| African striped weasel | |
|---|---|
 | |
| Captive adult individual | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Mustelidae |
| Subfamily: | Ictonychinae |
| Genus: | Poecilogale Thomas, 1883 |
| Species: | P. albinucha |
| Binomial name | |
| Poecilogale albinucha (Gray, 1864) | |
| Subspecies | |
Seetext | |
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| Range of the African striped weasel | |
| Synonyms[2][3][4] | |
TheAfrican striped weasel (Poecilogale albinucha), also known as thewhite-naped weasel,striped weasel orAfrican weasel, is a smallmammal native tosub-Saharan Africa, where its range stretches from as far north asKenya south toSouth Africa. It is in the familyMustelidae and is thelone member of thegenusPoecilogale. It has a long, slender body with short legs and a bushy tail. One of the smallestcarnivorans in Africa, it measures 24 to 35 cm (9.4 to 13.8 in) long excluding the tail, with malesgenerally larger than females. It has blackfur 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 thestriped polecat, and it may also be related to the extinctPropoecilogale bolti.
The African striped weasel is most commonly seen insavanna andveld grasslands withtermite mounds, but has also been recorded insemideserts,rainforests,fynbos and even areas used by humans such aspine plantations and agricultural land. It is a powerful digger and excavatesburrows which it inhabits. Though not commonly seen, it has been listed asLeast Concern on theIUCN 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 localtraditional medicine. Owls and domestic dogs are known toprey 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 itsperineal glands.
African striped weasels are specialized predators that feed almost entirely onrodents, though they occasionally eatbirds 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 anocturnal andsolitary 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 perlitter after agestation period of about 30 days.
The African striped weasel was first described in 1864, when British zoologistJohn Edward Gray studied a skin of the animal purchased by theBritish 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 themustelid family, and determined that it represented a new species which he namedZorilla albinucha.[5] Thespecific name combines theLatin wordsalbi meaning'white' andnucha meaning'nape'.[2] 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 genusMustela asMustela albinucha, commenting that it only has the colouration of a zorilla.[4] 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 genusPoecilogale and renamed the species asPoecilogale albinucha. Thegeneric name is derived from theAncient Greek wordspoikilos (ποικίλος), meaning'particoloured' or'cunning', andgalē (γαλῆ), meaning'weasel'. Thomas' study was based on five African striped weasel specimens, four of which were kept in the British Museum, with the remaining one in theParis Museum of Natural History.[3]
In 1865, German naturalistWilhelm Peters reported two mustelid specimens fromGolungo Alto, Angola. He described one of them as a new species which he namedZorilla africana, and thought the other should also be considered a variety of this species. However, Austrian explorerFriedrich Welwitsch told him that the latter specimen represents the species named a year earlier asZorilla albinucha. Welwitsch believed that the two forms were consistently different, and that even the local indigenous population refers to them by different names.[6] In the same year, Portuguese zoologistJosé Vicente Barbosa du Bocage studied two skins and a skeleton of African striped weasels fromCalandula, Angola and proposed that the animal'sscientific name be changed toZorilla flavistriata.[7] BothZorilla africana andZorilla flavistriata are no longer deemedvalid names, and are now consideredjunior synonyms ofPoecilogale albinucha.[2]
A number of African striped weaselsubspecies 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 ismonotypic and that all proposed subspecies should be considered invalid.[2][8] The following five subspecies were recognized in the third edition ofMammal Species of the World, published in 2005:[9]
| Subspecies | Trinomial authority | Description | Range |
|---|---|---|---|
| P. a. albinucha | (Gray, 1864) | Black with yellowish-white dorsal stripes and white tail.[5] | |
| P. a. bechuanae | Roberts, 1931 | Larger than the nominate subspecies, with a green tinge at the front part of the white dorsal stripes.[10] | Vryburg,North West Province andRandfontein,Gauteng, South Africa[11] |
| P. a. doggetti | Thomas and Schwann, 1904 | Similar in colour to the nominate subspecies but with longer lateral stripes compared to the middle stripe and a larger skull.[12] | Uganda[12] |
| P. a. lebombo | Roberts, 1931 | Similar in colour to the nominate subspecies, but intermediate in size between it andP. a. transvaalensis.[10] | Ubombo,KwaZulu-Natal, South Africa[11] |
| P. a. transvaalensis | Roberts, 1926 | Dorsal stripes are mostlyochre-buff instead of white like in the other subspecies.[13] | Tzaneen,Limpopo, South Africa[11] |
