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American mink

What action is going on for this species?

The following will give you information on what work has been taking place through the Species Action Framework :

Species background

The American mink (Neovison vison) is a semi-aquatic carnivore that first became established in the wild in Britain in the 1950s following numerous escapes and releases from fur farms. It has now spread throughout most of the country.

Why is this on the Species Action List?

The American mink meets criterion 2 of the Species Action Framework as an invasive nonnative species which presents a significant risk to biodiversity.

It is a generalist predator that can have a serious impact on a range of vulnerable native prey species.  The animal has been well studied and management options are available to deal with it at a local level.  Control of mink would benefit a range of species on which it predates, such as water voles and ground nesting birds (water vole is also on the Species Action List and actions relating to this species cross-link to mink).

The Wildlife and Countryside Act 1981, as amended, makes it an offence to release mink or allow them to escape into the wild.  The Mink Keeping (Scotland) Order 2003 prohibits the keeping of the species in Scotland except under licence.

Habitat, distribution and abundance

Mink are usually associated with aquatic habitats, including coastal areas where the species can be particularly abundant. Following several introductions in the UK they have spread throughout the mainland except to, as yet, Caithness and most of Sutherland. They are present on the Western Isles (Harris and Lewis) and some other Hebridean islands. The Scottish population was estimated at 52,250 (+/- 50%) in a 1995 study (110,000 for the UK as a whole), although a more recent estimate suggests a figure of 19,450 based on 1996-98 data.

In Europe, American mink are now present over much of northern Europe including Iceland, but also in isolated areas further south and west.

General ecology

Mink are extremely adaptable opportunist predators and can exploit a wide range of mammals, birds and fish.  The sexes live apart and occupy individual linear territories, typically 1.5-2km in length.  In freshwaters, watercourses with plenty of bank-side tree cover are preferred.  In coastal areas they prefer more sheltered sites with large rock pools.

History of invasion and expansion

The first feral populations of mink were recorded in the 1950s in England.  Colonization by mink in Scotland has taken longer and has occurred in the context of an increasing otter population.  Three national otter surveys undertaken from the late 1970s to early 1990s, and subsequent records, indicate an overall increase in mink, although anecdotal evidence suggests that mink may be declining in some parts of Scotland.

Impacts on other biodiversity and conservation interests

As mink are generalist predators they can affect prey species which do not form an essential part of their diet, while remaining unaffected by a decline of the prey population as they can switch back to alternative prey.  There is strong correlative evidence that mink are implicated in the drastic decline of water voles in the UK.  Mink are also known to predate a range of bird species.

Other species, not closely associated with water, are also vulnerable to mink predation and have potentially reduced in numbers as a consequence. 

The effect of mink predation at seabird colonies on the west coast of Scotland has been the subject of long term studies. Between 1989 and 1995 mink caused widespread, whole-colony breeding failures and declines in breeding numbers of black-headed gulls, common gulls and common terns, as a result of predation on eggs and chicks.  Colonies on or near the mainland were most affected. 

Mink may also account for a large proportion of salmonid mortality in some river systems.

The 'Species Lead' at Scottish Natural Heritage

Robert.Raynor@snh.gov.uk   Tel 01463 725000