SNAKES ON THE PLAIN? THE SOUTHERN ADDER: SMALL, CAMOUFLAGED AND VERY VULNERABLE
Dr Oliver Cowan, Conservation Scientist, EWT Conservation Science Unit
The Southern Adder was once found in coastal Fynbos plains throughout the Western Cape; however, due to urban development and increased agriculture it is now only found in two disjunct populations: one on the Southern Cape coast; the other along the West Coast. This cryptic, dwarf adder is classified by the IUCN as Vulnerable and its future is in peril due to predicted habitat loss. While its distribution along the Southern Cape coast is fairly well understood, the same cannot be said about the West Coast sub-population. Once considered wild and desolate, the last few decades have seen a rapid rise in coastal development and confirmed observations of the Southern Adder have been few and far between. It was in this context that members of the Conservation Science Unit, alongside collaborators from SANBI, set out at the end of last year to extensively survey suitable habitat along the West Coast as part of the ongoing project to map the distribution of species of conservation concern.
The Southern Adder does not however, want to be found. Indeed, as an ambush predator its livelihood relies on staying hidden – allowing its prey to unwittingly approach within striking range. The species is small (on average the size of a ruler) and highly camouflaged. It is adept at both lying motionless, half covered in sand, and climbing shrubs to seek refuge in the branches. During our week of active searching, trekking for kilometres through sandy soils and prickly Strandveld, we encountered numerous fascinating creatures but did not catch sight of a single Southern Adder. In the sandier areas, we could even find snake tracks, but distinguishing between species is challenging and just as we thought our search had been a success we ended up eye-to-eye with a grumpy Puff Adder, the Southern Adder’s larger and more venomous relation.
The next day we had another near miss, but this time we had something tangible to show for it: a photograph. We had arranged to meet the conservation manager of Grotto Bay Private Nature Reserve to get the lay of the land before surveying the reserve. Upon arrival he showed us a picture one of the residents had sent him from her morning dog walk – a pic of a supposed baby Puff Adder. In fact, the snake in question was clearly a Southern Adder and we rushed off to where the photo had been snapped. Despite spending the entire afternoon scouring the adjacent veld, we could not rediscover it. Nevertheless, we were heartened. The picture was irrefutable proof that the species was still present in the region and provided a valuable new occurrence record! We subsequently reckoned that active searching may not be the most efficient method of locating these serpentine Houdinis and decided to implement Plan B.
Plan B involved using the relationship we had forged with private landowners to implement a longer-term strategy and utilise citizen science. A popular residential model in the area is private nature reserves – large areas containing permanent and holiday residences within fenced-off nature reserves. We had been based at one such reserve, Jakkalsfontein, during the course of our trip and had been allowed by the reserve manager to place coverboards strategically throughout the reserve. These 1×1 metre wooden boards provide cover for reptiles from predators and, by marking their location, we could return to them each day to inspect them. With our time in the field drawing to a close we requested whether we could leave the boards in place and visit them on occasion. Not only was this request granted but the reserve manager kindly volunteered for his own rangers to inspect them when able to do so. In addition, we posted a brief note in the local newsletter explaining the purpose of our work and what residents should do if they encounter a Southern Adder.
The Southern Adder (Bitis armata) found at Jakkalsfontein (photo credit: Nick Telford, SANBI)
Early in the new year we received word that a resident at Jakkalsfontein had found a “slangetjie” (small snake) in the shrubs on his front yard and alerted a ranger who had subsequently caught it. Although I was busy at a workshop, my colleague from SANBI raced up the N7 to confirm the Southern Adder’s identification and take a DNA sample before releasing it unharmed into the reserve. The DNA sample will be used to compare this Western sub-population to its Southern counterpart, with important conservation implications. Furthermore, we have been encouraged by the interest shown by both the land managers and residents of the region for this small, but beautiful creature. So much so that we have tentatively begun exploring the potential to set up and maintain natural corridors between farms and nature reserves to increase habitat connectivity. Increasing connectivity allows for greater dispersal, hopefully preventing genetic bottlenecking which can often occur within isolated populations. If this proves viable, it will be directly attributable to motivated and conservation-minded citizens. But, from the experience of our brief stay in the region, this will be the smallest hurdle to overcome!
We are grateful to Rand Merchant Bank for funding the project; Les from Grotto Bay Private Nature; !Kwha Ttu San Cultural and Heritage Centre; Steyn Marais; Prof. Greta Geert; and Therese Hulme at Jakkalsfontein Private Nature Reserve.
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