Thermal consequences of subterranean nesting behavior in a prairie-dwelling turtle, the Ornate Box Turtle (Terrapene ornata)


Many oviparous reptiles deposit eggs in excavated nest chambers, and the location and depth at which eggs are laid can affect predation risk, incubation duration, mortality rates, and hatchling phenotype. Among turtles, nest depth also influences incubation conditions of some large-bodied species, but nest depth is generally expected to vary less among small-bodied species. We monitored nesting behavior of Ornate Box Turtles (Terrapene ornata (Agassiz, 1857)) for two seasons in Illinois. We used direct observations to confirm that, among 31 nesting events, six females oviposited while beneath the substrate surface. Furthermore, comparisons of body length to nest depth indicated that five additional females likely also constructed nests while buried. Nests laid while females were underground were deeper, on average, than other nests (16.7 versus 11.2 cm), and while mean nest temperatures were similar between groups, temperature fluctuations and maximum temperatures were lower among nests that were laid while females were underground. Subterranean oviposition appears to have moderated incubation temperatures by allowing females to deposit eggs at greater depths than would be possible from the surface. This little-documented behavior may be a mechanism for this species to influence the incubation environment, which in turn may influence hatchling phenotypes.



Document Type





Incubation, Nest-site selection, Ornate Box Turtle, Phenotypic plasticity, Terrapene ornata, Thermoregulation

Publication Date


Journal Title

Canadian Journal of Zoology