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Best solution is to remove the exotic Sambar deer from Table Mountain National Park

Brian van Wilgen
By Brian van Wilgen
6 Mar 2025
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Sambar deer have established feral and invasive populations in Australia, New Zealand and Florida, where there is evidence that they impact negatively on biodiversity, water quality from catchments, and pose a risk of transmission of diseases.

I work in the field of biological invasions, which examines the causes and consequences of introducing plants and animals to parts of the world where they are alien. Some, but certainly not all, of these alien species become invasive, and this phenomenon is increasingly impacting negatively on ecosystems across the world.

Quite often, there is no question about the harm done by such “pests” or “weeds” and no argument that they should be controlled or eradicated. But sometimes it is not that clear, and disagreements arise.

It was therefore with interest that I read the recent Daily Maverick article by Professor Nicoli Nattrass on alien Sambar deer in the Table Mountain National Park (TMNP) (“Exotic Sambar deer on Table Mountain: Do the research first, shoot later,” 26 February 2025).

This article raises several points, including that there is no evidence that they cause any harm and are being culled simply because they are alien; that there are no plans for such culling, which is consequently ad hoc, or reports on its effectiveness, as required by law; and that the deer may well be doing more good than harm.

A closer look


On the face of it, these seem like logical concerns, but a few things need closer examination.

Sambar deer were introduced from Asia and are listed as an invasive alien species by the Department of Forestry, Fisheries and the Environment (DFFE). This listing means that SANParks (and any landowner who has Sambar deer on their land) is required by law to take steps to control the species. 

Thus, if SANParks did not control Sambar deer, they would be in breach of the law. One can certainly question why Sambar deer are listed, and whether such listing is justifiable, but in the meantime the TMNP must control them because they are listed, not simply because they are alien.

However, it would be a cop-out to use this as an excuse to fob off criticism.

Prof Natrass points, quite correctly, to a lack of documented scientific evidence on the impacts of Sambar deer in South Africa. However, a justification for listing can be based on documented impacts of the species outside of its native range, even if these impacts are recorded outside of South Africa. Such decisions are based on risk analyses that are compiled following a strict protocol.

Sambar deer have established feral and invasive populations in Australia, New Zealand and Florida, where there is evidence that they impact negatively on biodiversity, water quality from catchments, and pose a risk of transmission of diseases.

In addition, research has shown that the largest impacts from introduced ungulates are likely to arise when they perform novel functions in the new environment.

Historically, there were no large antelope on the Cape Peninsula, except for eland and hartebeest, which were grazers and were confined to the grassy slopes of Signal Hill and Devil’s Peak.

Prof Nattrass also suggested that some impacts of Sambar deer may be positive – they could potentially slow the spread of forests (which are expanding because of fire suppression), reduce fuel loads by feeding on flammable plants, or assist with the control of alien plants by browsing on them.

These benefits are speculative, and they seem unlikely. For example, localised browsing on pine trees is not going to stop their spread, and reducing fuel loads could further reduce fires and thus encourage the spread of forests.

Management plans


Prof Nattrass also points out that the law requires protected areas to develop a plan for invasive species control and to produce regular status reports on the efficacy of such management. She was apparently unable to obtain such reports, leading to “a growing suspicion that these plans and reports don’t exist”.

These reports do exist however, and both the park management plan and a status report can be downloaded.

It is true that the management plans for invasive alien species have a focus on a few of the most prominent species, but this needs to be put into perspective. A plan is not required for every single species, but for the protected area as a whole.

Populations of around 300 alien species (250 plants and 50 animals) have become established in the TMNP. It would simply be beyond the capacity of cash-strapped and under-resourced parks to develop and implement individual plans for control and to monitor their outcomes for 300 species, so the focus has to be on the priorities.

The plan does provide details on the management of priority species, and lists the management of others as ad hoc, meaning that the necessary control will take place as resources allow and as opportunities arise.

The Table Mountain National Park has made substantial progress towards achieving the goals of reducing invasions by alien species to levels that can be managed sustainably in future, despite facing many challenges and ongoing criticism.

Progress


It is pleasing to see this progress in a unique and biodiverse area, with many species found nowhere else on Earth, and which has been granted World Heritage Site status in recognition of its outstanding universal value.

The operations aimed at the control of priority invasive alien species have been carefully monitored, arguably providing the best example of such practices for any protected area in Africa.

Despite these successes, the future of Sambar deer on Table Mountain will remain contentious. People differ in their level of understanding, their perceptions and their values regarding this issue.

On the one hand, evidence from other parts of the world suggests that these deer could impact on Table Mountain’s unique endemic fynbos plant species that are not adapted to heavy browsing by large mammalian herbivores. It is our duty to protect these indigenous species from real or potential harm.

On the other hand, others point to the current lack of studies documenting harmful impact. Continued culling would result in continued controversy without a clear endpoint in sight.

But retaining populations of large alien mammals in a sensitive and globally important protected area, without control, would carry ecological risks. The best solution would seem to be to remove this small population from the park entirely.

A decision on which route to follow should be preceded by an assessment of the feasibility and desirability of such eradication. The South African National Biodiversity Institute has established a unit to specifically carry out such assessments, and this could be seen as a priority project.

Our conservation agencies face enormous challenges in the task of protecting our indigenous biodiversity and all of the services it provides, and can ill afford the distractions brought about by debates such as this. DM

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