#1 Amazon Weasel (Neogale africana)

The Amazon weasel, also known as the tropical weasel, is a species only found in South America. Early scientific records inaccurately described their native range as Africa, which led to their misleading specific epithet (the second part of their scientific name).⁽¹⁾

Appearance

Their fur varies from reddish to dark brown on the dorsal surface, and is pale orange-tan on the underparts. A stripe of the same colour as that on the dorsal surface runs down the centre of the neck and chest,⁽¹⁾⁽²⁾ a similar feature to that of the Colombian weasel.

Habitat

Although the full extent of their range is unknown, the Amazon weasel is found in humid areas, mainly in forests near the banks of rivers in the Amazon basin.⁽¹⁾ The Amazon weasel has naked foot soles and extensive interdigital webbing,⁽³⁾⁽⁴⁾ similar to the North American mink and Colombian weasel. This hints they are suited for semiaquatic life.

Behaviour

Little is published about the Amazon weasel’s behaviour in the open literature. The following are a list of sightings and specimen capture reported in Ramírez-Chavez et al.⁽⁴⁾ which give a glimpse into their behaviour. A live specimen was collected swimming in an estuary, nearly one half mile from the nearest shore. An Amazon weasel was trapped in a cage baited with corn and banana near a house on a rubber plantation. More specimens have been found burrowing in a hollow tree stump. Finally, while the exact species was not confirmed, four weasels reported to be Amazon weasels were sighted foraging together in the lower canopy of forest along the Rio Madeira in the Amazon.

Reproduction

There is little information in the open literature on the reproduction of the Amazon weasel. Comparisons of anatomy of the Colombian and Amazon weasel to the long-tailed weasel in South America in one study was not able to cover reproductive anatomy due to lack of specimens.⁽³⁾ It is presumed reproductive behaviour is similar to the Colombian weasel, North American mink, and long-tailed weasel, that comprise of a clade that radiated exclusively in the Americas.⁽⁵⁾

Diet

Little is known about the diet of the Amazon weasels, but they likely consume rodents and other small mammals.⁽¹⁾ Their dentition is specialised for a carnivorous diet.⁽⁴⁾ Interestingly, a specimen was captured using banana and corn as bait,⁽⁴⁾ but it may be speculated that another property of the bait or curiosity led the specimen into the trap.

Predators

As with most small carnivores and others in Mustela, the Colombian weasel is not impervious to predation by larger carnivores present in the Amazon rain forest. The Amazon weasel is of least concern conservation status, due to their large habitat range covering much of the Amazon rain forest.

Body length: 27–29.7 cm / 10.7–11.7 in
Tail length: 16–21 cm / 6.3–8.3 in
Weight: 700 g / 24.7 oz
Lifespan: Unknown (wild), unknown (captivity)
Range: Brazil, Ecuador, Peru and northern Bolivia.
Conservation status: Least concern
Subfamily: Mustelinae
Recognised subspecies⁽⁶⁾

References

#2 Colombian Weasel (Neogale felipei)

The Colombian weasel, also known as the Don Felipe’s weasel, is a rare weasel native to northern Ecuador and far eastern Colombia. Both their scientific and alternative common name honours the mammalogist Philip “Don Felipe” Hershkovitz.⁽¹⁾

The Colombian weasel is among the least known carnivores in the Americas, with only six confirmed records as of 2009. There is little quantitative information available about the species; most that is known is based on inference from anecdotal evidence through the few available collection records.⁽²⁾

Appearance

The dorsal surface and tail are blackish-brown, while the underparts are orange-buff. There is also a distinguish ventral spot on the neck that is the same colour as the dorsum, a similar feature to that of the Amazon weasel. Colombian weasels are observed to have webbed paws, which suggests they are perhaps semi-aquatic.⁽³⁾

Habitat

There is evidence that the Colombian weasel may have a water-rich habitat – the Colombian weasel has both naked foot soles and extensive interdigital webbing, hinting that they are suited for life near water.⁽⁴⁾ However, more quantitative data is needed to determine this claim with certainty.⁽²⁾

Behaviour

The Colombian weasel is rarely observed alive by humans (the first photograph of a live Colombian weasel was in 2011). Like other weasels, they are likely to be mainly solitary and sedentary.

