Reptile diversity at Tswalu
In the last five years, reptile-focused research has become a mainstay at Tswalu Kalahari. The work is a collaboration between teams from the University of the Western Cape and the University of the Witwatersrand and falls under the Tswalu Foundation’s broader Kalahari Endangered Ecosystem Project. The research aims to understand which species of reptiles occur at Tswalu, how those species interact with their environment, and, ultimately, how changes to the environment impact their populations.
IMPACT OF BLACK THORN TREE DENSITY ON REPTILES
As atmospheric CO² increases, certain plant species are better able to grow in arid environments such as the Kalahari. At Tswalu, black thorn (Senegalia mellifera) trees have begun to form dense thickets in parts of the reserve. These dense stands probably impact reptile populations in important ways and may make parts of the reserve uninhabitable for some species. PhD student Riaaz Mohamed is trying to find out exactly how different reptile species respond to changes in tree cover.
It’s still early days, but Riaaz’s preliminary results show a complex relationship between reptiles and their habitat. Tree cover does not appear to impact reptile diversity. However, as tree cover increases, some species become more abundant, while other species become less abundant.
Riaaz’s PhD work will help scientists better understand the ecology of reptiles and allow us to adapt our management strategies to ensure the long-term survival of Tswalu’s amazing reptile diversity.
IMPACT OF CHANGING THERMAL ENVIRONMENTS ON CAPE COBRAS
Few Kalahari animals are as striking as a large, yellow Cape cobra. PhD student Thilo Beck is studying how the extreme thermal environment of the Kalahari shapes the biology of these amazing predators. Thilo wants to find out if changing thermal conditions will reduce the amount of time available to these snakes to find mates or seek food.
Thilo uses radio-transmitters and miniature temperature loggers implanted into the snakes to study their biology. With a radio receiver, he is able to track down and locate his study animals and make observations on their behaviour at the time. At the end of the study, the transmitters and loggers are surgically removed, and Thilo can go back and match his behaviour observations to measures of the snake’s body temperature and the temperature of the environment at the time.
Thilo’s research shows that extreme temperatures can drastically reduce the amount of time that cobras can spend above ground looking for food or mates. In summer, bouts of hot weather can significantly restrict their activity. As extreme weather events become more frequent, the biology of these iconic snakes will undoubtedly be impacted.
VALUE OF SOCIABLE WEAVER COLONIES TO REPTILE COMMUNITIES
Sociable weavers build huge thatch nest structures that dot the Kalahari landscape. Scientists have long known that Kalahari tree skinks preferentially choose trees with Sociable weaver colonies over similar trees without nests. Now, MSc student Emma Buckley is trying to find out if other species of reptiles also prefer trees with colonies in them.
Emma has confirmed the previous research by finding that Kalahari tree skinks are far more common on trees with Sociable weaver colonies than on trees without colonies. She has also taken the story further by showing that reptile diversity is much higher under trees with colonies and that Cape thick-toed geckos heavily utilize colony trees.
Emma has also found that Cape cobras prefer to forage around trees with colonies. This is because of the valuable food they gain from eating Sociable weaver chicks and eggs.
DISCOVERIES OF NEW REPTILE SPECIES
Researchers continue to discover species of reptiles not previously recorded at Tswalu. Last March, the team discovered that two closely related species of skinks both occur on the reserve although only one had previously been confirmed. More recently, the team added Common rough-scaled lizard to the growing Tswalu list. Time will tell which other little gems call Tswalu home without us knowing that they are here.
Images supplied by Bryan Maritz.
Making photos for National Geographic
The photographer, Thomas Peschak, takes us behind the lens to reveal the creativity, patience, time and luck that went into these once-in-a-lifetime shots.
The hyenas that call Tswalu home
Neither dog nor cat, there are three species of the hyena family found in Southern Africa, namely the aardwolf, brown hyena and spotted hyena. All three occur in the Kalahari and have made Tswalu their home.