Opinionistas

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Time for a moratorium on culling Sambar deer in Table Mountain National Park

24 Mar 2025

If we find that Sambar deer are not a threat to endangered fynbos and that they preferentially consume aliens (including invasive kikuyu grass) without spreading them, then they should be left alone.

Should SANParks know what they are doing before they shoot animals on Table Mountain?

Brian Van Wilgen, an eminent invasion biologist, recently took issue with my call for more research before shooting Sambar deer on Table Mountain. He accepts the need for “prior assessment of the feasibility and desirability” of killing them, but nevertheless opines that the “best solution would seem to be to remove this small population from the park entirely”.

Van Wilgen’s argument against Sambar proceeds in the inferential manner typical of invasion biology: point to the general problem posed by invasive species (citing a review that does not refer to Sambar); warn about the dangers posed by alien ungulates in novel contexts (also citing a paper which does not reference Sambar); remind us of the need to protect Table Mountain’s unique flora; note that historically there were no large herbivores on Table Mountain; and conclude that Sambar should thus be eradicated.

Such an argument suggests, without actually showing this, that Sambar are invasive on Table Mountain, pose a threat to endangered fynbos, undermine our efforts to restore some timeless pristine ecosystem, and therefore must be killed.

Sambar deer grazing on kikuyu garden grass on the slopes of the Table Mountain National Park. (Photo: Jonno Sherwin)

Curiously, Van Wilgen ignores two past substantial assessments for which he himself was the lead editor. One reported that Sambar were not thought to have serious impact and were not listed in the regulations as invasive. The second reported that their impact on Table Mountain was likely to be “negligible”.

Van Wilgen states that Sambar pose ecological dangers in other countries such as Australia where they persist in larger numbers. But the evidence for this is thin and context specific, as a 2016 review concluded. Sambar are not regarded as an ecological threat in New Zealand, but in some Australian contexts have been shown to consume more native than alien plants while spreading more alien seeds.

A recent study of Sambar in Australian eucalyptus forests found that they did not affect species richness but nevertheless posed a potential ecological threat in their preference for tree ferns.

We clearly need to know more about the Sambar population and diet in our context. If we find that the Sambar are selectively damaging important plants and spreading, rather than controlling, alien vegetation on Table Mountain, then there is an argument for keeping them out of at-risk areas and even culling them.

If we find that they are not a threat to endangered fynbos and that they preferentially consume aliens (including invasive kikuyu grass) without spreading them, then they should be left alone.

Local research lacking

Van Wilgen argues that Table Mountain National Park is complying with legal reporting requirements when it notes that Sambar are being culled on an ad hoc basis (I beg to differ) but in any event is required by law to cull Sambar because they are listed in the alien and invasive species legislation.

This is all very circular, however, because such listing is based on input from invasion biologists like Van Wilgen – and in the case of Sambar, without the benefit of any local research. Neither SANParks nor these invasion biologists apparently feel the need to know how Sambar impact on the local ecosystem before reaching for their guns.

It is true, as Van Wilgen points out, that Table Mountain did not historically support large herbivores. Before human settlement, unchecked fires from the north and the southeast drove forests into ravines and fire shadows, eliminating the ecological niche Sambar now occupy.

Shooting the Sambar will not restore that earlier fire-shaped ecosystem: the existence of the city puts paid to that. We need to accept the reality that Table Mountain is a unique natural resource surrounded by people concerned about fire and that this has shaped the ecology over more than a century, allowing the Afromontane forest to expand. Maintaining the biodiversity and ecological integrity of Table Mountain has to proceed explicitly within that constraint.

We thus need to take seriously the possibility that Sambar may occupy a useful ecological niche and that by browsing the forest understorey, might help reduce the intensity of forest fires. By nibbling at the forest edge and on large shrubs, Sambar may help protect fynbos from being overshadowed. Van Wilgen is sceptical that Sambar provide such benefits – and he may be right. That is why research is needed.

Given that Sambar have existed on Table Mountain since the late 1890s without obvious negative effects on the mountain’s flora, the onus surely should be on SANParks (and the scientists who advise them) to provide systematic context-specific evidence as to why they should be considered a threat.

I accept Van Wilgen’s point that resources are scarce and SANParks needs to concentrate on the most important invasive species. The call for more research on Sambar need not pose an additional burden on Table Mountain National Park. Students could be encouraged to conduct studies, and volunteers asked to assist in projects such as collecting Sambar faecal pellets to assess presence, density and diet. Research does not have to be the preserve only of established scientists and over-stretched SANParks officials.

Humans and domestic animals already comprise more than 98% of Earth’s mammalian biomass. We should certainly prioritise our unique flora. But in this age of the Anthropocene, we need to protect natural systems everywhere, including novel and evolving ones.

It makes no sense to eradicate Sambar simply because they are alien and might be causing harm. We should only add to the human-induced destruction of wildlife when there is very good reason to do so. DM

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Local research lacking