American mink first arrived in Britain in 1929, but only in commercial fur farms. They were first reported to be breeding wild in the UK in 1956, as a result of escapees and deliberate releases. Today it is virtually impossible to estimate the number of mink living in our waterways.
Mink numbers have increased rapidly in the last 30-40 years, and they are now common and widespread. They are semi-aquatic and are frequently encountered on our canals and river systems.
Close up, American mink resemble something between a small cat and a ferret. They have a dense coat of deep brown fur, which often leads to cases of misidentification with the native otter. However, otters are shy animals unlikely to be seen during the day - quite unlike their confident American cousins who will wander the waterways at all hours. Mink are also smaller and slimmer than otters, which makes it easier for them to hunt burrow-dwelling prey such as water voles.
These efficient predators are solitary animals that will fiercely defend their waterside territories. Males will sometimes allow females to make their homes inside their vast territories, but no male mink will tolerate another male nearby.
In the UK, the water vole has been in decline since the beginning of the twentieth century, due to habitat loss, degradation and fragmentation. However this decline accelerated sharply throughout the 1960s and 1970s, coinciding with the spread of American mink in the wild. Unless some areas are kept free or relatively free of mink, it is considered that the water vole will become extinct in much of Britain within a few years. The urgency of the situation is highlighted by the water vole's inclusion as a priority species in the UK Biodiversity Action Plan and the promotion of humane mink control as an essential tool in water vole conservation, within the National Species Action Plan (SAP, 1997).
The Canal & River Trust supports targeted control of American mink, in order to protect our waterways, as well as for the conservation of water vole populations. Mink control will protect our considerable investment, in recent years, in habitat improvement for water voles across the network.
Appearance: Feral mink are naturally a chocolate-brown colour but farm-bred animals can vary in colour from white or grey through to black. Limbs are short and tails are about one third of their body length
Lifespan: Up to 8 years. Few survive beyond their second year in the wild
Diet: Mink are opportunistic predators who will happily eat a variety of fish, small mammals, birds and invertebrates
Last date edited: 29 July 2015