ATTEMPTING TO RESURRECT THE DEAD: HERPETOLOGICAL SURVEYS WITHIN THE WOODBUSH REGION OF LIMPOPO PROVINCE.
Dr Oliver Cowan, Conservation Science Unit, [email protected]
Introduction
The Conservation Science Unit has been working on an ongoing project that aims to fill knowledge gaps on the distribution of Endangered species across South Africa. Right from the onset of our discussions held with herpetological (reptiles and amphibians – we’ll just use herp from now on) experts, the Woodbush region of Limpopo Province was highlighted as a region of interest. With high herp diversity and key questions regarding the potential presence of species of conservation concern there, the area was identified as a prime location for an intensive survey. However, with most of our team based in Cape Town, over 1,700 kilometres away, and travel restricted by the COVID-19 pandemic, the logistics of organising such a trip proved to be challenging!
The most alluring aspect of surveying the Woodbush area was the possibility of finding a reptile considered the ‘Holy Grail’ within the South African herp community. Eastwood’s Long-tailed Seps (Tetradactylus eastwoodae) is known from only two specimens collected in the early 1900s – both catalogued as being from “Woodbush”. In the 1980s, there were several searches for the species, and, in 2008, a ten-day survey was conducted in the Woodbush/Haenertsburg area, but all were unsuccessful. Despite anecdotal claims of sightings of the species in the fragmented grassland patches, which, for now, have escaped the afforestation and agricultural expansion characteristic of the region, the species is officially listed as Extinct.
Although rediscovering T. eastwoodae would be the primary aim of the field trip, spending time exploring such a remote and poorly surveyed location would also allow us to get a good handle on the current herp community and help answer several other questions with regards to their distribution. To answer these questions, we assembled a crack team of on-the-ground researchers from institutes such as the South African National Biodiversity Institute (SANBI), Port Elizabeth Museum, Rhodes University, and the Limpopo Department of Economic Development and Tourism (LEDET), not to mention our own in-house experts, with valuable support in the planning process from researchers at WITS, University of Pretoria, and the EnviroInsight Consultancy.
Survey Methods
Following a survey, both via satellite imagery analysis and in-person, we selected some suitable sites for traps, and highlighted more remote areas to target for active searching. During this selection process, we based our decisions on the results of previous surveys conducted in the area, the current state of the vegetation in the area, and the different land uses, both historical and contemporary. We employed a trap design that incorporated drift fencing, pitfall traps, and funnel traps. As illustrated, each trap consists of three ‘arms’ of drift fencing (plastic sheeting, each ~10 m in length, staked into the ground), with pitfall traps (buckets dug into the ground with the rims are at ground level) placed at each end, and one in the centre where the arms meet. We placed funnel traps on both sides of each arm (six in total per trap) at ground level. In theory, any small animal that moves through the landscape and reaches the drift fence is diverted towards either a funnel trap or a pitfall trap, where they are contained until we can identify them, take DNA samples, and subsequently release them. As all fieldwork carried out by the EWT requires ethics approval from an independent panel, we ensured that all traps were insulated and sheltered to prevent captured animals from suffering the effects of exposure to the elements, and traps were checked at least once per day.
Key findings
Unfortunately, despite our best efforts, we were unable to rediscover Tetradactylus eastwoodae. It is a cliché in science but a truism nonetheless: an absence of evidence is not evidence of absence. Thus, although the species remains listed as extinct, we remain cautiously hopeful that it still survives out there somewhere. Certainly, that is the opinion of the expert herps we worked with during the two-week survey, and we hope that the insights gained from our on-the-ground experience will assist in refining future surveys.
With the bad news out of the way, the focus can now turn to the positive outcomes from the trip. A total of 50 unique species (ten amphibians and 40 reptiles) was identified during the survey from a combined total of 208 observations! Not only is this a substantial contribution to our understanding of the herp metacommunity of the region, but certain key findings may be important in refining our knowledge of the distribution of species of conservation concern. These species include Methuen’s Dwarf Gecko, Northern Forest Rain Frog, and the Woodbush Legless Skink. Furthermore, we obtained DNA samples of species with some degree of taxonomic uncertainty surrounding them – such as the Natal Ghost Frog, Mozambique Rain Frog, Berg Adder, Wolkberg Dwarf Chameleon, and African Flap-necked Chameleon. These samples are particularly valuable as they originate from a remote, poorly surveyed region. The outcomes of the genetic analysis may help to clarify the taxonomic status of these sup-populations, an under-appreciated aspect of effective species conservation. In some cases, the subpopulation may even be newly classified as a unique species! Conclusion and Acknowledgements
After two COVID19-induced false starts, we finally managed to spend two weeks on-site during March 2021. Although the trip’s primary goal, the rediscovery of Tetradactylus eastwoodae, ultimately proved unsuccessful, the survey was a success. A total of 50 unique species was observed during the two weeks, and over 200 individual records were added to our database. The key findings include delineating the distribution of the Vulnerable Lygodactylus methueni and Near Threatened Acontias rieppeli and collecting DNA samples from seven species with phylogenetic question marks hanging over their status.
We would firstly like to thank the Rand Merchant Bank Foundation for providing funding for the entire project. Secondly, LEDET and SAFCOL kindly provided us with research permits, without which we would not have been able to conduct our survey. Thirdly, Lamei Lodge provided a discount on accommodation, allowing us to be based at a suitable location. And finally, Justin Henry for assistance with setting up the traps.