What a time to be alive…if you’re a capercaillie! The average brood size of the birds has more than doubled in parts of Scotland, a study in Proceedings of the Royal Society B reveals, all thanks to a gentle anti-predator management scheme.
Weighing more than the average building brick, capercaillies are the world’s largest grouse species. The males are known for their large, fan tails, and for their leks, where they gather together and show off by making clicking and whistling sounds to impress the females.
Over the last ten years, numbers of the bird, which is found in the pine forests of the Scottish Highlands, have almost halved. Now there are just 500 left in the wild, and in the UK, the capercaillie is at risk of extinction.
Habitat loss and fragmentation are to blame, as is increased predation by pine martens and other species. So, conservationists have a problem. How to stop the predators eating the capercaillie’s eggs and chicks, without negatively affecting predators?
The answer, Jack Bamber from the University of Aberdeen and colleagues have found, is to provide the predators with an easy, alternative meal.
Every breeding season, from 2021 to 2023, the team left out big chunks of deer carrion at specific sites in the Cairngorms National Park. In control sites, they left no extra food. Then they monitored the capercaillies’ nests with camera traps and waited to see what happened.
As expected, the local pine martens and badgers readily feasted on the free meals that were provided. In these areas, capercaillies were more likely to have a brood. 85 per cent of birds in the ‘fed’ sites had chicks, compared with 37 per cent of birds in the ‘unfed’ sites.
Their broods were bigger too. The number of predicted chicks per hen was 0.82 in the ‘unfed’ sites and 1.9 in the ‘fed’ sites – an increase in capercaillie productivity of 130%.
‘Diversionary feeding,’ as it is called, worked. “This study provides compelling, robust, landscape-scale evidence that diversionary feeding can reduce the impact of recovering predators, without killing them, aligning with shifting ethical and ecological goals for conservation management in the UK,” says Bamber.
By feeding over a short, timed, eight week window, the capercaillies benefit and there is no boom in predator numbers. Now the team think their strategy could be used to help capercaillies in the southern part of their range, such as Cantabria, the Alps and Bavaria.
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