It’s 9pm in late April in an area of the Isle of Man known as the Ballaugh Curragh, and a most unusual nocturnal migration is taking place. As darkness descends on a 2km² area of wet woodland, an estimated 600 red-necked wallabies are emerging to feed on the surrounding grasslands.
You’d think that 600 wallabies would be easy to spot as they awake from their daytime slumbers, especially since the island has no large native land mammals to confuse them with. But as the Manx Wildlife Trust’s head of conservation David Bellamy points out, they blend in well with the tangled, swampy forest of grey willows.
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“The fact that four of us, who are looking for wallabies, just walked past one without seeing it and it’s only 15m away highlights how easy it is to be here and not realise you are surrounded by them,” he says. (It’s only spotted with a thermal-imaging camera.)
The wallaby controversy
It surely goes without saying that the wallabies should not be on the Isle of Man, and especially not in the Ballaugh Curragh, the island’s only Ramsar site and area of special scientific interest. The macropods are native to mainland Australia and Tasmania, but they were brought to the government-owned wildlife zoo in 1965.
Shortly afterwards, it seems, a few wallabies escaped (no one knows how many but it was probably fewer than 10), and they’ve been living as a feral population ever since. Until a couple of years ago, it was assumed the total population was fewer than 100 animals. But in 2023 and 2024, two surveys using drones enabled with thermal-imaging cameras blew this assumption far out into the windy Irish Sea.
Instead of dozens of wallabies as had been believed, a staggering 870 individuals were counted in the north of the island alone, and it’s now believed there are somewhere between 950 and 1,150 animals living wild. Because they are all descended from a handful of individuals, they are almost certainly inbred, with some individuals suffering from afflictions that leave them with milky white eyes and probably blind. These same animals are described as appearing disorientated.
Arguably more urgent are the impacts the wallabies are having on the Isle of Man’s native wildlife, and farmers’ fears they could spread diseases to their livestock. Everyone agrees that something has to be done but no one wants to use the word ‘cull’, not least because the wallabies have become embedded within Manx national identity and are a tourist attraction, too.
“They divide opinion,” says Philip Jenkins, who runs a tourist accommodation business on the island. “We always tell our guests to go and see the wallabies, but I wouldn’t say they bring people to the island. It’s a government location they escaped from, and it needs to do a proper study and work out what the best course of action is.”
Leigh Morris, who was the Manx Wildlife Trust chief executive until May, says the drone survey is changing the way islanders see this species, which until now had been viewed as harmless. “I had a very pro-wallaby person in my office, and they were saying there weren’t that many of them and asking why we were stirring this issue up,” he says. “So I showed them the drone footage and they said, ‘There’s 62 in one field!’”
Impact on native wildlife
The trust is now starting to ask itself some hard questions about just what impact the incomers are having. Certainly, in the Ballaugh Curragh, where they are most densely concentrated, there have been some devastating losses.
It used to be home to a huge winter hen harrier roost, for example, which at its peak hosted 160 birds, the largest in Europe – but they have completely disappeared. (There are still nearly 40 breeding pairs every year, a number that has remained broadly static in recent years.) Corncrakes have also gone and curlews are only just holding on.
These are three very different species but they have one thing in common – they are ground-nesting and ground-roosting, and so especially vulnerable to disturbance. “I think a hen harrier roost and a large wallaby population are incompatible,” says Bellamy. “The hen harriers want zero disturbance, and the wallabies are quite clumsy animals, crashing around and making a lot of noise.”
The Isle of Man government is more concerned about whether the wallabies have the potential to spread disease to livestock. “The issue of the wallabies has come up in a number of different areas,” says the environment minister Clare Barber. “There’s the wildlife perspective and our Biosphere status, but we also want to look at the biosecurity risks and the risk to livestock, domestic animals and human health.”
With this in mind, Dr Arno Wuenschmann, a professor of veterinary pathology from the University of Minnesota, was asked to carry out postmortems on three wallabies. (Wuenschmann became involved partly because of his expertise, but also because he is a frequent visitor to the Isle of Man himself.)
The most eye-catching of Wuenschmann’s findings was of the toxoplasmosis parasite in the brain and eye of one of the wallabies. Toxoplasmosis is a common wildlife disease in Europe and is also carried by domestic cats, who act as an intermediate host.
An estimated 10–30 per cent of the UK population has been infected with this pathogen at some point in their lives, but it has no impact on most healthy people, with the exception of pregnant women, where it can cause miscarriages, stillbirths and congenital defects in offspring.
But toxoplasmosis is not native to Australia, and wallabies have not evolved to live with it, so they may be affected to a much greater degree. “They will have a susceptibility to toxoplasmosis that native wildlife doesn’t,” says Wuenschmann. “It’s not a surprise we found it but it may explain some of the neurological signs that have been reported.”
Wuenschmann also found evidence of a gastric worm that is only found in wallabies and kangaroos, and which you would expect to see. It’s possible, he says, they are impacted by some combination of their lack of genetic variability, toxoplasmosis and the gastric worm, but to be really certain of what’s going on, he says, they need to examine more animals.
“It’s for somebody else to decide what you want to do about it, if anything,” Wuenschmann adds.
The future of Manx wallabies
Leigh Morris is aware that the public, and the trust’s members, might not take kindly to the idea of managing the number of wallabies. “Disappointingly, we had a few people criticise us for killing ‘long-tails’ (what Manx people call brown rats) to protect the shearwater population,” he says.
Bellamy says a national conversation needs to take place and, though the wallabies’ impact on native wildlife is clearly negative, he acknowledges there will be no appetite for eradicating them entirely. “I do think one day we will accept that, for the welfare of the animals themselves, for farmers, for road safety and for ecological reasons, we should bring the population down to a manageable number,” he says.
“We might say we don’t want them in the south of the island and we don’t want them in the hills – the Ballaugh Curragh may be okay for some, but we need a level of containment.”
Elsewhere in Britain, multiple species are culled for ecological reasons – rats on islands to safeguard seabirds, American mink to protect water voles, and both native and non-native deer for the good of our woodlands – but the Isle of Man has not had to make such hard decisions. It does now.
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Top image: wallabies in the Curragh Feeagh nature reserve on the Isle of Man. Credit: Getty
