The Himalayan Tahrs of Table Mountain
Have you ever seen a peculiar, goat-like mammal trotting the slopes of Table Mountain? If so, you’ve stumbled upon the infamous Himalayan Tahr (Hemitragus jemlahicus), a large ungulate (“hoofed animal”) native to Northern India, Southern Tibet, China and Nepal (ref).
The story of how these exotic, ‘wild goats’ found themselves on Table Mountain is a colourful one. Way back in the 1930’s, nestled on the slopes of Table Mountain near the University of Cape Town, was the Groote Schuur Zoo. It covered two hectares of land and had numerous animals such as lions, crocodiles, emus and tahrs – two of which managed to escape (ref).
Once roaming free, a number of factors led to the success of the Himalayan Tahr as an invasive species. Firstly, there are enough similarities between Table Mountain and the tahr’s natural Himalayan habitat – typically steep, rocky mountain cliffs flanked by woodland and scrub (ref). Secondly, the scarcity of predators on Table Mountain (compared to predation by the Snow Leopard in its native territory) has meant that tahr population growth was limited only by access to food and water, and its own reproductive rate (ref). A third contributing factor has been the tahr’s flexible digestive system, which has enabled it to feed on a wide variety of vegetation. This, coupled with the animal’s capacity to be extraordinarily mobile has supported its constant access to food and water resources (ref).
The result is that we have a substantial population of tahrs on Table Mountain today. Fascinating as these shaggy mammals may be, however, their exotic nature poses serious challenges for the natural biodiversity and fragile ecosystem of the mountain. They contribute to loss of endemic plant life and soil erosion through heavy foraging and over-grazing, and their aggressive species presence threatens that of the klipspringer, an indigenous, ‘rock-hopping’ antelope that has been reintroduced to the region (ref).
With these issues in mind, culling programmes have been carried out by Cape conservation authorities in the past, but have been strongly contested by many of the Cape’s residents.
An alternative solution to the conundrum could be to capture these animals in nets released from helicopters, before quarantining and transporting the tahrs safely to their natural Himalayan habitat. This method has already been used to catch and relocate numerous tahrs in New Zealand, where a similar issue exists (ref). But this method is by no means without its challenges: as the animals move incredibly quickly across steep rock banks and cliff faces, tracking them is a dangerous undertaking for helicopter pilots, and the tahrs also run the risk of falling accidentally from the cliffs as a result of the intervention.
While the vital threats posed by Himalayan Tahrs to Table Mountain’s ecosystem should be seriously heeded and some form of action must be taken, the sad irony of the matter is that there are very few tahrs left in their natural Himalayan habitat. The species is listed as ‘Near Threatened’ on the IUCN Red List (ref) due to habitat loss and hunting.
Photo credits: Alistair Pott