Protecting the
geometric tortoise:
A conservation case study

by CapeNature

The geometric tortoise is one of the most well-known critically endangered species in the Western Cape, despite the fact that the majority of the population has never seen one. This is mainly due to the efforts of CapeNature to profile the species over the past two decades, illuminating the public on the struggle to conserve this unique species.

Geometric Tortoise

Geometric Tortoise 
Psammobates geometricus

Currently, the species is on a knife-edge, but conservation efforts focusing on a number of different factors are hoping to push the geometric tortoise back to stability.


 HABITAT

“The geometric tortoise is interlinked with the habitat it lives in – shale renosterveld and alluvium fynbos. As the habitat has declined over the years, so has the tortoise population”, says CapeNature’s Dr Ernst Baard, who has dedicated most of his scientific career to studying the geometric tortoise. Given the small area in which shale renosterveld and alluvium fynbos occurs, it’s hardly surprising that there is increasing pressure on the species.

That is why CapeNature has embarked on a series of projects attempting to not only secure more land for the nature reserves where the geometric tortoise occurs, but also encourages private landowners to enter into stewardship agreements. When it comes to protecting the geometric tortoise, both of these avenues provide successes and failures.

The crux of the matter is that where 100 years ago there would have been large swathes of shale renosterveld and alluvium fynbos in the Swartland, upper Breede River Valley and Ceres Valley, and thus large uninterrupted areas for the tortoises to live, more than 90% of those have now disappeared to make way for human settlements and farm lands while, in the best cases, only small pockets remain, isolated from the surrounding areas.

There has been a large amount of buy-in from landowners, though, mainly farmers who are increasingly aware of the crucial role they play in the ecosystem. “We couldn’t have done much without the landowners we’ve engaged with, who have been more than willing to set aside land for the conservation of the species”, says Dr Baard.

Regardless, the strain on the habitat puts strain on the tortoise population. Previously, tortoise populations were able to travel across wide areas of land – now they are confined to small areas, leaving them vulnerable to wildfires, predators (often times introduced, such as feral pigs) and other factors, as well as isolating population groups, leading to a reduction of genetic diversity.

“One of CapeNature’s biggest challenges is to come up with innovative ways to look after these remnants of veld,” continues Dr Baard.

Success in that regard has come recently in the form of a large patch of land which was purchased specifically for the conservation of the geometric tortoise. This land was purchased by the Turtle Conservancy, an international non-governmental organisation dedicated to saving the world’s  tortoises, turtles and terrapins, by boosting the extent of natural habitat under protection in an effort to secure a future for another portion of the population.

Watch this short video on the land, put together by the Turtle Conservancy, to learn more:

But the challenges don’t stop there.


CLIMATE CHANGE

Compounding the pressure has been the increasingly unpredictable weather, caused by climate change.

“I’ve learned throughout my career that the successes come slow and the failures can be sudden. With the geometric tortoise, it takes 10 to 12 years for an individual to reach sexual maturity, so population growth takes place over decades. But you might see an entire section of the population getting wiped out overnight due to a wildfire.”

And extreme weather only increases the incidences of wildfires, as well as other natural disasters, such as drought. More fires and drought mean more assaults on the tortoise’s habitat, more regularly.

When that habitat is already significantly reduced, the risk to the population becomes even higher. With little place to hide, and fences surrounding their habitat, entire populations become vulnerable to these extreme weather events.


 PREDATION

For the geometric tortoise, predators have traditionally been limited due to the large landscape, and presence of other prey in larger numbers.

Now, however, predators such as baboons, jackals, Pied Crows and invasive feral pigs occur in geometric tortoise areas, often in higher than ‘natural’ numbers due to the same human development and agriculture that has put pressure on the geometric tortoise.


 HOPE FOR THE FUTURE

The situation outlined above may seem bleak, but there is always hope in conservation. CapeNature and conservation partners have focused on a number of core areas, including engaging with private landowners to secure stewardship agreements, or to buy up ‘unused’ land and add that land to the province’s list of Protected Areas.

There is also a programme aimed at eradicating the feral pig populations in geometric tortoise habitat, as well as effective deterrent measures for Pied Crows and baboons to limit the rates of predation.

Research programs are also under way to determine exact population numbers and distribution, as well as the genetic diversity across populations which are separated by large mountain passes.

The conclusion to be drawn, then, is that while the geometric tortoise may seem to be up against a whirlwind of combined factors, the interventions by scientists, researchers and conservationists like Dr Baard and research and conservation partners such as Prof. Margaretha Hofmeyr, previously of the University of the Western Cape, and the Turtle Conservancy, mean that hope is never lost.

geometric-tortoise


The case of the geometric tortoise is not unique. All of these factors are ones faced by a number of fauna and flora across the Western Cape, and we will be profiling these more of these species throughout the year.

To find out more about CapeNature’s conservation work, click here.

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