Reproduction

Little is known about the reproduction of the Colombian weasel. Until further information is acquired, inferences based on other species are all that can be made. It has been noted that the baculum of a specimen of the Colombian weasel markedly differs from others in the Mustela family, terminating in three processes (“tips”) compared to other species, which have a single termination.⁽⁴⁾

Diet

Little is known about the diet of the Colombian weasel, but due to their webbed paws and occurrence in riparian habitats, they are assumed to eat fish and other aquatic organisms, in addition to terrestrial small mammals, birds and insects.⁽³⁾

Predators

As with most small carnivores and others in Mustela, the Colombian weasel is not impervious to predation by larger carnivores. Hunting by humans is expected to be a threat to Mustela Felipei, despite their conservation status in Ecuador and Colombia preventing their killing. Active culling of long-tailed weasels in the area by the local populace to mitigate predation by small domestic livestock may presumably also affect local Colombian weasel population. Additionally, they may be hunted along with the long-tailed weasel for traditional medicinal purposes.⁽²⁾

Body length: 22 cm / 8.7 in
Tail length: 11.5 cm / 4.5 in
Weight: 120–150 g / 4.23–5.29 oz
Lifespan: Unknown (wild), unknown (captivity)
Range: Western Colombia to northern Ecuador.
Conservation status: Vulnerable
Subfamily: Mustelinae
References

#3 Long-Tailed Weasel (Neogale frenata)

The long-tailed weasel, also known as the bridled weasel, is distributed from southern Canada throughout much of the United States and Mexico, southward through all of Central America and into portions northern South America.

Appearance

Several species bear some resemblance to another, and the long-tailed weasel has a few look-alike cousins in the North American stoat, Haida stoat, and Eurasian stoat. All of these species have a black tail brush that serves the same function, all (depending on the subspecies) are capable of turning white for winter in the North, and all overlap in size. By closer inspection, the characteristics are different in several aspects: Like the name suggests, the tail is notably longer, the ears are taller and the skull is less streamlined with a wider muzzle. When not in their white winter coat, the long-tail’s colours and contrasting facial markings sported by some of the subspecies in dark brown and white can easily help as an identification factor.

Overall they are a warm shade of sandy-brown on top, yellow to orange-buff below and sports white paws, but due to their wide distribution, the markings and colour depth have an impressive variation. Some do not have facial markings at all, and the so-called bridled weasel (subspecies: N. f. xanthogenys) from California is perhaps the most recognisable of them all, having been nicknamed for their bridle-like mask. The intensity of the pigmentation is caused by the level of humidity in an area, a phenomenon called Gloger’s rule.⁽¹⁾

Winter coat

Their winter coat is the same as the least weasel, North American stoat, Haida stoat, and Eurasian stoat—slightly longer, very dense and white. Only certain subspecies native to colder climates undergo the moult cycle. The tip of the tail always remains black. Unlike the stoats, the long-tailed weasel is not typically called an ermine while in their winter coat.

Habitat

The long-tailed weasel prefers habitats with ample levels of cover with access to prey. Reed grass, shrub, and brushlands are desirable for their cover.⁽²⁾

Behaviour

The majority of the weasels are strictly solitary and polygamous, with the female having the responsibility for raising the young, while the males travel long distances to mate with as many females as possible. The long-tailed weasel is not an exception to the rule, but the male has been known to show a little more hospitality than just leaving the family to themselves after he has done his work. Like the Eurasian stoat, the male long-tail will occasionally bring “gifts” in the form of caught prey to the den, most likely in attempt to calm the defensive aggression of the nesting female and thus gain access to mate with her. The difference is that the male long-tail weasel does this more frequently, and because the females have to do some growing before they are sexually mature, investing in providing for them may help their survival and increase the numbers of potential mates.⁽³⁾

Reproduction

The times and duration for which the long-tailed weasel is in season is dependent on geography. One study,⁽⁴⁾ noted that in northern Kentucky, female long-tailed weasels (subspecies: N. f. noveboracensis) become in season within the range of 30th March to 16th June, and are out of season within the range of 21st July to 17th September. This is contrasted with long-tailed weasels in Montana (subspecies: N. f. oribasus), whose oestrus season was half as long. Males have similar periods of spermatogenesis.

