Pests on the pill: a new method of wildlife control

The deer population could be controlled by oral contraception. Picture: Stephen Collins/Collins 

The invention of the contraceptive pill heralded the sexual revolution of the 1960s, and now scientists are looking to revolutionise wildlife control by getting animals in on the action.

Trials are under way in the UK and elsewhere in Europe on how to get contraceptives into pigeons, wild boar and grey squirrels, with scientists also proposing other rodents, invasive parakeets and deer as other target species.

Pigeons could be fed a 'breakfast' of corn grains containing the contraceptive every morning. Picture: Leah Farrell/Rollingnews.ie

As destruction from invasive and pest species grows, researchers are looking to fill special feeders and bait boxes with hazelnut spreads and grains laced with contraceptives. They believe this could be a more humane and effective way of controlling populations that have previously been poisoned, shot or trapped.

The aim is to find “creative solutions”, says Dr Giovanna Massei from York University. 

“The main message is that the economic and the environmental impact of wildlife are increasing worldwide, and we are running out of options. 

Traditional methods such as culling are ineffective, can be inhumane, unsustainable, environmentally harmful, and are increasingly opposed by the public.

Trials are under way to deliver oral contraceptives hidden in a hazelnut spread for squirrels in the UK, using specially weighted feeders that only grey squirrels can open. Preliminary results suggest the method is working.

Pigeons could be fed a “breakfast” of corn grains containing the contraceptive every morning, said Dr Marco Pellizzari, a veterinary consultant.

Across continental Europe and Scandinavia, there has been a rapid increase in wild boars, with the rise in numbers believed to be linked to milder winters.

Across continental Europe and Scandinavia, there has been a rapid increase in wild boars, with the rise in numbers believed to be linked to milder winters. Some consider them pests because they root up cropland, munch through rubbish and cause traffic accidents. 

Italian farmers’ associations say the wild boar population doubled from 500,000 in 2010 to one million by 2020. In Germany and in France, more than half a million are shot every year, but numbers are increasing, and the number of people who want to hunt them is declining.

A pilot programme is under way to look at giving them contraceptives using devices that only boar can lift up, using their burrowing snouts.

Many countries are now banning the use of rodenticides because of their impact on other animals, including birds of prey, which have died from eating the poisoned carcasses. The chemicals are also considered inhumane. 

Guardian