African striped weasel

The African striped weasel (Poecilogale albinucha), also known as the white-naped weasel, striped weasel or African weasel, is a small mammal native to sub-Saharan Africa, where it occurs as far north as Kenya and stretches down south to South Africa. It belongs in the family Mustelidae and is the lone member of the genus Poecilogale, which was established in 1883 by Oldfield Thomas. It has a long, slender body with short legs and a bushy tail. One of the smallest carnivorans in Africa, it measures 24 to 35 cm (9.4 to 13.8 in) long excluding the tail, with males generally growing larger than females. It has black fur over most of its body, with distinctive white bands running from the top of its head down the length of its back, and the tail is completely white.
Often associated with termite mounds, the African striped weasel is most commonly seen in savanna and veld grasslands, but has been recorded in a wide range of habitats including semideserts, rainforests, fynbos and even areas with human development such as pine plantations and agricultural land. It is a powerful digger and excavates burrows which it inhabits when not hunting for prey. Though not commonly seen due to its secretive nature, it has been listed as Least Concern on the IUCN Red List since 1996 because of its wide range and habitat tolerance. No major threats are known to this weasel, though it is very commonly used in local traditional medicine. Owls and dogs may prey on it, and weasels sometimes die in fights against others of their own kind. It generally flees from any perceived threats, but if this is not possible, it may try warding off its attacker with noises, fake charges or a noxious fluid sprayed from its perineal glands.
This animal is a specialized predator that feeds almost entirely on rodents, and will enter their burrows to catch them, though it occasionally eats birds as well. Even when hungry, it ignores other types of small animals and eggs provided to it as food. It commonly bites its prey in the back of the neck while rolling around or kicking the prey's back in a likely attempt to dislocate the neck, though larger prey may instead be dispatched with bites to the throat. This weasel rarely drinks water, only doing so in small quantities when the weather is hot, instead obtaining most of the moisture it needs through its food. It is mostly a nocturnal and solitary animal, though small groups of up to four individuals are sometimes seen. Breeding takes place from spring to the end of summer, and females tend to give birth to two to three young per litter after a gestation period of about 30 days. The newborn young are pink and almost hairless, with closed eyes and ears, and are cared for by their mother with no assistance from their father.
The African striped weasel was first described in 1864, when British zoologist John Edward Gray studied a skin of this animal purchased by the British Museum ten years earlier and labeled as that of a zorilla. He recognized that this skin was unlike that of any other known mustelid, and determined that it represented a new species which he named Zorilla albinucha. The specific name combines the Latin words albi meaning 'white' and nucha meaning 'nape'. Five years later, Gray published a catalog of some of the mammal specimens in the British Museum, in which he moved the species into the genus Mustela as Mustela albinucha, commenting that it only has the coloration of a zorilla. In 1883, another British zoologist, Oldfield Thomas, noticed that the species had significant differences in the skull compared to any of the known mustelid genera, and established the new genus Poecilogale, with the only species Poecilogale albinucha. The generic name is derived from the Ancient Greek words poikilos (ποικίλος), meaning 'particolored' or 'cunning', and galē (γαλῆ), meaning 'weasel'. Thomas' study was based on five African striped weasel specimens, four of which were kept in the British Museum and the remaining one was in the Paris Museum of Natural History.
In 1865, German naturalist Wilhelm Peters reported a mustelid specimen from Golungo Alto, Angola under the name Zorilla africana. This was because Austrian explorer Friedrich Welwitsch told him that the specimen represents a form consistently different from the African striped weasel and that even the locals refer to them by different names. However, Peters himself thought it was simply a variant of the African striped weasel. In the same year, Portuguese zoologist José Vicente Barbosa du Bocage studied two skins and a skeleton of African striped weasels from Calandula, Angola and proposed that the animal's scientific name be changed to Zorilla flavistriata. Both Zorilla africana and Zorilla flavistriata are no longer deemed valid names, and are now considered junior synonyms of Poecilogale albinucha.
