Turning back the tide of American mink invasion

19 November 2012

Turning back the tide of American mink invasion at unprecedented scales in partnership with communities: benefits and limitations of volunteer-based invasive management

Presented by: Professor Xavier Lambin, School of Biological Sciences, University of Aberdeen

Successful eradications of harmful invasive species have been mostly confined to islands while control programs in mainland areas remain small, uncoordinated and vulnerable to recolonisation. We took an adaptive approach to achieve large scale eradication of invasive American mink in a mainland area in North East Scotland where this species has devastating impacts on native biodiversity. Capitalising on the convergent interests of a diverse range of local stakeholders, we created a coordinated coalition of trained volunteers to detect and trap established and recolonising mink. Volunteers adopted rafts, floating platforms with a footprint-recording plate made of moist clay and sand under a wooden tunnel. Mink rafts are designed to act both as a monitoring device and as a trapping site for American mink. Raft monitoring also provides feedback on the impact of trapping, which helps to motivate project partners.

Starting in montane headwaters, we systematically moved down river catchments, deploying mink rafts, an effective detection and trapping platform. Within 3 years, most breeding mink had been removed from 10,570km2. The project expanded further and aims to cover 20,000 kim2 by end of 2013. The partnership is now led by Scotland's Federation of Rivers and Fisheries trusts, a natural economic stakeholder with increasing interest for biosecurity issues.

Throughout the project, we took an adaptive approach and explored both ecological and sociological components of the project by considering both mink and volunteer demography. Volunteers took increasing responsibility for raft monitoring and mink trapping as the project progressed and monitor > 85% of all rafts and account for most mink captures. The overall probability that a volunteer remained actively involved in the project was analysed as a survival process and varied according to profession. Fisheries staff had the highest retention, game keepers had the lowest and the retention rates of wildlife conservation professionals, local residents and land managers varied over time with evidence of gradual improvement.

In order to understand spatial heterogeneity in mink productivity and overcoming compensation through dispersal from adjacent uncontrolled areas we use genetic, age and reproductive data to construct pedigree relationships between American mink removed. These data are used to demonstrate: 1) large scale connectedness through dispersal between geographically distinct management units (river catchments); 2) differential rates of reinvasion in areas with different histories of control; 3) 'hotspots' that contribute disproportionately to spatial dynamics and represent significant management targets; 4) that relative increases in immigration following control are not sufficient to overcome reductions in density through culling. These findings have been used to define the appropriate spatial scale of control; allocate resources required to achieve specific goals for the conservation of native biodiversity; and have been instrumental in expanding the range of the mink-free area in Scotland.

Followed by lunch at the Grandstand. Please RSVP to Peter Banks

Time: 1-2pm

Location: DT Anderson Lecture Theatre (A08)

Contact: Peter Banks

Email: 0001261746781750565340723a0d335c371a4a15300f6a2b37