Sophisticated mink control

Key achievements

• The GWCT Mink Raft was used to steer incisive mink control on two rivers in southern England.
• Water vole numbers built up substantially during the absence of mink. 
• Water voles recolonised stretches from which they had been absent while mink were present.
• GWCT Mink Raft wins award from animal welfare organisation.
• The invention of the GWCT Mink Raft in 2002 initiated two years of intensive research on how best to manage the introduced mink for the benefit of native wildlife such as water voles.

The mink control projects on the River Itchen in Hampshire and the River Wylye in Wiltshire, already reported in the Trust's Review of 2003, continued in 2004. On the Wylye, Trust research staff, Mike Short and Tom Porteus, have maintained both monitoring and trapping roles. On the Itchen we reduced our involvement to a monitoring role only, in line with available funding, relying on the river keepers to provide the low level of trapping required.

In both cases, mink presence was held at near-zero levels from the start of the project to the end of July 2004, allowing water vole numbers to build rapidly from initial levels (see Figure 1). Indeed, water voles have been so numerous on the Wylye that they actually hindered the discovery and trapping of mink that appeared there in late summer. The latter appeared to be a female with young which either moved in from adjacent rivers, or perhaps were missed somewhere along the river corridor.

Overall, though, we were very satisfied that the GWCT Mink Raft   had proved itself in practical mink control, and that we had developed a near-optimal strategy for using it in these conditions.

Figure 1. Mink and water vole activity on the River Itchen, April 2003 to October 2004

	Mink captures
	Mink activity
	Water vole activity

There are several aspects of mink control that we would like to improve further, but shortage of external funding prevents us undertaking the research. Our involvement on the Wylye has now ended due to lack of funding, though the Itchen project is still being funded at a modest level by the Environment Agency, which also funds mink removal projects elsewhere in the UK.

In general, there is a clear shortage of money in the UK for water vole conservation, and it is understandable that - having been given a viable technique for mink control in the form of the GCT Mink Raft - conservation agencies and Wildlife Trusts now place the emphasis on action rather than further research. At a national level, policy for water vole conservation is led by the Environment Agency, whereas Defra has the lead role in devising policy for introduced and invasive species such as the mink.

Unusually, mink control is a case where predator control is wanted outside the game management sector. It has allowed us to discuss predator control issues with audiences for whom predator control is normally a distasteful and taboo subject, and to demonstrate that a rational and sensitive approach is possible.

The GWCT Mink Raft continued to attract considerable attention in 2004, and has been adopted by conservation bodies all over the country. In September, further press coverage was prompted by our receipt of the 2004 Wild Animal Welfare Award (the first ever offered) from the Universities Federation for Animal Welfare (UFAW). This award recognised that, by ensuring focused, effective trapping, mink rafts also deliver benefits in welfare, for both target and non-target animals. UFAW is very much a science-driven organisation, hence we were delighted to receive this acknowledgement from them of the improvements we had made to mink control practice. The award was presented by Minister Ben Bradshaw, which in itself ensured awareness of the issues at the highest levels.