Black-backed jackal
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| Black-backed jackal[1] Temporal range: Pliocene[2] - Recent | |
|---|---|
 | |
| Cape jackal (Canis m. mesomelas), Western Etosha, Namibia | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Canidae |
| Genus: | Canis |
| Species: | C. mesomelas |
| Binomial name | |
| Canis mesomelas (Schreber, 1775) | |
| Subspecies | |
2 ssp., see text | |
 | |
| Black-backed jackal range | |
The black-backed jackal (Canis mesomelas), also known as the silver-backed or red jackal,[4]is a species of jackal which inhabits two areas of the African continent separated by roughly 900 km. One region includes the southern-most tip of the continent, including South Africa,Namibia, Botswana, and Zimbabwe. The other area is along the eastern coastline, includingKenya, Somalia, and Ethiopia. It is listed by the IUCN as least concern, due to its widespread range and adaptability, although it is still persecuted as a livestock predator and rabies vector.[3]The fossil record indicates the species is the oldest extant member of the genus Canis.[2] Although the most lightly built of jackals, it is the most aggressive, having been observed to singly kill animals many times its own size, and its intrapack relationships are more quarrelsome.[5]
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[edit]Evolution
The black-backed jackal is an exceptionally stable and ancient form of canid, with many fossils dating as far back as the Pleistocene epoch.[6] Fossil jackals discovered in the Transvaal cave are roughly the same size as their descendents, though their nasal bones differ in size.[5] Although numerous fossils dating back to two million years ago have been found in Kenya, Tanzania, and South Africa,[5] they are entirely absent in Ethiopia, indicating the species has never expanded past sub-Saharan Africa.[7] Mitochondrial DNA analyses display a large sequence divergence in black-backed jackals from other jackal species, indicating they diverged 2.3–4.5 million years ago.[5]
[edit]Physical description
Black-backed jackals are small, foxlike canids which measure 38–48 cm in shoulder height and 68-74.5 cm in length. The tail measures 30–38 cm in length.[6]Weight varies according to location; East African jackals weigh 7-13.8 kg (15-30 lb). Male jackals in Zimbabwe weigh 6.8-9.5 kg (15-21 lb), while females weigh 5.4–10 kg (12-22 lb).[8] Their skulls are elongated, with pear-shaped braincases and narrow rostra.[7] The black-backed jackal's skull is similar to that of the side-striped jackal, but is less flat, and has a shorter, broader rostrum. Its sagittal crest and zygomatic arches are also heavier in build. Its carnassials are also larger than those of its more omnivorous cousin.[9] Black-backed jackals are taller and longer than golden jackals, but have smaller heads.[5]
The general colour is reddish-brown to tan, while the flanks and legs are redder. Males tend to be more brightly coloured than females, particularly in their winter coat. The back is intermixed with silver and black hairs, while the underparts are white.[8] Their tails have a black tip, unlike side-striped jackals, which have white-tipped tails.[5] The back of the ears are light yellowish-brown, well covered with hair without and within.[10] The hair of the face measures 10–15 mm in length, and lengthens to 30–40 mm on the rump. The guard hairs of the back are 60 mm on the shoulder, decreasing to 40 mm at the base of the tail. The hairs of the tail are the longest, measuring 70 mm in length.[7]
[edit]Behaviour
[edit]Social behaviour and reproduction
Jackals usually den in holes made by other species, though they will occasionally dig their own; females will dig tunnels 1–2 metres in depth with a 1-metre-wide entrance. Black-backed jackals are monogamous and territorial animals, whose social organisation greatly resembles that ofgolden jackals. However, unlike the latter species, the assistance of elder offspring in helping raise the pups of their parents has a greater bearing on pup survival rates.[8] During the mating season, they become increasingly more vocal and territorial, with dominant animals preventing same-sex subordinates from mating through constant harassment. In southern Africa, mating occurs from late May to August, with a 60 day gestation period. Pups are born from July to October. Summer births are thought to be timed to coincide with population peaks of vlei rats and four-striped grass mice, while winter births are timed for ungulate calving seasons.