Capercaillie numbers have slumped in Scotland – the only part of Britain where the world’s largest grouse breeds – and are now so low that the species could again face national extinction.
Pine martens, badgers and other generalist predators eat capercaillie eggs, so some people suggest that killing martens could help capercaillie.
Yet evidence that this would help to boost the big grouse is poor. Both species are also legally protected in the UK, with pine marten numbers only recently increasing after a long history of persecution by humans. It’s part of a common dilemma for people trying to restore healthy populations of both predators and prey: how to live and let live.
That’s the case within the Cairngorms National Park, both a good place for pine martens and now the last significant Scottish refuge for capercaillie. Almost all of them live in pinewoods to the west of its central mountains. With just over 500 birds remaining, the situation is grim.
But results from a recent experiment give grounds for optimism about coexistence of both capercaillie and martens.
From late April to early July in 2021 and 2022, PhD researcher Jack Bamber from the University of Aberdeen’s School of Biological Sciences led research to see if providing alternative food for predators could shift their attention from capercaillie nests.
Fake nests placed at widely separated forest locations were made to mimic capercaillie nests in size, siting and appearance, including natural covering reminiscent of a female capercaillie’s plumage.
Hen eggs looking like capercaillie eggs were put in each nest, plus a wax-filled egg, tethered so that marks from teeth, claws and bills could help to ID egg thieves.
Half the nests had carrion from deer carcasses placed in their vicinity, the other half did not. Findings were clear: an 83 per cent increase in survival of nests in places where carrion was provided.
“This suggests that reducing nest predation through diversionary feeding could contribute to more successful capercaillie breeding,” says Jack Bamber.
“Importantly, diversionary feeding of pine martens and badgers at key times of the year can achieve positive conservation outcomes without lethal control of protected predators.”
Read more about the research.
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