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 its range stretches from as far north as Kenya south to South Africa. It is in the family Mustelidae and is the lone member of the genus Poecilogale. It has a long, slender body with short legs and a bushy tail. One of the smallest carnivorans in Africa, it measures long excluding the tail, with males generally larger than females. It has black fur over most of its body, with distinctive white bands running from the top of its head down its back, with the tail being completely white. The closest living relative of this species is the striped polecat, and it may also be related to the extinct Propoecilogale bolti.
The African striped weasel is most commonly seen in savanna and veld grasslands with termite mounds, but has also been recorded in semideserts, rainforests, fynbos and even areas used by humans such as pine plantations and agricultural land. It is a powerful digger and excavates burrows which it inhabits. Though not commonly seen, it has been listed as Least Concern on the IUCN Red List since 1996 because of its wide range and habitat tolerance. There are no known major threats to the species, though it is commonly used in local traditional medicine. Owls and domestic dogs are known to prey on it, and weasels sometimes die in fights against each other. This weasel generally flees from any perceived threats, but may try warding off its attacker with noises, fake charges or a noxious fluid sprayed from its perineal glands.
African striped weasels are specialized predators that feed almost entirely on rodents, though they occasionally eat birds as well. Even when hungry, they ignore other types of small animals and eggs provided to it as food. This animal commonly bites its prey in the back of the neck while rolling around or kicking the prey's back, likely in an attempt to dislocate the neck. Larger prey may instead be dispatched with bites to the throat, though only females have been observed doing this. This weasel rarely drinks water, only doing so in small quantities when the weather is hot. 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 two to three young tend to be born per litter after a gestation period of about 30 days.
Taxonomy and evolution
The African striped weasel was first described in 1864, when British zoologist John Edward Gray studied a skin of the animal purchased by the British Museum ten years earlier that was labeled as that of a "zorilla". He recognized that this skin was unlike that of any other known member of the mustelid family, and determined that it represented a new species which he named Zorilla albinucha. The specific name combines the Latin words meaning and meaning . Five years later, Gray published a catalogue 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 colouration of a zorilla. In 1883, another British zoologist, Oldfield Thomas, noticed that the species had significant differences in the skull compared to any known mustelid genera. He therefore established the new genus Poecilogale, the sole included species being Poecilogale albinucha. The generic name is derived from the Ancient Greek words (), meaning or , and (), meaning . Thomas' study was based on five African striped weasel specimens, four of which were kept in the British Museum, with the remaining one in the Paris Museum of Natural History.
In 1865, German naturalist Wilhelm Peters reported two mustelid specimens from Golungo Alto, Angola. He described one of them as a new species which he named Zorilla africana, and thought the other should also be considered a variety of this species. However, Austrian explorer Friedrich Welwitsch told him that the latter specimen represents the species named a year earlier as Zorilla albinucha. Welwitsch believed that the two forms were consistently different, and that even the local indigenous population refers to them by different names. 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.
Subspecies 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:
SubspeciesTrinomial authorityDescriptionRangeP. a. albinucha (Nominate subspecies)(Gray, 1864)Black with yellowish-white dorsal stripes and white tail.P. a. bechuanaeRoberts, 1931Larger than the nominate subspecies, with a green tinge at the front part of the white dorsal stripes.Vryburg, North West Province and Randfontein, Gauteng, South AfricaP. a. doggettiThomas and Schwann, 1904Similar in colour to the nominate subspecies but with longer lateral stripes compared to the middle stripe and a larger skull.UgandaP. a. lebomboRoberts, 1931Similar in colour to the nominate subspecies, but intermediate in size between it and P. a. transvaalensis.Ubombo, KwaZulu-Natal, South AfricaP. a. transvaalensisRoberts, 1926Dorsal stripes are mostly ochre-buff instead of white like in the other subspecies.Tzaneen, Limpopo, South Africa
Evolution The African striped weasel is the only species in the monotypic genus Poecilogale, which belongs in the subfamily Ictonychinae within the family Mustelidae. Ictonychinae is divided into two tribes, Ictonychini and Lyncodontini. This species is part of Ictonychini, which it shares with the striped polecat, Saharan striped polecat and marbled polecat. 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 et al., (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. It 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. Fossil specimens of Propoecilogale have been found in the Late Pliocene and Early Pleistocene-aged cave deposits of South Africa, suggesting the animal existed between 2.6 and 1.4 million years ago.
Description
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. It has small eyes, a short, broad snout, and short, rounded ears. Adults have a head-body length of , with the tail adding a further . This species exhibits sexual dimorphism, with males being larger than females. Six males sampled in KwaZulu-Natal in 1978 weighed an average of , and three sampled in the former Cape Province in 1981 had an average weight of . In comparison, and 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 splits 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 within a time span of about six weeks, and those of a different individual in captivity were reported to change from light yellow to deep buff. Staining caused by the soil in its 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 in width, whereas they only reach in others. The tail is completely white in colour and has a bushy appearance, with each of its hairs growing about . In comparison, most of the body has hairs which are around long, and those on the limbs are only long.
The head is elongated, with the skulls of some females measured in 1951 reaching an average length of and an average width of at the zygomatic arches (cheek area). The lower jaw fits tightly into the jaw joint, which greatly limits its ability to move its jaw from side to side. The carnassial teeth are sharp, and the canine teeth are long. The dentition has a dental formula of , 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 striped polecat (its closest living relative) 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 (projecting parts) of the first molar (namely the absence of a metaconid and the fusion of the metacone and paracone).
Like other mustelids, the limbs of an African striped weasel each have five digits, with each digit bearing a sharp claw. The front claws are larger and more curved than the hind claws. Each digit has an oval-shaped pad on its underside. The undersides of the paws are mostly hairless, each one having a large, four-lobed plantar 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 (adapted for running like in the Malayan and back striped weasels) and fossorial paw forms (adapted for digging like in the striped polecat). Females usually have four teats, though some have been found with six. Like many other mustelids, the African striped weasel has a developed pair of perineal scent glands.
Distribution and habitat
The African striped weasel inhabits much of Africa south of the equator, being found from the Democratic Republic of the Congo to Kenya in the north, and as far south as southern South Africa. It occurs in moist habitats with an annual rainfall of over . It is often found in savannah and veld environments where termite mounds are present, 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 (such as in southwestern South Africa in 1998), the weasel may be more widespread than previously thought. It commonly lives below elevation, but may occasionally be found as high as .