INFORMATION is essential to meet EU legislative conservation obligations, as well as helping manage the population, says Dr Scott Newey
Mountain hares are the UK’s only truly native lagomorph (rabbits and hares). Both rabbits and the brown, or European, hare are introduced species. The majority, probably 99 per cent or more, of the UK mountain hare population is found in Scotland, where they are widely distributed across the upland and mountainous areas. Mountain hares can be particularly abundant on areas of moorland that are managed by muirburn to create a patchwork of young and old heather, and by legal predator control aimed at promoting red grouse numbers. This management also benefits mountain hares. There is currently no formal or systematic nationwide monitoring of mountain hares and good information on their numbers is understandably difficult to obtain.
Hares are difficult to count partly because they are nocturnal – so mostly active at night and inactive during the day, when they tend to shelter in “forms” (shelters) in tall heather or other sheltered locations. They are also well camouflaged, brown in summer and white in winter. Their numbers can change rapidly and some populations show regular cycles in numbers over a ten- year period. So in the same area but in different years, there can quite naturally be very different numbers of hares. The few available sources of data on changes in mountain hare numbers suggest long term declines, but anecdotal evidence implies an increase over the last few years in their numerical stronghold in the northeast of Scotland. The reasons for any long-term changes in population are unclear, but may be related to changes in land use, climate, or due to changes in harvesting of hare populations.
Mountain hares are a traditional game species – animals that may be legally shot for sport – and they may be legally controlled to protect forestry, woodland regeneration and crops. The traditional management can involve removal of sometimes large numbers of hares from areas of managed moorland for sport and local population control, when they are at high density.
More recently, mountain hares on some moorland shooting estates have been subject to large scale culls, with the aim of reducing their numbers to low levels, for the given reason that they carry ticks which in turn carry the louping-ill virus. The virus infects red grouse and can cause high mortality of infected birds; reducing the number of red grouse that can be shot and consequently the estate income from commercial shooting. However, the scientific evidence suggests that culling hares to reduce ticks and louping-ill is unlikely to work in most situations found in Scotland because ticks are also carried by other mammals, including red deer.
Information on hare numbers and population trends is essential to meet the UK’s EU legislative conservation obligations, but this knowledge is also useful to inform the management of mountain hare populations at the local level. No simple and widely applicable methods have yet been validated for these purposes. Therefore, developing reliable methods for estimating mountain hare numbers that could be used by non-specialists across a range of hare densities, in different habitats and at different spatial scales, is a high priority for a wide range of interest groups.
Scientists from the James Hutton Institute, together with colleagues from the Game & Wildlife Conservation Trust and Scottish Natural Heritage, are collaborating on an innovative project that aims to establish and validate a reliable method for counting mountain hares, so that future population trends can be rigorously monitored and managed.
The project compares alternative methods: population estimation by live trapping, releasing and recapturing marked individuals; walking transects and counting hares; night time counts using powerful lamps and thermal imaging equipment; as well as counting their deposited dung pellets. Results are being contrasted side-by-side on the same areas over the same time period in order to calibrate and cross check them.
It is hoped that by the end of the study, the team will have produced an important contribution to mountain hare management and conservation. Clear guidelines are needed as to the most appropriate survey methods for population estimation, on which to base informed management decisions, and reporting on the fulfilment of the UK’s EU legislative conservation obligations.
• Dr Scott Newey and Professor Glenn Iason, who helped produce this article, are ecologists at the James Hutton Institute, a world-leading scientific organisation that researches crops, land, water and the environment. For more information visit www.hutton.ac.uk