The African striped weasel is the only species in the monotypic genusPoecilogale, which belongs in the subfamilyIctonychinae within the familyMustelidae. Ictonychinae is divided into twotribes, Ictonychini and Lyncodontini. This species is part of Ictonychini, which it shares with thestriped polecat,Saharan striped polecat andmarbled polecat.Genetic analyses indicate that the closest living relative of the African striped weasel is the striped polecat, with the two being recovered assister taxa in multiple studies.[14][15][16] A study published in 2008 suggested that the lineages of these two speciesdiverged 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.[14][15] The followingcladogram shows the position of the African striped weasel among its closest living relatives according to Gray et al., (2022):[16]
| Ictonychinae |
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A fossil species,Propoecilogale bolti, was originally named as a member of the genusIctonyx, but has been placed in a separate genus since 1987. It shows features in its skull and teeth that are intermediate betweenIctonyx andPoecilogale, and has been suggested to be an ancestor of the African striped weasel.[17] Fossil specimens ofPropoecilogale have been found in theLate Pliocene andEarly Pleistocene-aged cave deposits of South Africa, suggesting the animal existed between 2.6 and 1.4 million years ago.[18][19]
One of the smallestcarnivorans found in Africa (along with thedwarf 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.[2][20] 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 exhibitssexual dimorphism, with males being larger than females. Six males sampled inKwaZulu-Natal in 1978 weighed an average of 339 g (12 oz), and three sampled in the formerCape 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.[2][21] 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.[2][22] 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 deepbuff.[23] Staining caused by the soil in its habitat may cause these bands to appear red, grey or yellow, particularly in periods of rain.[8] The width of the bands varies between individuals; some specimens found inBotswana 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.[2]
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 thezygomatic arches (cheek area). The lower jaw fits tightly into thejaw joint, which greatly limits its ability to move its jaw from side to side. Thecarnassial teeth are sharp, and the canine teeth are long.[2] Thedentition has adental formula of3.1.2.13.1.2.1, that is, threeincisors, onecanine, twopremolars and onemolar 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.[17][24][25] The absence of those teeth is aderived trait differing from theancestral condition retained by the striped polecat, as are some features of thecusps (projecting parts) of the first molar (namely the absence of ametaconid and the fusion of themetacone andparacone).[17]
Like othermustelids, the limbs of an African striped weasel each have fivedigits, with each digit bearing a sharp claw. The front claws are larger and more curved than the hind claws.[2][20] 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 theMalayan weasel andback-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 betweencursorial paw forms (adapted for running like in the Malayan and back striped weasels) andfossorial paw forms (adapted for digging like in the striped polecat).[26] Females usually have fourteats, though some have been found with six. Like many other mustelids, the African striped weasel has a developed pair ofperinealscent glands.[2]
The African striped weasel inhabits much of Africa south of theequator, being found from the Democratic Republic of the Congo to Kenya in the north, and as far south as southern South Africa.[1] It occurs in moist habitats with an annual rainfall of over 60 cm (24 in). It is often found insavannah andveld environments wheretermite mounds are present, with a 1978 survey revealing that 75% of African striped weasel sightings were made in suchgrasslands.[2][8] However, the species appears to tolerate a wide range of habitats, having also been seen insemideserts,rainforests,fynbos andpine 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.[1][20][21] It commonly lives below 1,500 m (4,921 ft) elevation, but may occasionally be found as high as 2,200 m (7,218 ft).[2][8]
The African striped weasel is a mostlynocturnal animal, though it can sometimes be found at dawn or dusk. This species walks with a distinctive gait, with the body stretched out or arched while the snout 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.[8] These weasels are effective diggers and construct their ownburrows, sometimes working in pairs to do so, using their front limbs to dig into the ground and their hind limbs to kick soil backwards.[2][21] However, they may sometimes rest in natural cavities such as hollow logs or rock crevices. They defecate in well-definedlatrine 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.[2][23][27] 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.[28]
