Deep Communal Nesting by Yellow-Spotted Monitors in a Desert Ecosystem: Indirect Evidence for a Response to Extreme Dry Conditions

Abstract

Abstract In oviparous reptiles with no parental care, the choice of nest site is a mother's final investment in her offspring. Although linkages between nest site choice, egg temperatures, and embryonic success have been well studied, much less is known about analogous linkages with soil moisture encompassing developing embryos. Most ground-nesting reptiles nest at depths <25 cm, with the deepest nests <1.0 m deep. Recently, however, the nests of two species of monitor lizards (Varanus panoptes and V. gouldii) have been discovered at depths of 2.3–3.0 m, suggesting that nesting at extreme depths in these species is an adaptive response to the lack of sufficient soil moisture at shallower depths. Herein, we examine this idea with V. panoptes, specifically predicting that deeper nests in a desert ecosystem compared with those in a savannah ecosystem are attributable to differences in the magnitude of rainfall. We excavated a communal nesting warren to a depth of 4 m and identified 11 fresh nests and 99 hatc...