A number of African striped weasel subspecies have been proposed during the 20th century, though there is debate as to how many of these are valid. Some authors believe that the species is monotypic and that all proposed subspecies should be considered invalid. The following five subspecies were recognized in the third edition of Mammal Species of the World published in 2005:
The African striped weasel is the only species in the monotypic genus Poecilogale, which belongs in the subfamily Ictonychinae within the family Mustelidae. Members of Ictonychinae have been divided into two tribes, known as Ictonychini and Lyncodontini. This species is part of Ictonychini, which it shares with the striped polecat, Saharan striped polecat and marbled polecat. Results of genetic analyses indicate that the closest living relative of the African striped weasel is the striped polecat, with the two being recovered as sister taxa in multiple studies. A study published in 2008 suggested that the lineages of these two species diverged between 2.7 and 2.2 million years ago, while a 2012 study proposed an earlier date between 4.3 and 3.4 million years ago. The following cladogram shows the position of the African striped weasel among its closest living relatives according to Gray and colleagues (2022):
A fossil species, Propoecilogale bolti, was originally named as a member of the genus Ictonyx, but has been placed in a separate genus since 1987. This prehistoric animal shows features in its skull and teeth that are intermediate between Ictonyx and Poecilogale, and has been suggested to be an ancestor of the African striped weasel. The most complete fossil specimen of Propoecilogale was discovered in the Early Pliocene-aged deposits of Laetoli, Tanzania, and a geologically younger specimen is known from the Early Pleistocene-aged deposits of Cooper's Cave, South Africa. The Cooper's Cave specimen shows a larger first molar tooth with a more reduced metaconid compared to the Laetoli specimen. It has therefore been proposed to represent an intermediate stage between the Laetoli specimen and the modern African striped weasel in the evolution of the Propoecilogale-Poecilogale lineage.
One of the smallest carnivorans found in Africa (along with the dwarf mongoose), the African striped weasel has a slender body and short legs, and is the proportionally longest mammal native to the continent. Adults have a head-body length of 24 to 35 cm (9 to 14 in), with the tail adding a further 13.8 to 21.5 cm (5 to 8 in). This species exhibits sexual dimorphism in size, with males larger than females. Six males sampled in KwaZulu-Natal in 1978 weighed an average of 339 g (12 oz), and three sampled in the former Cape Province in 1981 had an average weight of 357 g (13 oz). In comparison, 251 g (9 oz) and 215 g (8 oz) were the average weights of females according to the same respective studies, with the former sampling six females and the latter sampling two. The fur is mostly black, with a white patch on the top of the head which divides into two and then four white to pale yellowish bands running down the back. The bands may change in hue and become darker, with those of one subadult recorded to change from white to a light honey colour in about six weeks, and those of another captive individual reported to change from light yellow to deep buff. Staining caused by the soil in the animal's habitat may cause these bands to appear red, grey or yellow, particularly in periods of rain. The width of the bands varies between individuals; some specimens found in Botswana have bands reaching 1.5 cm (0.6 in) in width, whereas they only reach 0.7 cm (0.3 in) in others. The tail is completely white in colour and has a bushy appearance, with each of its hairs growing about 3 cm (1 in). In comparison, most of the body has hairs which are around 1 cm (0.4 in) long, and those on the limbs are only 0.5 cm (0.2 in) long.
The head is elongated, with the skulls of some females measured in 1951 reaching an average length of 5.13 cm (2 in) and an average width of 2.36 cm (1 in) at the zygomatic arches (cheek area). The lower jaw fits tightly into the jaw joint, which greatly limits the weasel's ability to move its jaw from side to side. The carnassial teeth are sharp, and the canine teeth long. The dentition has a dental formula of 3.1.2.13.1.2.1, that is, three incisors, one canine, two premolars and one molar on either half of each jaw, for a total of 28 teeth. This differs from the closely related striped polecat in having one less premolar on each side of each jaw and one less molar on each side of the lower jaw. The absence of those teeth is a derived trait differing from the ancestral condition retained by the striped polecat, as are some features of the cusps of the first molar (namely the absence of a metaconid and the fusion of the metacone and paracone). This animal has small eyes, a short, broad snout, and short, rounded ears.
