Most of Cape Town’s caracals have rat poison in their bodies. The discovery, reported in Environmental Pollution, raises concerns about the hidden effects of rodent control on wildlife, and calls for tighter regulation of these chemicals.
Caracals are wild cats native to Africa and parts of the Middle East and Asia, instantly recognisable by their long, tufted ears.
The nocturnal cats typically feed on birds, rodents and other small mammals. In urban areas, this creates a problem because caracals can encounter rodents that have eaten anticoagulant poisons. The chemicals prevent blood clotting and can cause fatal internal bleeding.
Researchers analysed the livers of 102 caracals that had died, mainly in road collisions, and found that 78% of the samples contained rodent poison.
Most individuals were exposed to at least three different compounds, but some had up to six compounds in a single sample. Older animals had higher burdens, suggesting that the cats are being exposed to the chemicals repeatedly over time.
The compounds were dominated by second-generation anticoagulant rodenticides, which are more potent and persistent than their first-generation predecessors. A poisoned animal can take up to two weeks to die, during which time rodents may continue feeding and carry high concentrations of the chemicals, potentially exposing non-target predators and scavengers.
“Caracals are red warning lights at the top of the food web,” says Gabriella Leighton from Stellenbosch University, South Africa. “Caracals move easily through natural areas, farms and suburbs and eat many kinds of prey. What accumulates in their bodies provides a broader picture of contamination across the landscape.”
Although caracals rarely die from eating poison-laced rodents, conservationists are worried that sublethal doses could be harming the cats. Studies on North American bobcats have linked exposure to rodent poisons with inflammation, poor immune system functioning and greater disease susceptibility. We don’t know if caracals react in the same way, but the high levels of exposure suggest cause for concern.
The researchers say the problem may be exacerbated by the widespread availability of anticoagulant rodenticides in South Africa. Dozens of products containing these chemicals are sold in supermarkets, hardware stores and online, meaning they can be used by members of the public as well as pest-control professionals.
Now, they are calling for tighter controls on the sale and use of the most toxic second-generation poisons, with access restricted to trained pest-control operators. They also recommend reducing the need for poison by securing food waste, sealing buildings against rodents and using traps instead.
Top image: A caracal hunting a rat in Kirstenbosch National Botanical Gardens, Cape Town, South Africa, where they have been found to be exposed to high levels of rat poisons. Credit: Jacque Smit
More wildlife stories from around the world
- 61 black mambas captured in African city. Here's what experts found in their scales – and why it matters
- When lions raided wild dog dens in Botswana, wildlife guides didn’t expect to see this
- An army of giant rats are being trained to sniff out animal body parts. Here's why
- Family of super-rare black-and-white monkeys spotted in remote mountains of Vietnam
- Crocodile attacks lion cub on Zambian river. Here's how its pride reacts
