Nesting snakes (Tropidonophis mairii, Colubridae) selectively oviposit in sites that provide evidence of previous successful hatching

In oviparous species without parental care, nesting females must select an oviposition site that provides incubation conditions favourable to the developing eggs. Abiotic cues (e.g., temperature, moisture) are well known to influence oviposition-site selection, but the potential role of biotic cues (e.g., the presence of eggshells from previous successfully hatched clutches or the scent of egg predators) has rarely been examined in this respect. To test whether nesting females use such cues, we collected gravid keelback snakes (Tropidonophis mairii (Gray, 1841), Colubridae) in tropical Australia and gave them a choice of potential nesting sites in captivity. Females selectively oviposited in sites containing empty eggshells rather than in control sites but did not avoid the scent of a sympatric egg predator (the slatey-grey snake, Stegonotus cucullatus (Duméril, Bibron and Duméril, 1854)); indeed, eggshells of this taxon were as effective as keelback eggs in attracting oviposition. Our study adds to growing evidence that nesting females assess and respond to a diverse array of biotic as well as abiotic cues that predict the probability of successful incubation for their eggs.