Deep communal nesting by yellow-spotted monitors in a desert ecosystem

Indirect evidence for a response to extreme dry conditions

J. Sean Doody, Colin R. McHenry, Louise Durkin, Mike Brown, Angela Simms, Lizzy Coleman, Charlotte Phizacklea, Hayes Jones, Oliver Phizacklea, Simon Clulow

Research output: Contribution to journalArticle

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 hatched nests. Mean nest depth in the present study was greater than that in savannah. However, nests were shallower than those of V. gouldii in the same general location, possibly because of local heterogeneity in soil moisture. Hatchlings excavated their own emergence burrows rather than following the burrows of their mothers, despite relatively great distances through resistant soils. Collectively, deep nesting creates energetic challenges for mothers and hatchlings, suggesting an adaptive function for the behavior.
Original languageEnglish
Pages (from-to)306-310
Number of pages5
JournalHerpetologica
Volume74
Issue number4
DOIs
Publication statusPublished - Dec 2018

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Keywords

  • eggs
  • incubation period
  • nest site choice
  • wet–dry tropics
  • reptile
  • Varanus panoptes

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