Populations of the black-footed cat, a little-known feline in Southern Africa, have been declining for the last half a million years and exhibit very high degrees of inbreeding. This could increase their risk of a disease called amyloidosis, according to a new genetic study.
“Frequently genomic studies focus on large charismatic cats so that small species, especially the very small black-footed cat, are neglected,†says study author Andrew Kitchener, principal curator of vertebrates at National Museums Scotland. “However, all species have interesting stories to tell and the black-footed cat is no exception.â€
Weighing about as much as a large pineapple, the black-footed cat (Felis nigripes) is one of Africa’s smallest, rarest and, arguably, most endearing cats. They’re only found in arid steppe and grassland savannas in Southern Africa, including Namibia, South Africa and Botswana. The IUCN Red List categorizes them as vulnerable to extinction.
Like many other threatened species, the black-footed cat is under pressure from habitat loss and degradation, as well as climate change. But there’s another worry too: about 70% of captive black-footed cats die of amyloidosis, a fatal disease associated with deleterious genetic mutations and believed to be inherited. Wild populations are also susceptible, though the mortality rate is nearly impossible to determine.
Over the past few decades, researchers have learned a lot about the cat’s conservation needs, thanks to long-term field studies in South Africa and Namibia. Black-footed cats — handsome tawny predators with black spots and stripes that almost pass in looks for domestic cats — are extremely successful nocturnal hunters with voracious appetites, eating a fifth of their body weight in prey each night. Mortality rates are high, with nearly 40% of the studied populations dying each year, mostly due to predation and disease, says Alexander Sliwa, project leader for the Black-footed Cat Working Group and curator at Cologne Zoo. But until now there’s been very little research on their genetics.
To redress that imbalance, Kitchener and fellow researchers began by generating the black-footed cat genome from a number of reference samples. They then combined this with previously published genomic data for the species and compared this with the genomes of other small cat species.
The study shows that the black-footed cat branched off from the Felis genus about 3 million years ago, making it one of the most ancient small cats. There’s evidence of subsequent hybridization with ancestors of the jungle cat (Felis chaus), sand cat (Felis margarita) and wildcat (Felis silvestris). The researchers also traced the selection of genes that help make the black-footed cat such a successful hunter, including those associated with the ability to track fast-moving objects, acute hearing, and a high metabolic rate that allows them to keep active on cool nights.
But the analysis also shows that the black-footed cat population has been declining over the last half-million years. The researchers found a worrying degree of inbreeding, and, in some measurements, even lower levels of genetic diversity than some of the big cats like lions (Panthera leo) and jaguars (P. onca). These high levels of inbreeding are likely due to historic and contemporary habitat fragmentation, the authors write, and may increase the risk of the fatal disease amyloidosis, which is known to have a genetic basis.
Sliwa, who wasn’t involved in the study, says it addresses a real paucity of genetic studies on small cats, adding that future studies with larger sample sizes from more geographic areas would be good to see.
Today, black-footed cat populations face myriad threats, including land-use change, habitat fragmentation, climate change, and disease. In Sliwa’s long-term black-footed cat study sites in South Africa and Namibia, the impacts are alarming.
“I currently really have a total crash of the population in my study areas,†he says.
In 2023 and 2024, Namibia experienced its worst drought in a century, in part fueled by El Niño and climate change. Over the next century, such droughts are likely to become more frequent and severe, according to climate change projections.
Sliwa notes that in his study area in southern Namibia, there’s been practically no rain in the past two years. The area has always been close to the limits of what the black-footed cat can tolerate in terms of aridity. Now, the drought is pushing the cats out of their favored short-grass habitats and into the riverbeds, which puts them into closer contact with farmers and their dogs. The dual threat of starvation and being killed by dogs meant that last year, all of Sliwa’s study animals died.
The black-footed cat’s world is changing in other ways too. Humans are driving many large carnivores toward extinction, meaning that lion, leopard (Panthera pardus) and cheetah (Acinonyx jubatus) populations have declined or disappeared across much of the black-footed cat’s range, with medium sized predators taking their place. In Sliwa’s study areas, that means more caracals (Caracal caracal) and black-backed jackals (Lupulella mesomelas), both of which kill black-footed cats.
“We’re talking about two very generalized predators against one highly specialized one,†Sliwa says. “And those two, caracal and black-back jackals, are the main predators of black-footed cats, so we lose at least 30% [of the cats] to them in terms of predation.â€
Sliwa also sees the impact of amyloidosis on the wild population, but says it’s hard to figure out how much of overall mortality is attributable to the disease.
Amyloidosis is a disease where abnormal proteins are deposited in organs or tissues. In wild black-footed cats, the first sign is excessive thirst. Black-footed cats usually get all the liquid they need from the blood of their prey. But as those abnormal proteins affect the kidneys, the sick cat will start going to standing water. Once that happens, the cat will usually be dead within a month, Sliwa says, either because it dies outright from the disease or because it becomes increasingly disoriented and is then an easier target for predators.
“So, for us, it’s quite difficult to distinguish,†Sliwa says. “Was that pure predation because the animal wasn’t watching out, or was that animal already sick and then been taken?â€
The combination of threats means that whole populations can disappear, an outcome that Sliwa and colleagues are working hard to prevent.
For the black-footed cat and other threatened species, understanding the genetic susceptibility to disease is important, Sliwa says, but on its own isn’t enough to conserve wild populations. For that, you need field data and funding to support conservation work on the ground, he adds.
Citations:
Lai, S., Warret Rodrigues, C., O’Donnell, H., Küsters, M., Herrick, J., Lawrenz, A., … Sliwa, A. (2024). Assessing the effect of predator control on blackâ€footed cat survival in central South Africa. African Journal of Ecology, 62(3), e13316. doi:10.1111/aje.13316
Sliwa, A., Lai, S., Küsters, M., Herrick, J., Lawrenz, A., Lamberski, N., … Wilson, B. (2022). Causes of mortality in a population of black-footed cats in central South Africa. African Journal of Ecology, 60(4), 1311-1317. doi:10.1111/aje.13033
Yuan, J., Kitchener, A. C., Lackey, L. B., Sun, T., Jiangzuo, Q., Tuohetahong, Y., … Li, G. (2024). The genome of the black-footed cat: Revealing a rich natural history and urgent conservation priorities for small felids. Proceedings of the National Academy of Sciences, 121(2), e2310763120. doi:10.1073/pnas.2310763120
This article by Ruth Kamnitzer was first published by Mongabay.com on 28 October 2024. Lead Image: A male black-footed cat stalking prey in winter 2019. Black-footed cats eat mostly small mammals and birds. Their keen sight and agility mean they are extremely successful hunters. Image courtesy of Alexander Sliwa.
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