As in other mustelids, the limbs of an African striped weasel each have five digits, and each digit bears a claw. The front claws are larger and more curved than the hind claws. The undersides of the paws are mostly hairless, each one having a large, four-lobed pad, with each front limb having two additional carpal pads on the wrist. In this aspect it differs from some mustelids (whose paws have hairy undersides) and is most similar to the Malayan weasel and back-striped weasel. However, the African striped weasel differs from these two species in having larger front claws and the third and fourth digits of the hind limbs being closer together. This makes it a rare example of a mustelid whose paws are intermediate in form between cursorial paw forms (like in the Malayan and back striped weasels) and fossorial paw forms (like in the striped polecat). The claws are sharp and curved. Females typically have four teats, though some have been found with six. Like many other mustelids, the African striped weasel has a pair of well-developed scent glands in the perineal region that can spray a noxious fluid when the animal feels threatened.
African striped weasels inhabit much of Africa south of the equator. They are found from the Democratic Republic of the Congo to Kenya in the north, and as far south as southern South Africa. Within this region, they occur in moist habitats with an annual rainfall of over 60 cm (24 in). They are often associated with termite mounds in savannah and veld environments, with a 1978 survey revealing that 75% of African striped weasel sightings were made in such grasslands. However, the species appears to tolerate a wide range of habitats, having also been seen in semideserts, rainforests, fynbos and pine plantations, and roadkill carcasses have been collected in agricultural land. Considering the increase in sightings from regions formerly believed to be unsuitable for them, the weasels may be overlooked across much of their range due to their secretive nature. They commonly live below 1,500 m (4,921 ft) elevation, but may occasionally be found as high as 2,200 m (7,218 ft).
African striped weasels are mostly nocturnal and generally solitary, but may occasionally be seen in pairs or family groups of up to four individuals. Males are aggressive when they encounter one another, at first fluffing their tails, making short cries and fake charges, and then escalating to fighting with bites, shaking, and aggressive shrieks if neither individual retreats. This species walks with a distinctive gait, with the body extended or arched while the nose is held low to the ground, swinging the front part of its body from side to side in a snake-like manner. It regularly stops to stand on its hind legs so that it can survey its surroundings. These weasels are effective diggers and construct their own burrows, sometimes teaming up in pairs to do so, using their front limbs to dig into the ground and their hind limbs to kick soil backwards. However, they may sometimes rest in natural cavities such as hollow logs or rock crevices. They defecate in well-defined latrine locations, raising their tails almost vertically when doing so, possibly as a means of scent marking. In the wild, these latrines are commonly at the bases of trees and termite mounds, whereas captive animals may deposit dung against a vertical wall instead.
African striped weasels have been identified as making six different calls. Apart from the warning and aggressive calls mentioned above, and a third call that transitions between the two, another call signals submission of a retreating male. In addition, there is a call which indicates surrender during a fight, and a greeting call is used only between males and females and between young and their mother. Young weasels also make distress calls when separated from their mother. Captive females with nursing young have been recorded to dip their necks into water during very hot weather, which may be to both cool themselves and carry water so that they can moisten and cool their young.
African striped weasels are specialist predators known to hunt small mammals and birds, with the vast majority of their diet consisting of rodents of their own size or smaller, and will travel into the burrows of rodents to hunt them. They do not feed on invertebrates, reptiles, amphibians or bird eggs, and experiments conducted in 1978 showed that even hungry individuals offered these items as food will ignore them. The weasels hunt primarily by scent, attacking prey with a sudden lunge and striking at the back of the neck. After the initial strike, they roll around and kick the prey animal's back, possibly to dislocate the prey item's neck. When taking on larger prey such as rats, which can weigh more than the weasels themselves, adult female weasels bite at the throat instead, though males have not been recorded doing this. Prey is generally eaten whole while the weasel is in a crouched pose, though the feathers and legs of birds and the stomachs of mammals are sometimes left uneaten, and the weasel will not use its front limbs to stabilize its food. Although African striped weasels eat smaller prey weighing up to 180 g (6.3 oz) head first, larger prey is eaten from the shoulder first. They sometimes store prey in their burrow instead of eating it immediately, picking up small prey by the back skin off the ground and dragging larger prey backwards towards the storage area. The gut of an African striped weasel is between 1.75 and 2 times the length of its body excluding the tail, and food passes through rather quickly, with defecation occurring approximately 165 minutes after the food was consumed.
