Capercaillies benefit when their predators are treated to a free meal. Research in Proceedings of the Royal Society B shows that the practice of diversionary feeding, which involves leaving food out for problem predators, boosts the breeding success of these iconic forest birds.
The capercaillie is a large, chunky woodland grouse. Males, which have an impressive, fanned tail, come together in leks to display to the females and vie for their attention. In the UK, they breed in the native pinewoods of northern Scotland, but numbers are low. With just 500 birds left in Scotland, the capercaillie is on the UK Red List of threatened species.
Habitat loss and collisions with deer fences are partly to blame, numbers also suffer when predators, such as pine martens and badgers, eat the capercaillies’ eggs and chicks.
So, researchers designed an experiment to see if diversionary feeding can help. They divvied up portions of the birds’ range in the Cairngorms National Park, into 'extra food’ sites, where they left out chunks of deer meat for the pine martens and badgers to eat, and ‘no extra food’ sites, where they left well alone. Then they used remote cameras to monitor the capercaillie’s nests and see what happened next.
85 per cent of the capercaillies in the ‘extra food’ sites went on to have chicks, compared with 37% of the capercaillies in the ‘no extra food’ sites. Diversionary feeding increased the chances of a bird starting a family.
In addition, their broods were also bigger. The number of predicted chicks per hen was 0.82 in the ‘no extra food’ sites and 1.9 in the ‘extra food’ sites – an increase in capercaillie productivity of 130%.
The strategy worked. The team found a way to help the capercaillies without negatively impacting the pine martens and the badgers, which are both protected species.
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“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 Jack Bamber from the University of Aberdeen.
Diversionary feeding carries the risk of boosting predator numbers, which could backfire in the longer term if it makes the predators to go after the capercaillies again. To minimise this risk, the deer carrion was only left out for short chunks of time during the birds’ breeding season. Now the team hope the same strategy can be rolled out to help protect capercaillies living elsewhere in Europe.
Top image: capercaillie. Credit: Getty
