Winter BioMAPping and Botanizing in Venda

On Friday, 12 June 2020, my friend Ruan Stander and I embarked on a reptile-and-plant-biomapping expedition in Venda. Venda is a wonderful and wild region in north-eastern South Africa. It is a very biodiverse area and poorly biomapped.  Ruan is the expert on reptiles and amphibians; my own specialty is plants. It was the middle of winter here in South Africa, but where we went, it was warm, and at a much lower altitude than our hometown of Polokwane. The climate around Venda is ideal for cold-blooded critters. We set up our tents a short distance from the Cross Dam on the Nwanedzi River. The region is sparsely populated; we only met some folks at the dam on the first day, and on the second night some people came by our tents with flashlights and dogs; they might have been hunting, and didn’t bother us. We also went to the small settlement of Masisi, the Bende-Mutale region, and the Honnet Nature Reserve, but we slept each night at our Cross Dam camp.

Ruan’s goal is to find and photograph as many of Limpopo’s reptile species as possible.  He had several goals for this outing; and we found at least some of our targets! The habitat at Cross Dam is rocky hills covered in arid woodland. There are patches of lush riverine forest with large trees bordering the Nwanedzi River. A bit to the north, there are flat, sandy areas. At Masisi there are well-vegetated rocky hills; Bende Mutale is mainly flat, dry Mopane veld. Honnet Nature Reserve has a dry climate, with a large, rocky hill and an old, huge, now-vegetated dune of red Kalahari sand.  These all gave us numerous habitats for finding different reptile species.

I was of course also interested in the plant life! The hills around Venda are a northern extension of the Soutpansberg Mountain range, one of the most plant-diverse parts of South Africa.  A tree that is very characteristic of this region is the Lebombo Ironwood, Androstachys johnsonii, an ancient species that occurs in South Africa and Madagascar.  In higher rainfall areas of the mountains, they form dense forests, but in the dry areas the trees were shrubby and stunted, only occasionally forming small thickets. Other characteristic plants of this region are the giant Baobab trees, one of which was pretty much the tallest one I’ve ever seen – close to 30 m! 

The region is characterized by several other thick-set trees and large succulents, like Star-chestnuts, Sterculia rogersii, Sesame Bushes, Sesamothamnus lugardii, the grotesque Elephant’s Foot, Adenia spinosa, and the beautiful flowering Impala Lily, Adenium multiflorum. The impala lilies we came across were some of the largest I have ever seen, about 2,5 m tall, with trunks more than 0,5 m in thickness. The flowers were lovely amidst the dry, harsh landscape. 

Another amazing thick-stemmed specimen was of a Sesame Bush (photo above), that appeared to be two separate plants, but was actually a single plant – just as with the Wonderboom Fig tree in Pretoria, but on a more modest scale. One branch drooped to the ground, set root, and produced a second trunk with branches. It’s the first time I have seen this happening with anything other than a fig tree. I was happy to note numerous individuals of other trees I consider as fairly rare, such as the Propeller Tree, Gyrocarpus americanus subsp. africanus and the Mountain Mahogany, Entandrophragma caudatum.  

Other nice finds included two species of carrion flower in the genus Stapelia, a rare tree-like succulent restricted to the Soutpansberg mountains, Euphorbia zoutpansbergensis, and a Sand Impala Lily or Bitterkambro, Adenium oleifolium, in the sandy region to the north of our camp.  The Bitterkambro is related to the Impala Lily, and is more typical of the Kalahari Desert region. This record we found is the most easterly record as far as I am aware, so it was a wonderful find. 

The Honnet Nature Reserve had interesting dune plants; and one of the largest Shepherd’s Trees, Boscia albitrunca, I’ve ever seen, with Ruan for comparison (seen in the cover photo).  In Afrikaans it’s known as a Witgat or Matoppie. This is an arid-adapted species, that has among the longest roots in the entire plant kingdom. A medium-sized Shepherd’s Tree can have a tap root going down into the sandy soil as deep as 60 m!

We were looking for reptiles day and night. Flat lizards, Platysaurus rhodesianus, and rainbow skinks, Trachylepis margaritifer, clung to the steep rock faces around the dam region, as well as tropical spiny agamas, Agama armata.  At night, we found flat geckoes, Afroedura pienaari, velvet geckoes, Homopholis wahlbergii, Turner’s geckoes, Chondrodactylus turneri, tropical house geckoes, Hemidactylus mabouia (using a huge baobab as a house), and one of our targets, the Tiger Thick-toed Gecko, Pachydactylus tigrinus. Young ones curl their tails up over their backs in defense, to resemble scorpions (of which we also found many!).  We also found a few geckoes during the day, including a Speckled Thick-toed Gecko, Pachydactylus punctatus, and some Bradfield’s Dwarf Geckoes, Lygodactylus bradfieldi.

