Rat poisons affect other wildlife too

POISON intended to kill rats are also unintentionally killing wildlife species, a UCT study has found.

UCT researchers in the Institute for Communities and Wildlife in Africa in their recent paper, published in the journal Science of the Total Environment, found that anticoagulant rat poisons are infiltrating Cape Town’s peri-urban wildlife food chains.

The study was conducted within and around Table Mountain National Park. Researchers identified six predator species at risk: caracal, Cape clawless otter, Cape eagle owl, large spotted genet, honey badger and water mongoose.

The study measured the presence and concentration of rat poison compounds in liver and blood samples from 41 animals, with a special focus on caracal as part of the Urban Caracal Project. At 92%, exposure to rat poisons was highest for caracals.

The predators aren’t eating the poisons directly but the poisons are designed to work on rats, who then become sick over a period of days and become easy prey for predators.

Dr Jacqueline Bishop, lead supervisor on the project, said: “We detected at least one of the four most toxic rat poison compounds, all available in over-the-counter products, in six of the seven species tested.

“Vineyards in Cape Town don’t use rat poisons to protect their vines, but they do host restaurants, spas and hotels, and occur adjacent to dense residential areas where rat poisons are widely used.

“Caracals regularly hunt in vineyards and it is here that they are likely to be exposed to poisoned rats.”

A significant finding of the study is that exposure occurs at all ages. Several lactating female caracals were sampled in the study and found to be exposed to rat poisons, suggesting that kittens may be exposed through their mother’s milk.

Collaborator Dr Nicola Okes said: “We need more eco-friendly alternatives to rat poison, and the simplest solution is to improve the management of waste which attracts rats in the first place.”