American Mink (Neovison vison)
The American mink is one of the larger members of the mustelid family, which includes animals like stoats, weasels and martens.
They have long slender bodies, ideal for entering the burrows of prey, and their streamlined shape helps them when they are swimming. They are between 30 to 45cm in body length, plus a 15 to 25cm long tail. Females are slightly smaller and lighter than males, weighing 400 to 800g as compared to a male’s body weight of 500 to 1500g. Weight also varies with season, with minks being heaviest in the autumn, as they put on weight in preparation for winter.
They have very soft and dense fur, usually dark brown or black in colour, often with white patches on the chest and belly. They have thick under-fur and oily guard hairs for good water-resistance, and webbed toes, all of which make them well adapted to a semi-aquatic lifestyle.
American mink are usually nocturnal.
Habitat and Distribution
The American mink’s native range is North America, covering nearly all of Canada and the US (except for the very dry parts of the southwest).
They are invasive in mainland Europe and the British Isles. Originally imported in the 1920s for fur-farming, escapees have since established several self-sustaining populations. Originally from escapes in the Iberian Peninsula, Scandinavia and Great Britain, they have now spread throughout Europe. The same thing has also happened in Russia, Iceland, China, Japan, and South America.
They are usually associated with aquatic habitats, and found near water sources such as streams, rivers, lakes, marshes, swamps, and occasionally coastline. They prefer dense vegetation.
They will sometimes dig their own burrows, or make dens out of tree roots, leaves, stones and branches, but it is more common for them to use the abandoned burrows of other mammals, including muskrat and beavers.
American mink are carnivorous. They eat a variety of prey, including small mammals, fish, amphibians, small birds, crustaceans, and invertebrates. They are opportunistic hunters, meaning they will usually eat whatever they can find – occasionally this can mean carrion. They tend to hunt on land and are not strong enough swimmers to pursue prey in open water.
Reproduction and Life Cycle
American mink are usually solitary animals.
Mating occurs between February and April, with births taking place between April and June. Females show delayed implantation (meaning fertilised eggs do not implant in the uterus straight away), so even though embryo development only actually takes 30 to 32 days, the total gestation period can take as long as 78 days.
Females will have a single litter of 2 to 10 young each year. The cubs or kittens are blind and have no fur when they are born. They open their eyes at 4 to 5 weeks old and are fully weaned at 5 to 6 weeks. They start hunting at 8 weeks but remain with their mums for another few months until the autumn.
American mink live for 3 to 4 years in the wild, and up to 8 to 10 years in captivity.
Conservation Status, Threats and Actions
IUCN Conservation Status: Least Concern
Population Trend: Stable
American mink are currently classified as Least Concern on the IUCN Red List.
They are not currently considered to be under threat, as they have a large, stable population. It’s possible that they may be affected by alteration or loss of wetland habitats and water pollution in their native range. Some hunting still occurs for their fur, but most mink fur is now produced on farms.
Mink can have serious impacts on native wildlife in areas where they are invasive. They have been implicated in the dramatic decline of water vole and ground-nesting bird populations in the UK. They also compete with otters and European mink, which they are slightly larger than.
There are no specific conservation measures in place. In fact, control measures are in place in areas where American mink are invasive. These include attempts at total eradication, helping populations of competitors (e.g. otters and European mink), and preventing further escapes from captive populations. It is now an offence to release a mink or to allow mink to escape.
- American mink can dive down as deep as 5 to 6m
- They will kill more prey than they can eat and store the leftover food for later on
- They have scent glands which they usually use to mark their territory, but they can also use as a defence mechanism when threatened
Our American Mink, full name Jessie Minkman, was born on the 4th of October 2013. He arrived at Five Sisters Zoo in May 2016.
To try and promote natural foraging behaviours keepers will often hide his food in tunnels, cardboard boxes, or containers suspended off the ground. Jessie enjoys searching for his food and storing some of it for later, like he would do in the wild.