In the day, in the woodland, we encountered bushveld lizards, Heliobolus lugubris, common rough-scaled lizards, Meroles squamulosus, Holub’s sandveld lizards, Nucras holubi, LOTS of Damara variable skinks, Trachylepis damarana, and the small but cute spotted-necked snake-eyed skink, Panaspis maculicollis.  Under rocks and logs, we found the burrowing species.  These lizards have reduced or even missing limbs.  They’re a wonderful example of natural selection taking place almost in front of your eyes as you compare the different stages of leg reduction. Sundevall’s writhing skink, Mochlus sundevallii, a sleek and glossy species, still has small but fully-formed limbs, but the Limpopo dwarf burrowing skink, Scelotes limpopoensis, has tiny legs and mere stubs for ‘arms’.  The Richard’s legless skink, Acontias richardi, as you might conclude has no legs at all; though resembling a small snake, it is still a proper lizard – like the other two, it belongs to the skink family.  It’s a rare species, restricted to the region. 

We did find a true snake, a tiny black-headed centipede eater, Aparallactus capensis; showing its “snakeness”, it fitfully flicked out its little tongue as we held it. One of the most special finds of the outing was made by Given, a local who joined us on the Bende-Mutale and Masisi parts of our excursion. It was a slender spade-snouted worm lizard, Monopeltis sphenorhynchus! These reptiles look amazingly similar to earthworms. They belong to a group called the Amphisbaenians, a sister group of the true lizards. 

Apart from the reptiles, there were many other memorable moments of the trip. We encountered mammals: at night, the thick-tailed bush-babies called all around us. We found gerbils amongst the rocks and also a mouse, which I couldn’t identify, but got so close to it that I touched it! We also encountered a genet close to our car, and each morning, as we sat in the car and ate breakfast, a little rock elephant shrew came out and hopped about the rocks and stones next to the river. Elephant shrews or Sengis, are remarkable critters, actually more closely related to elephants than to other shrews. On the rocky hills, we saw what might have been a bush hyrax. And we had sightings of Chacma baboons.

We encountered birds: along the stretch of river where we had parked, there were no less than three species of kingfisher! The giant kingfishers called and flew noisily back and forth; the pied kingfisher was rather more subdued, and least obtrusive of all, but quite lovely, were a couple of half-collared kingfishers that had their territory amidst some lovely riverine forest trees. One morning a Burchell’s coucal, usually a shy bird, sunned itself out in the open in front of our car, displaying its beautiful bright reddish-brown wings. We even glimpsed a splendid Verreaux’s Eagle soaring high above the cliffs.

We encountered amphibians: at night, near the river we found river frogs, some of them even mating in the middle of winter!  There were also tropical clawed frogs in the still pools, and we found a little dwarf Puddle frog, Phrynobatrachus mababiensis, as well.

We encountered invertebrates galore! Looking for reptiles under rocks and logs, we often found spiders, scorpions, centipedes, millipedes, woodlice, cockroaches, ants and termites. In the photo below Ruan is holding a large scorpion.  The scorpion was quite placid and at any rate its thin tail shows that it’s not very dangerous.  An unusual sighting was that of a mole cricket (Gryllotalpa species) next to the river at night. This species is well-known for occurring in well-watered suburban gardens, but its natural habitat is that of moist grassy spots next to rivers or pools. 

We found 25 different reptile species in all.  I found some rare and unexpected plants.  It was quite a successful bio-surveying outing.  Reptiles, as well as plants, are quite vulnerable to environmental changes, and thus can serve as indicators of environmental health.  But more importantly, they are beautiful, exquisite and fascinating beings in their own right, and they all deserve as much protection as we can give them. A big thank you to Ruan, Given, and our Honnet Nature Reserve Guide, Joseph Saunders, for a lovely adventure.

PHOTO CREDITS:

Ruan Stander: Bradfield’s Dwarf Gecko, Campsite, Common River Frog, Cross Dam, Dwarf Puddle Frog, Euphorbia zoutpansbergensis with me, Halfcollared Kingfisher, Huge Baobab with me, Impala Lily flowers, Limpopo Dwarf Burrowing Skink, Richard’s Legless Skink, Rock Elephant Shrew, Spade Snouted Worm Lizard, Spotted-necked Snake-eyed Skink, Tiger Thick-toed Gecko (both), Tropical Spiny Agama.

Willem van der Merwe: Baobab, Bitterkambro, Black-headed Centipede Eater, Stapelia getliffei flower, Stapelia kwebensis plant, Elephant’s foot with Ruan, Euphorbia zoutpansbergensis, Impala lily plant, Impala lily with Ruan, Scorpion, Sesame Bush with Ruan, Sundevall’s Writhing Skink, Shepherd’s Tree with Ruan.