The good mother: Does nest-site selection constitute parental investment in turtles?

Abstract

We tested the hypothesis that female midland painted turtles ( Chrysemys picta marginata Agassiz, 1857) provide significant parental care to their offspring through their choice of nest site. Painted turtle nest sites can be described in relation to specific microhabitat characteristics that, because of their effects on soil microclimate, may influence survival to hatch. We created models of the relationships between nest-site microhabitat and nest-site selection and between nest-site microhabitat and survival to hatch, and judged the fit of the models using Akaike’s information criterion corrected for small sample sizes. Female painted turtles selected nest sites with little canopy cover, little understory vegetation, and a southwestern slope aspect. Increased survival to hatch was associated with decreased organic content, which may serve as a surrogate for little or no vegetation or canopy cover. Nests in sites selected by turtles had slightly higher survival to hatch rates than nests in randomly chosen sites, suggesting that turtles may choose nest sites which increase offspring survival. Selection of nest sites may constitute significant parental investment and should be considered in studies of turtle life history.