Abstract
The leopard tortoise (Stigmochelys pardalis) is among the most ubiquitously distributed chelonian species in Africa. As with other chelonians, however, the species’ slow growth rate, coupled with low survivorship of juveniles, make it susceptible to declines under regimes of environmental perturbation. Here we studied the impact of electrified fences, a key source of mortality for many South African terrestrial vertebrate taxa, on leopard tortoise mortality in the Free State Province (Jacobsdal district) and Northern Cape Province (Strydenburg district), and its implications for survivorship of this population. Our results show a strong selection bias towards larger (breeding age) individuals that, given the life history of the species, should have strong (negative) consequences for populations. Using data for tortoise populations from other regions as a baseline for survivorship rates in populations unaffected by fencing, we derived a size-structure matrix model to evaluate the impact on population growth rates. Population projections, taking into account variation in survivorship and reproductive rates across and within size classes, indicated substantially higher risk of negative population growth (and eventual extinction) in populations affected by electrified fences. These results confirm that fencing is a conservation problem for the leopard tortoise population in this, and probably other regions, and highlights an urgent need for more intensive regulation of electrified fencing practices among landowners.
| Original language | English |
|---|---|
| Pages (from-to) | 32-52 |
| Number of pages | 21 |
| Journal | African Journal of Herpetology |
| Volume | 70 |
| Issue number | 1 |
| DOIs | |
| State | Published - 2021 |
| Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2021 Herpetological Association of Africa.
Funding
We dedicate this paper to the late Professor Margaretha (Retha) Hofmeyr, who provided invaluable input on leopard tortoise ecology, she will be sorely missed. We acknowledge the Palaeontological Scientific Trust (PAST) for their financial support towards SH’s PhD research, of which this paper formed a part, the National Museum, Bloemfontein, where the leopard tortoise collection is curated, Melissa Groenewald and Heidemarie Fölscher, who biannually assisted BW with the collection of specimens in the Jacobsdal area, Isaac Thapo and Abel Dichakane, who helped to collect the tortoise remains at Strydenburg and Jacobsdal and also prepared the specimens used in this study. We also thank the editor and anonymous reviewers for their useful comments that helped to improve this paper.
| Funders | Funder number |
|---|---|
| PAST |
Keywords
- chelonian conservation
- landscape barriers
- spatial ecology