Seven Year Decline of Mountain Hare Abundance in the Peak District, England

In England, the mountain hare is found only in the Peak District and is a remnant population surviving from translocations from Scotland during the 1870s of the genetically distinct subspecies <i>Lepus timidus scoticus</i>. Population monitoring undertaken by Manchester Metropolitan University and Queen's University Belfast began in 2017, continuing to 2021. Subsequently, monitoring was conducted by Natural England during 2022-2024, reporting for two sites, Bleaklow and Margery Hill, previously shown to have the highest densities of mountain hares. Standardised survey and analytical techniques remained identical to previous monitoring, enabling evaluation of change in absolute estimates of hare density from 2017 to 2024. Using distance sampling analysis, results showed a statistically significant decline of density from 2017 = 15.9 hares km^-2 (95% CI 10.4-24.4) to 2024 = 6.7 hares km^-2 (95% CI 3.9-11.5) (<i>p</i>-value = 0.0001). When stratifying by habitat class, the highest densities of hares km^-2 were found on restored blanket bog (27.9) and were statistically significantly higher than all other surveyed habitat classes: acid grassland (9.0), grouse moor bog (9.3), grouse moor heather (8.3), unrestored bog (19.3) and unmanaged dwarf shrub heath (4.0). All habitat classes showed declines; the largest were on grouse moors. For the two combined survey sites, the 2024 absolute population abundance was estimated at 542 individuals (95% CI 315-929). Extrapolating to the wider Peak District, the whole population abundance was estimated to have declined from 3562 individuals (95% CI 2291-5624) to 1038 individuals (95% CI 604-1765). Were this trajectory to continue, the mountain hare would likely disappear from England within the next few years. The causes of decline since 2017 are unknown. Lagomorph population sizes can fluctuate substantially owing to parasite mechanisms. Mountain hares persist better on restored blanket bog areas. Overall, the population is small and declining, exhibiting increased extinction risk and meriting conservation.