The chance of seeing a wolf is one of the eco-tourist attractions in Asturias, a beautiful, mountainous region on the northwest coast of Spain. Not so happy is to see dead wolves or their heads hanging from traffic signs, as some Asturians press their local politicians for continuing permission to shoot the animals.
The European Wilderness Society mourns the “dozens” of wolves shot each year from a population of some 250. And it claims “a web of deceit” in false claims by farmers for compensation for wolf attacks on livestock.
The Spanish story, however, could encourage supporters of “rewilding” here with wolves. The Asturias animals hunt and kill the wild boars of the woods, many of them infected with TB.
Research led from America’s Heriot-Watt University studied the densities of wolves and boar, and the prevalence in boar of infection with bovine TB. They also measured the costs of the disease in cattle and compensation for wolf attacks on livestock.
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They found that the attacks on the boar reduced the rate of TB, which rose again when wolves were absent — this without affecting the overall density of boars. It also reduced the “spillover” of TB into cattle. Indeed, the costs of compensation were more than covered by the savings on cattle.
Dr Paddy Sleeman, the UCC mammalogist long involved in Ireland’s problems with bovine TB, calls this “the very definition of cost-effectiveness”. But he also sees the Asturias study as expressing a ”universal lesson” in ecology — “that predation can provide the ecosystem service of disease control”.
Writing in the RTÉ online feature Brainstorm, he cites other examples, such as studies of wolf predation on moose in the US. They select adult moose a large, water-loving deer, suffering from osteoarthritis, or even with a genetic tendency to get it: “Again, the predator controls the disease.”
There is also the case of Ireland’s native pine marten. Restored from near-extinction, it preys selectively on alien grey squirrels. These carry a squirrel pox that can be fatal to red squirrels. Where greys have disappeared, the population of reds is now increasing.
Humans, says Sleeman, are the most destructive predator on earth, eliminating, unselectively, much of the planet’s megafauna. “All this allowed us to live at high densities in towns and cities, but with long-term health implications.”
Sleeman has been engaged for decades in field studies of badgers and the successful use of vaccination to reduce their carrying of bovine TB. But his Brainstorm piece does not engage with the thought that will occur to some of his readers. Would restoring wolves to Ireland reduce the number of infected badgers and their “spillover” of TB to cattle?
An online check of wolves and their prey is not all that supportive: badgers are rarely on the menu. Aggressive adult badgers have no natural predators on these islands. In Europe, their cubs may sometimes fall prey to wolves, and badger has shown up in droppings in Finland, Italy and China.
The favourite prey of a wolf pack, however, are deer, and Ireland’s Sika deer are now positively linked to local outbreaks of bovine TB. While TB infection rates, in general, have been falling, helped by badger vaccination, higher local TB has been correlated with higher numbers of the deer, now known to be new maintenance hosts of the disease
The research, conducted by Trinity College Dublin and the National Parks and Wildlife Service (NPWS), was recently published in Frontiers in Veterinary Science.
As lead author, Dr David Kelly of TCD says Sika deer are of greatest concern in Co Wicklow but the national surge in the deer population may pose problems elsewhere. Sika are already indicted for their bark-stripping damage to forestry.
The ‘rewilders’ are in straight conflict with the NPWS which is determined to eradicate wild boar
The call for wolf reintroduction in key mountain areas of Ireland, such as the Wicklows, those of Kerry and the “rewilded” Nephins in north Mayo, has been backed by Green Party leader and Minister for Climate Eamon Ryan and Pádraic Fogarty of the Irish Wildlife Trust.
Fogarty is also an enthusiast for restoring wild boar to the forests. In his book Whittled Away: Ireland’s vanishing nature (2017), he cites Sleeman’s conclusion that without the wild boar in post-glacial Ireland, the island’s 2,000 or so wolves would have had nothing to eat.
In this enthusiasm, the “rewilders” are in straight conflict with the NPWS which is determined to eradicate wild boar. These were mysteriously reintroduced some years ago and are officially feared as an “invasive alien” with the potential risk of carrying a deadly swine disease (if not, so far, of catching bovine TB).
The NPWS has appealed to the public to report any sightings of boar. Last summer, a substantial family was seen roaming the woods of Co Kerry. The sow and her young were promptly “culled” by a marksman team, which then pursued and killed the large and fast-moving father.