Single Species Schemes

The Vincent Wildlife Trust Polecat and Mink Abundance Monitoring

Run and funded by The Vincent Wildlife Trust (VWT)

Run by Quercus (Queen's University Belfast), funded by Northern Ireland Environment Agency (NIEA) and the National Parks and Wildlife Service in the Republic of Ireland.

The Irish hare (Lepus timidus hibernicus) is an endemic subspecies of the Mountain hare (L. timidus). It differs markedly in phenotype, behaviour and ecology from mountain hares elsewhere and recent genetic research suggests that it is sufficiently distinct to warrant full species status as Lepus hibernicus (Hughes et al. 2006).

Game bag records suggest that Irish hare populations were considerably larger during the mid-19^th to early 20^th century than at present (Reid, 2006). The initiation of Irish hare population declines started during the early 20^th century, synchronous with changes in land management practices associated with early agricultural intensification.  Gamebags declined continuously from 1914 to 1970 (Reid, 2006).

Direct counts of Irish hares recorded during day-walked transects during the Northern Ireland Rabbit Survey (1986-1995) suggest that the Irish hare population continued to decline throughout the latter half of the 20^th century (Reid et al. 2007).

The Irish hare attracted major conservation concern after work carried out during the mid-1990s that suggested mean densities had dropped to a low of 0.65 hares per km² throughout Northern Ireland (Dingerkus & Momtgomery 2002). A Species Action Plan was prepared with targets in line with the Brown hare SAP under the UK Biodiversity Action Plan. The Irish hare Species Action Plan highlighted the necessity for a system of regular, cost-effective monitoring surveys to be put in place.

Since 2002, Quercus have conducted annual late winter/early spring night-driven surveys using conventional distance-sampling to assess temporal changes in hare population densities across Northern Ireland. These surveys tentatively suggest that the hare population has increased since the mid-1990s and stabilised at relatively low densities compared to those likely during the 19th century.

During 2006/07, Quercus also conducted a hare survey throughout the Republic of Ireland. New field methods and statistical analyses were developed in collaboration with RUWPA at the University of St. Andrews to increase the accuracy and precision of distance derived density estimates. New custom-made distance analyses suggest that conventional models may underestimate densities by 50-70%. During 2007, densities were estimated at 7.66 hares per km², a number twice that recorded during 2006 suggesting that the Irish hare population is robust enough to undergo an apparent doubling within one year given favourable climatic conditions. Using custom distance-sampling and taking Northern Ireland and the Republic of Ireland together the total hare population of Ireland during 2007 was estimated at 649,000 hares.

All time-series that exist for the Irish hare exhibit substantial interannual fluctuations. Historical gamebag records also exhibit complex multiannual periodicity.  Whilst the mechanisms driving long-term fluctuations remain unclear, delayed density dependence, weather conditions and climatic oscillations have all been implicated. Thus interpretation of short-term changes should be avoided.

Survey method: All surveys use spotlight night-driven line transects along which hares are detected at points spaced 200m apart. Annual Northern Ireland surveys use conventional distance analyses to yield fully comparable estimates between years; however, the Republic of Ireland survey used custom-developed distance analysis that was not comparable to previous methods. The latter suggests that conventional distance analysis is not appropriate to estimate hare densities in the Irish landscape and is likely to result in negatively biased estimates. Nevertheless, standardised surveys of Northern Ireland are likely to describe relative temporal change.

Site coverage: The Northern Ireland survey utilities 8 long-line transects each 100km in length with at least one in each County. In contrast, the Republic of Ireland survey utilised almost 1000 short-line transects each 1km in length spaced every 10km to given uniform coverage.