Diet

Long-tailed weasels are generalist predators eat a wide variety of prey, including rodents, lagomorphs, birds, and bird eggs.⁽²⁾

Predators

Larger predators may all see the long-tailed weasel as a target. For example, in southern California, coyotes and bobcats⁽⁵⁾ have been identified to prey on long-tailed weasels, and in Pennsylvania, foxes and raptors are known predators. The North American marten has been reported to sometimes prey on the long-tailed weasel.⁽⁶⁾

Possible declining numbers

While there is currently no widespread conservation effort for the long-tailed weasel in North America, a recent study has found that their numbers appear to be declining at a concerning rate in many parts of the continent.⁽⁷⁾

Body length: 33–42 cm / 13–16.5 in (males), 28–35.5 cm / 11–14 in (females)
Tail length: 13.2–29.4 cm / 5–11.5 in (males), 11.2–24.5 cm / 4.5–9.5 in (females)
Weight: 226–401 g / 8–14.6 oz (males), 130–178 g / 4.5–6 oz (females)
Lifespan: Unknown (wild), up to 9 years (captivity)
Range: Southern Canada, all of the United States and Mexico, Central America and northern South America.
Conservation status: Least concern
Subfamily: Mustelinae
Recognised subspecies⁽⁸⁾

References

#4 North American Mink (Neogale vison)

The North American mink, also more commonly known as the American mink, or simply mink, is native and widespread throughout the United States and Canada, but can also be found introduced in Eurasia and southern South America. Both “minks” and “mink” are used as plural forms of the species.

The North American mink is often superficially compared with the European mink, but they are not directly related. The European mink is much closer related to the European polecat and Siberian weasel.⁽¹⁾⁽²⁾ In 2021, the North American mink was reclassified from the genus Neovison⁽³⁾ to Neogale.⁽⁴⁾

Domestic or feral versus native wild minks

Domestic or feral North American minks (also known as ranch or farmed) are not the same as native wild North American minks. For over 150 years humans have intentionally bred these minks to be larger, less temperamental, have thicker pelts, and various pelt colours.⁽⁵⁾ Therefor, both domestic and feral North American minks (Neogale vison domesticus) are phenotypically and genetically different from their wild counterparts. This is why despite the fact that they are often not considered a pet like a ferret, they are still domesticated animals by definition.⁽⁶⁾ We will primarily be discussing details about the wild North American mink.

Appearance

Relatively slim, but the face in particular has blunt and boxy features. The eyes are small and the nose is large in comparison, emphasised by prominent whisker pads that gives the mink an otter-like quality. The long and dense fur hides most the ears and emphasises the robust anatomy. Their paws are partially webbed and more sparsely furred than the rest of the body—supporting their semi-aquatic nature. The fur is chocolate to reddish brown in colour, and usually decorated with white patches on the chin, chest, or throat. It is smooth and thick in structure, with oily guard hairs that waterproof the coat.

Winter coat

The winter coat tends to be longer, denser, silkier, and darker than the summer coat. The coat does not turn white for winter.

Habitat

They dwell in forested areas near rivers, streams, lakes, ponds, and marshes, often with some sort of bushy or rocky cover nearby.⁽⁷⁾

Behaviour

North American minks are mostly nocturnal and solitary animals, with males being particularly intolerant of one another. There is however, extensive overlap in territories between the opposite sex. Their home ranges are usually 1–6 kilometres (0.62–3.73 miles) long, with male territories larger than females’.⁽⁸⁾ Like most mustelids, they use their enlarged anal glands to mark the boundaries of their territories.

They will dig their burrows in river banks, lakes, and streams, as well as holes under logs, tree stumps, or in roots and hollow trees. They will at times use abandoned dens of other mammals, such as badgers, skunk,s and muskrats. Sometimes dens located in rock crevices, drains, and nooks under stone piles and bridges are also chosen. The burrows that they dig themselves are usually four inches in diameter, and may continue along for 300–370 cm (10–12 feet) at a depth of 61–91 cm (2–3 feet).⁽⁹⁾ These burrows are characterised by numerous entrances and twisting passages, consisting of one to eight exits.⁽¹⁰⁾ They will occasionally line the interior of their den with dried grass and leaves, or fur from past prey.⁽⁷⁾ North American minks are also excellent swimmers, and have been reported to swim 30 metres (100 feet) underwater, and dive to depths of 5 metres (16 feet).⁽¹¹⁾

Reproduction

Mating season ranges from February in the southern range, and to April in the north, and lasts for three weeks. The mating process is aggressive, with males typically biting the nape of the female’s neck and pinning her with his forepaws. Mating can last anywhere from 10 minutes to four hours. Once a female is impregnated, the gestation period last from 40 to 75 days. The young are born from April to June, with litters consisting of four kits on average. The kits are blind at birth. They depend on their mother’s milk for five weeks, and begin hunting after eight weeks of age. They do not become fully independent until autumn. Sexual maturity is reached the following spring at about 10 months old.⁽¹²⁾

Diet

Their diet varies by season and region. During the summer they consume crayfish and small frogs, as well as smaller mammals such as shrews, rabbits, mice, and muskrats. Fish, ducks and other water fowl provide additional food choices.⁽⁷⁾ In British Isles, European rabbits are common summer prey, while European hares are preyed on occasionally.⁽¹³⁾ In South America’s Cape Horn Biosphere Reserve, several native and exotic mammals are their main prey.⁽¹⁴⁾

