Animals may aggregate either because the presence of conspecifics provides information about habitat suitability, or because the presence of conspecifics directly enhances individual viability. For a female lizard, the advantage of laying her eggs in a communal nest may entail either information transfer (hatched eggshells show that the site has been successful in previous seasons) or direct physiological benefits (recently-laid eggs can enhance water availability to other eggs). We tested the relative importance of these two mechanisms in the three-lined alpine skink (Bassiana duperreyi Gray, 1838) by offering gravid females a choice between sites with hatched eggshells versus freshly-laid eggs. Females selectively oviposited beside fresh eggs. In this species, early-nesting females use information transfer (i.e. the presence of old eggshells) as a nest-site criterion, whereas later nesters switch to a reliance on direct benefits of conspecific presence (i.e. the presence of freshly-laid eggs).
- oviposition site choice
- proximate cues