Burrow site selection in the Sungazer (Smaug giganteus): a threatened South African endemic lizard

ABSTRACT

Elucidating factors that drive microhabitat selection in a species is important for informing the conservation management of the species. For species that use microhabitats as long-term refuge sites, selection pressures are likely to be strong because the microhabitat must fulfil their eco-physiological and life history requirements. Smaug giganteus (Sungazer) is a threatened (Vulnerable) cordylid lizard species in the highveld grasslands of South Africa – a key agricultural area in the country. Individuals dig burrows as refuges, which increases their sensitivity to habitat transformation. In addition, previous attempts to translocate populations have failed due to a lack of knowledge about their specific microhabitat requirements. We assessed microhabitat characteristics that may influence burrow site selection by measuring vegetation characteristics surrounding Sungazer burrows and comparing these to vegetation at randomly selected sites. We also recorded orientation, aspect, soil composition, and the presence of other animal dung. Sungazers selected sites with sparse vegetation cover, and where grass height was short, but had no preference for soil composition. There was no relationship between the presence of ungulate dung and the placement of Sungazer burrows. Most Sungazer burrows were orientated in a northerly direction on north-facing slopes, suggesting that burrow placement has thermoregulatory advantages. We recommend that to identify suitable sites for Sungazer translocations, landscapes are thoroughly surveyed with cognisance to the findings in this study, and that a soft-release translocation protocol follows to maximise translocation success.

KEYWORDS:

• burrow selection
• habitat transformation
• grassland
• microhabitat
• reptile
• Smaug giganteus
• vegetation cover

Acknowledgements

We thank the Rufford Foundation (grant number: 29137-1) and The Alexander Herp Lab for providing the financial support to undertake this research. We also thank Shivan Parusnath for supplying us with locality records of Smaug giganteus, and Bradley Gibbons for providing connections to landowners. Importantly, we thank all landowners for granting us permission to conduct this research on their properties. The Department of Economic, Small Business Development, Tourism and Environmental Affairs (permit numbers: JM5067/2019 and 202112000008380) provided permission to conduct this research within the Free State province, South Africa. We received ethical clearance by the University of the Witwatersrand’s Animal Ethics Screening Committee (ethics numbers: 2019/04/29B).

Disclosure statement

No potential conflict of interest was reported by the author(s).