African striped weasels aregenerally 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 bristling up the hair on their tails, making short cries and fake charges, and then escalating to fighting with bites, thrashing, and aggressive shrieks if neither individual retreats.[2] The species has been identified as making six differentcalls. Apart from the warning and aggressive calls, 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.[27][29]
African striped weasels are specialistpredators known to hunt small mammals and birds, with the vast majority of their diet consisting ofrodents of their own size or smaller, and will travel into the burrows of rodents to hunt them.[28][2] While they occasionally feed on reptiles, insects, and eggs, in experiments conducted during the 1970s, captive striped weasels did not attack or eat several genera ofinvertebrates (including various insects), reptiles, amphibians and chicken eggs offered to them, even while hungry.[28][2] The weasels hunt primarily by scent, attacking prey with a sudden lunge and biting onto the back of the neck. After the initial strike, they roll around and kick the prey animal's back orpelvic region, perhaps in order to dislocate the prey's neck (as suggested in 1978 by South African researcher David T. Rowe-Rowe). 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. Unlike the related striped polecat, this species does not use its front limbs to stabilize its food while eating. 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.[28]
They do not drink frequently, 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 almost any water during this time, only occasionally drinking small amounts of water during hot weather.[28]
The breeding season of the African striped weasel is extensive, lasting from spring to the end of summer. Thetestes of the male remain large from September to April (spring to early autumn) and are shrunken for the rest of the year. A soft chattering sound, believed to be a greeting call, is emitted by the male when courting a female during this time. If the female is receptive, she may express her receptiveness by moving around him. The male will then gently chew on her cheek, sniff hervulva and hold onto her neck from behind. During mating, the male continues to grip the female's neck from behind while clutching his forelimbs around her pelvic region. The duration ofcopulation is variable and can be as short as 27 minutes, though it typically lasts between 60 and 80 minutes.[30] At least three bouts of copulation can occur within a day. Females raise the young with no aid from the males and give birth to one litter per year of two or three young after agestation period of about 30 days, though they may have a second litter if the first is lost early.[2]
Birth takes place in a burrow during the daytime, and the mother eats theplacenta afterwards. The newborn young weigh just 4 g (0.14 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 which stretches 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 andpinnae (ear flaps) already being present. Their skin becomes dark at seven days old, and the prominent black and white colouration of the species develops at 28 days old. Theirmilk canine teeth grow out at five weeks, at which point they begin eating the soft parts of prey killed by their mother, with permanent canines growing at 11 weeks before the milk canines are shed. Their eyes open at an age of 51 to 54 days. By 11 weeks of age they areweaned (stop drinking milk), and they start killing their own prey at 13 weeks. They reach full adult size at 20 weeks, and are sexually mature at eight months.[30]
The lifespan of the African striped weasel is short, with captive individuals recorded to only live for five or six years.[2][31]Tuberculosis of the spleen is a common cause of death in some captive weasels.[22] They are also known to kill each other inintraspecific fights (fights with others of their species). Documented predators of wild individuals include owls anddomestic dogs, with humans also sometimes trapping and killing them when they visit chicken houses or to use them intraditional medicine.[2][23] Some fall victim tovehicular collisions, as evidenced by roadkill carcasses found in agricultural areas.[1] The tapewormTaenia brachyacantha is also a known parasite of the species.[32]
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 fails, the weasel may spray a yellowish, musky fluid from its perineal glands that can be ejected up to 1 m (3 ft 3 in) away.[2][23] 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 ofskunks andstriped polecats.[27]
TheInternational Union for Conservation of Nature (IUCN) first assessed the African striped weasel in 1996 and listed it as aLeast Concern species on theIUCN Red List, with the same listing given in subsequent assessments in 2008 and 2015, citing that 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". It is not known 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.[1] Modification of the weasel's preferred grassland habitat due to human activities such as agriculture and livestock grazing may also pose a threat.[2]
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