Surplus killing

They will occasionally exhibit surplus killing behaviour when presented with an abundance of food. However, surplus food is often carried to a den to be cached for later consumption.⁽¹⁵⁾ This is more beneficial during the winter months when carcasses do not spoil as quickly. It is possible that surplus killing in North American minks is an evolutionary response to unpredictable food resources.⁽¹⁶⁾

Predators

Although adult North American minks can generally defend themselves, their young can fall prey to bobcats, coyotes, wolves, and birds of prey.⁽⁷⁾

Introduced range and fur farming

Their fur has been highly valued for use in clothing, with hunting giving way to fur-farming. Their treatment on fur farms has been a focus of animal rights and animal welfare activism.⁽¹⁷⁾ According to the Game & Wildlife Conservation Trust, there is a modern misconception that Britain’s feral North American minks originated from mass releases by wildlife activists in the 1990s, when in actuality the wild population was established decades earlier.⁽¹⁸⁾

Between the 1920s and 1950s, North American minks were imported from North America to Europe, the USSR, and southern South America to stock fur farms. In parts of Europe, escaped and released farmed North American minks have established self-sufficient feral populations, and have been classified as an invasive species linked to the decline of the European mink,^(19)(20) as well as other small mammals and birds. Pejorative humanisations of the North American mink by the public remain chronic. Nevertheless, we cannot shift full blame on to them for this ecological disruption, since they were wilfully introduced to the continent, despite the reasonably foreseeable consequences from possible escapes or releases.

The North American mink was also once the scapegoat for the decline of the Eurasian otter population in Great Britain.⁽²¹⁾ Further studies revealed that during the mid-20th century many otters were dying from dieldrin poisoning—an organochlorine insecticide used by farmers.⁽²²⁾ Dieldrin was withdrawn from use in 1962 and eventually banned in 1989.⁽²³⁾

Colour mutations

Selective breeding of farmed North American minks (also referred to as domestic mink) have resulted in a range of colours from beiges, greys (silverblue), speckled black and white (jaguar), and to a brown that is almost black.⁽²⁴⁾ Minks are often portrayed as pure white in cartoons and other visual media, but this colour too (unless born albino) is usually only seen in farmed mink. Their natural fur colour is brown.

Possible decline of wild minks in North America

Due to large numbers of farmed North American minks escaping or being recklessly released from fur farms, some wildlife biologists are concerned that the wild populations in North America are not only threatened by disease and competition for resources with these feral minks, but also by hybridising with them.⁽²⁵⁾

Both types of minks are solitary and territorial, and overpopulation often results in the animals killing each other through direct conflict, or by causing weaker minks to be driven from their territory until starvation sets in. Too many farmed minks escaping or being released into the wild and becoming feral can flood the ecosystem and cause disruption—resulting in not only the deaths of the majority of the feral minks, but as well as many of their wild counterparts from starvation or injuries incurred while fighting over territory.⁽²⁶⁾ If a farmed mink manages to survive long enough to reproduce, it may lead to weaker genes being added to wild populations, which can also contribute to their decline.⁽²⁵⁾ This is believed to be a contributing factor for the decline of wild North American minks in parts of Canada.⁽²⁷⁾

SARS-CoV-2 outbreaks on mink farms

North American minks are susceptible to SARS-CoV-2 (the virus that causes COVID-19) infection, and there have been numerous outbreaks reported on mink farms in Europe and North America. [Further reading on this subject…]

Use in hunting (minkenry)

North American minks can make good hunting companions if properly trained during their youth, as demonstrated by Joseph Carter “The Mink Man” on his YouTube channel.

Body length: 34–45 cm / 13–18 in (males), 31–37.5 cm / 12–15 in (females)
Tail length: 15.6–24.7 cm / 6–10 in (males), 14.8–21.5 cm / 6–8 in (females)
Weight in winter: 500–1,580 g / 1–3 lb (males), 400–780 g / 1–2 lb (females)
Lifespan: Up to 10 years (wild), up to 11 years (captivity)
Range: North America, and introduced to parts of Eurasia and South America.
Conservation status: Least concern
Subfamily: Mustelinae
Recognised subspecies⁽²⁸⁾

References

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Old World Weasels | New World Weasels | Polecats | Ferret

What Are Mustelids?

Badgers | Ferret-Badgers | Fisher | Grisons | Martens | Otters | Tayra | Weasels | Wolverine