A highly toxic rat poison is killing increasing numbers of birds of prey, figures show, as wildlife campaigners call for its use to be banned outdoors.
Most recently, a white-tailed eagle was found poisoned by the anticoagulant brodifacoum on an estate in Dorset. Police closed the investigation into the eagle death last week with no charges issued.
But this rare bird was not alone. New data from the Wildlife Incident Investigation Scheme shows that from 2005 to 2019, the number of dead birds of prey found where the main poison in their body was brodifacoum was in single figures each year. This changed in 2020, when 23 were found, rising from four in 2019. Twenty-five were found in the first half of 2021.
Brodifacoum is a potent anticoagulant that causes animals that ingest it to bleed internally, often for days, before dying. Experts monitoring the white-tailed eagle that died in January believe, due to its movements monitored by a satellite tag, that it suffered for days before it perished. Prior to 2016, the poison’s use outside was banned, and it was only sanctioned for use indoors, for example in food storage areas, barns and homes.
Now, it can be used outside, near buildings, and gamekeepers and landowners are cautioned to remove dead rodents in areas the poison has been applied so predators do not eat them. Unlike some other poisons, users do not get put on a register. The EU recommends it is only used in buildings, or, in severe circumstances, around them.
The rapid rise in deaths, which began four years after the rules were relaxed, has led bird-crime investigators to believe that those who wish to kill birds of prey have cottoned on to its potent impact.
“Lots of the chemicals which were around which were the most common poisons which were used to kill birds of prey were banned in recent years, and the stockpiles of these were running low,” said Mark Thomas, head of investigations at the RSPB.
He added: “Products including Ficam W, which would kill stuff instantly, were being abused to kill birds of prey. When the use of this and other poisons were restricted. It then meant that the commonest things people were using to kill birds of prey were banned or the stockpiles of them were running out.
“We suspect that somebody somewhere has worked out – when the government went out and trained people how to not kill birds of prey on estates perhaps – that this would be an effective way to kill birds of prey.”
He believes it “took the bad people a bit of time to realize the impact this newly legalized poison would have on killing birds, and you can see the results now.”
Natural England has been contacted for comment over whether its “training sessions” for gamekeepers could have inadvertently taught them how to use the poison to kill birds of prey.
A map of where dead birds with brodifacoum in their organs have been found shows that they have been poisoned in North Dorset, where there are many shooting estates, and around the North Yorkshire moors, another popular place for shooting. There have been very few incidents elsewhere in the country.
Historically birds of prey have been shot and poisoned by gamekeepers because they are thought to disrupt shoots by flying overhead and scattering the quarry, as well as occasionally eating the small birds intended for shooting.
The white-tailed eagle became extinct in the UK in the 19th century, with persecution cited as a leading factor in its demise. The large predator has now been re-introduced to the Isle of Mull in Scotland and the Isle of Wight in England.
Even if the poison is not used intentionally to kill the eagles, and other birds of prey including red kites, buzzards and hen harriers, it is known to bioaccumulate in the food chain and cause great harm, as the small rodents the poison is intended for are also the prey of these birds.
It is thought that widespread use of this poison could put the reintroduction of the eagles “in jeopardy”.
Dr Tim Mackrill from the Roy Dennis Foundation, the team that released the white-tailed eagles, said: “There is a growing body of evidence that the use of Brodifacoum presents a very serious threat to white-tailed eagles and other birds of prey, because it is highly lethal and can bioaccumulate in the food chain. White-tailed eagles are particularly at risk because carrion often forms a significant part of the diet, meaning that eagles will readily pick up poisoned rats.
“We believe that brodifacoum and other highly toxic anticoagulant rodenticides should be banned for use in external settings because their environmental risk is simply too great. Failure to do so could jeopardize the success of the reintroduction of white-tailed eagles to England, and threaten other birds of prey such as red kites.”
A government spokesperson did not answer as to whether there were plans to tighten the regulations around brodifacoum.
They said: “Current product authorizations restrict the use of SGARs [certain rodenticides] in open-areas to farmers, gamekeepers and other trained professionals and only when other integrated pest management approaches fail to control rodent populations. Some SGARs, including brodifacoum, can only be used in sewers and in and around buildings.
“Natural England in partnership with HSE are investigating the circumstances surrounding the recent incident.”