These weasels do not drink frequently, apparently gaining most of their moisture requirements through their food. When they do drink, they do so by lapping up water with their tongues. A male kept in a cage for two weeks during the winter did not drink at all during this time, and only occasionally drank small amounts of water during hot weather.
The breeding season of the African striped weasel is extensive, lasting from spring to the end of summer. The testes of the male remain large from September to April (spring to early autumn) and are shrunken for the rest of the year. The male makes a quiet chattering sound, believed to be a greeting call, when courting a female during this time. If the female is receptive, she may indicate so by dancing around the male and allowing him to grasp her neck from behind, smell her vulva and nibble on her cheek. During mating, the male continues to grasp the back of the female's neck while clasping his forelimbs around her pelvic region. The duration of copulation is variable and can be as short as 27 minutes, though it typically lasts between 60 and 80 minutes. At least three bouts of copulation can occur within a single 24-hour period. Females give birth to one litter per year of two or three young after a gestation period of about 30 days, though they may have a second litter if the first is lost early, and rear the young with no assistance from the males.
Birth takes place in a burrow during the daytime, and the mother eats the placenta afterwards. The newborn young weigh just 4 g (0 oz) each. They are almost hairless, with their pink skin visible over most of the body, a mane of white hair on the back of the head, and a hump extending from the back of the head to the shoulders. Their mother carries them by this hump until it and the mane disappear at seven weeks, at which point she carries them by the scruff of the neck instead. Newborns have closed eyes and ears, making them blind and deaf, despite the eye slits and pinnae already being present. Dark skin pigment is developed at an age of seven days, and the distinct black and white coloration of the species becomes visible when the young reach 28 days of age. Their milk canine teeth erupt at five weeks, at which point they begin eating the soft parts of prey killed by their mother, with permanent canines erupting at 11 weeks before the milk canines are shed. Their eyes open between 51 and 54 days after birth. By 11 weeks of age, they are weaned, and they start killing their own prey at 13 weeks. They reach the full adult size at 20 weeks, and are sexually mature at eight months.
The lifespan of the African striped weasel is short, with captive individuals recorded to only live for five or six years. Tuberculosis of the spleen is a known cause of death in some captive weasels. Members of this species are also known to kill each other in intraspecific fights. Documented predators of wild individuals include owls and domestic dogs, and humans also sometimes trap and kill them when they visit chicken houses or to use them in traditional medicine. Vehicular collisions lead to some African striped weasel deaths, as evidenced by roadkill carcasses found in agricultural areas. The tapeworm Taenia brachyacantha is a confirmed parasite of this species.
When startled, African striped weasels attempt to flee by escaping into a hole, or (according to anecdotal evidence) occasionally by climbing up trees. If unable to flee, the animal may emit a sound similar to a growl or shriek while raising its tail and making fake charges at the perceived threat. If this does not ward off the threat, the weasel may spray a yellowish, musky fluid from its perineal glands, and the stream can be ejected up to 1 m (3 ft 3 in) away. Though this fluid has a heavy, sweet and pungent smell which has been described as "foul", it apparently is not nauseating and less persistent than the similar secretions of skunks and striped polecats.
The IUCN first assessed the African striped weasel in 1996 and listed it as Least Concern, with the same listing given in subsequent assessments in 2008 and 2015. It was assessed as such because although it is not commonly seen, it has a wide distribution and habitat tolerance. The IUCN did not make any population estimates for the species, simply stating that the number of mature individuals is unknown, but notes that it is "rare to uncommon" in its range. The species is believed not to face any major threats, even though it is one of the most regularly used species in local traditional medicine. In addition, its skin is used as a good luck charm. Modification of the weasel's preferred grassland habitat due to human activities such as agriculture and livestock grazing may also pose a threat to this animal. Across the former Cape Province of South Africa, the African striped weasel is a protected species, but elsewhere in the country it is only protected within nature reserves and national parks.