I propose to take Questions Nos. 272 and 273 together.
A national hare survey, commissioned by the National Parks & Wildlife Service (NPWS) of my Department, took place in 2018 and 2019. The project was carried out, under tender, by an experienced team of wildlife biologists and hare researchers from Queens University, Belfast. The aim of this project was to estimate the current mean population density and the national total population of the Irish Hare and to examine variation in its population across space and time (principally since the previous Hare Survey of Ireland in 2006/07).
The full report of the survey is published in an Irish Wildlife Manual on the NPWS website here: www.npws.ie/sites/default/files/publications/pdf/IWM113.pdf
The survey involved deploying static wildlife cameras in 44 x 1km survey squares. These squares were selected throughout Ireland to be statistically representative of the country’s overall habitat composition. Multiple cameras were deployed within each of the 44 survey squares. Hares were detected in 85% of survey squares. As these 44 squares were statistically representative of the national landscape as a whole this allowed the researchers to extrapolate their findings to the whole country.
There are approximately 70,000 x 1km squares in Ireland and 85% occupancy of these indicates that the hare has a very widespread distribution. The researchers’ extrapolations were further underpinned by habitat modelling which suggested that virtually every 10 km square in Ireland contains suitable habitat for the species and should be included within its Favourable Reference Range.
The inclusion of citizen science records in the survey was designed to further inform the distribution model for the species. The 1,421 Irish Hare records that were submitted by the public through the National Biodiversity Data Centre supported the results of the camera trap surveys, i.e. that the Irish hare is very widespread in Ireland. These records were not used, however, in the population model which was solely based on the standardised sampling of the camera trap survey.
Using the camera trap data, methods were developed to estimate the distance of each hare detected on camera, enabling the use of distance sampling analysis. Distance sampling is a statistical package developed specifically to estimate the densities of wild animals.
Mean Irish Hare density during winter 2018/19 was estimated at 3.19 hares per km2 (95% confidence intervals: 1.59–6.43) with highest and very comparable densities in the northwest (3.50 hares/km2) and southwest (3.46 hares/km2) regions and lowest density in the east (2.66 hares/km2 ).
The average estimate was 4.5% lower than the 3.33 hares/km2 estimated during 2006 and 58% lower than the 7.44 hares/km2 estimated during 2007. Nevertheless, such was the width of the 95% confidence intervals that the current density estimate cannot be said to be significantly lower than the previous survey. It should also be noted that hares are known to show significant, natural inter-annual fluctuations in population (as demonstrated by the 2006/2007 data).
The mean density estimate from this latest national survey was comparable to the 20 year mean density from all surveys since 2000 of approximately 3 hares/km2 . This suggests that the population remains stable. The national Irish Hare population was estimated at 223,000 individual hares during 2018/19 (with a 95% probability that the number is between 111,000 and 449,000). The other figures provided in Table 7 of the report and referenced in the question (the Bootstrapped Confidence Intervals) are indicative of the extreme limits of statistical possibility and both the lower limit (60,095) and the upper limit (1,197,709) are considered to be highly unlikely.
