There are now just 3,500 mountain hares through the National Park, with estimates of 10 per square kilometre.
Research published in Ecology and Evolution today (March 31) is the result of the first comprehensive population assessment for 20 years.
Surveys involved researchers walking over 830 kilometres and observing nearly 2,000 mountain hares.
Dr Carlos Bedson, lead author of the study, said: “Our findings are deeply concerning. Whilst there are a couple of places where mountain hares are abundant, most of the Peak District hills have very few hares remaining.
“The highest mountain hare densities were in ecologically restored blanket bog, which has benefitted from investment in rewetting, where the natural flow of water is restored by blocking gullies and planting mosses and heather."
Researchers suggest such interventions, managed by partners including the Moors for the Future Partnership and the National Trust, have contributed to higher plant diversity, providing a better environment for mountain hares.
Dr Bedson said: “We have seen lifeless moonscapes of degraded bare peat revert into vibrant living landscapes that store carbon and support biodiversity providing ecosystem services, thanks to investment in bog restoration.”
Chris Dean, head of Moors for the Future Partnership, said: “While the news is worrying that mountain hares in the Peak District face an uncertain future, this study provides new evidence that our work over the past 20 years has made a positive difference, improving the habitat for this emblematic species, to give it the best chance of survival.”
The study reported fewer mountain hares on land managed for grouse shooting. Such areas are periodically burned to regenerate young heather for gamebirds. This can provide good conditions for mountain hares in some cases but seems to support fewer numbers than ecologically restored peatlands. There has also been a perceived association between ticks carried by mountain hares and disease in gamebirds, resulting in mountain hares in Scotland being culled on grouse moors. It is not known to what extent hare culling occurs in the Peak District.
Study collaborator, Dr Neil Reid, senior lecturer in conservation biology at Queen’s University Belfast, said: “Whilst it’s alarming to learn how few hares remain it’s important to remember that our research also highlights how conservation can, and does, make a difference. In this case, healthier bogs had more hares reflecting the wider benefits of rewetting peatlands. We hope these findings will lead to more rewetting of peatlands in a bid to increase not only hare population but biodiversity more generally.”
The study was funded by People's Trust for Endangered Species, Hare Preservation Trust, British Mountaineering Council, Action for Hares South West and Penny Anderson Associates. The research findings have been submitted to the Joint Nature Conservation Committee (JNCC) – the government’s advisory body on nature conservation – which has recommended that mountain hares in England are legally protected against shooting and persecution.