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Prioritising mitigation sites for otters Smallbone W, Wilkinson C and Chadwick E www.otterproject.cf.ac.uk. 2. Methods (Fig. 3) Trunk Roads Agencies Wales funded Cardiff University Otter Project (CUOP) to identify priority sites for mitigation in Wales
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Prioritising mitigation sites for otters Smallbone W, Wilkinson C and Chadwick E www.otterproject.cf.ac.uk • 2. Methods (Fig. 3) • Trunk Roads Agencies Wales funded Cardiff University Otter Project (CUOP) to identify priority sites for mitigation in Wales • Data collated from CUOP and Environment Agency (1992 – 2011) • Potential mitigation sites prioritised based on multiple mortalities; evidence of breeding highlighted • Introduction • Since declines in the 1950s-70s, otter populations have increased • Population increase, expansion of road networks and increasing traffic = road mortalities • UK BAP proposes to limit accidental killing / injury of otters through mitigation, e.g. ledges (Fig. 1) / dry culverts (Fig. 2) and appropriate fencing • For mitigation to be effective, priority sites must be suitably targeted Geoff Liles Fig. 1 – Otter ledge at Pont Dolau, Wales Jean Matthews Fig. 2 - Dry culvert at Neath Morfa Glas Otters found dead - location (NGR) and date recorded • 3. Results – otter mortalities in Wales • 785 mortality sites (Fig. 4) • 129 multiple mortality sites • 29 sites designated high priority (5 or more casualties within 2km on same road since 2000), e.g. Fig. 5 • 11 sites designated medium priority (4 casualties within 2km on same road since 2000), e.g. Fig. 6 • Resulting reports for North, Mid and South Wales available from www.otterproject.cf.ac.uk/mitigation.html Post mortem - Sex, reproductive status, age-class and cause of death Clusters identified using ArcMap GIS Count of road casualties within 2km, on same road, since 2000 -≥5 = high, 4 = medium priority sites designated Fig. 5 -High priority site in mid Wales (fifteen otter mortalities including 6 on the A40 since 2000) Fig. 3 - Method of data collection and site prioritisation Fig. 4 – Otter casualties in Wales from 1992-2011 • 4. Recommendations • Priority sites should be individually assessed by experienced surveyor - mitigation may not be appropriate / possible at all • Opportunities should be taken to install mitigation for otters (and other wildlife) wherever road construction / improvement is undertaken • Records of existing mitigation should be collated and success / failure monitored Figure 6 - Medium priority site in North Wales (five otter mortalities including 4 on the A55 between 2009 and 2010)