk of predation upon the reproducing adult (Martin 1998; Spencer 2002), or a limited availability of suit- able egg-laying sites (Rand & Dugan 1983; Blouin-De- mers et al. 2004). Communal egg-laying is very common in reptiles (known in >480 species: Doody et al. 2009), and this behavior often reflects active maternal preference rather than being an accidental by-product of limited nest-site availability (Brown & Shine 2005; Radder & Shine 2007). For example, in some scincid lizards (Radder & Shine 2007), colubrid snakes (Plummer 1981; Brown & Shine 2005), and frogs (e.g., Howard 1980), mothers are attracted to nest sites used by other females, even when suitable alternative nest Correspondence David A. Pike, School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia. E-mail: david.pike22@gmail.com Received: March 24, 2011 Initial acceptance: June 6, 2011 Final acceptance: June 11, 2011 (J. Wright) doi: 10.1111/j.1439-0310.2011.01931.x Abstract In oviparous species lacking parental care, successful reproduction depends on females selecting nest sites that facilitate embryonic develop- ment. Such sites may be limited in the environment, which can lead to multiple females using the same nest site simultaneously. However, there are several alternative explanations for communal nesting, includ- ing natal homing, predator satiation, and adaptive benefits to offspring. We used laboratory experiments to evaluate three hypotheses about nest-site selection in velvet geckos (Oedura lesueurii), which often nest communally. We investigated whether the trend to nest communally is influenced by the following: (1) evidence of previous nesting (hatched eggshells); (2) body size; and ⁄ or (3) thermal regimes. When given the choice, females laid their eggs in shelters containing hatched eggshells rather than in empty shelters, and this was not influenced by body size. Females selected nest sites that were cooler than their own mean selected body temperatures, suggesting that thermal requirements of their developing embryos could outweigh their own thermoregulatory preferences. Field observations of natal homing and high predation rates on gravid females suggest that imprinting on nest sites and ⁄ or predator swamping also play roles in communal nesting. Collectively, our results suggest that female velvet geckos use multiple cues to select appropriate nest sites, and hence that multiple mechanisms result in communal nesting behavior in this species. Ethology 796 Ethology 117 (2011) 796–801 ª 2011 Blackwell Verlag GmbH