[7] Litters usually consist of three to six pups. For the first three weeks of their lives, the pups are kept under constant surveillance by their mother, while the father and elder offspring provide food. They typically leave the den after three weeks, and become independent at six to eight months.[8] Pups have drab coloured coats, which only reach full intensity at the age of two years.[7] Unlike golden jackals, which have comparatively amicable intrapack relationships, black-backed jackal pups become increasingly quarrelsome as they age, and establish more rigid dominance hierarchies. Dominant cubs will appropriate food, and become independent at an earlier age.[8]
[edit]Diet
Black-backed jackals are omnivores, which feed on invertebrates, such as beetles, grasshoppers,crickets, termites, millipedes, spiders and scorpions. They will also feed on mammals, such asrodents, hares and young antelopes up to the size of topi calves. They will also feed on carrion,lizards, and snakes. A pair of black-backed jackals in the Kalahari desert was observed to kill and devour a kori bustard and, on a separate occasion, a black mamba via prolonged harassment of the snake and crushing of the snake's head.[11] Black-backed jackals will occasionally feed on fruits and berries.[8] In coastal areas, they will feed on beached marine mammals, seals, fish andmussels.[7] A single jackal is capable of killing a healthy adult impala.[12] Adult dik dik andThompson's gazelles seem to be the upper limit of their killing capacity, though they will target larger species if they are sick, with one pair having been observed to harass a crippled bullrhinoceros. They typically kill tall prey by biting at the legs and loins, and will frequently go for the throat.[6] In Serengeti woodlands, they feed heavily on African grass rats. In East Africa, during thedry season, they hunt the young of gazelles, impalas, topi, tsessebe and warthogs.[8] In South Africa, black-backed jackals frequently prey on antelopes (primarily impala and springbok and occasionally duiker, reedbuck and steenbok), carrion, hares, hoofed livestock, insects, and rodents. They will also prey on small carnivores, such as mongooses, polecats and wild cats. On the coastline of the Namib Desert, jackals feed primarily feed on marine birds (mainly Cape andwhite-breasted cormorants and jackass penguins), mammals (including Cape fur seals), fish, and insects.[5]
In the Ngorongoro Crater, where both black-backed and golden jackals are found in equal numbers, the former species congregates at carcasses in large numbers far more readily, and is bolder in approaching larger predators.[8]
[edit]Interspecific predatory relationships
Eagles are the primary threat to pups; bateleur eagles will carry off pups up to the age of 10 weeks, while the larger martial eagles will even target subadults.[8] Spotted hyenas and golden jackals will also kill unprotected pups.[7]
Although smaller than side-striped jackals, the more aggressive black-backed jackals have been observed to dominate them in direct encounters.[13]
[edit]Vocalisations
Sounds made by black-backed jackals include yelling, yelping, woofing, whining, growling and cackling. When calling to one another, they emit an abrupt yelp followed by a succession of shorter yelps. Jackals of the same family will answer each others calls, while ignoring those of strangers. When threatened by predators, they yell loudly. Black-backed jackals in southern Africa are known to howl much like golden jackals. They woof when startled, and cackle like foxes when trapped.[8]
[edit]Habitat
In their northeastern range, black-backed jackals inhabit habitat zones intermediate to the grasslands favoured by golden jackals and the woodlands favoured by side-striped jackals. In the Serengeti, they predominate in Acacia and Commiphora woodlands, while the golden species limits itself to open plains. In their southern range, where golden jackals are absent, black-backed jackals are found in more open and arid habitats, though preferring areas with scattered brush.[8]
[edit]Subspecies
There are two recognized subspecies of this canid:[1]
| Subspecies | Trinomial authority | Description | Range | Synonyms |
|---|---|---|---|---|
| Cape jackal Canis m. mesomelas  | Schreber, 1775 | Nominate subspecies | Cape of Good Hope, northward to Angola, Zimbabwe, and southern Mozambique | achrotes(Thomas, 1925) arenarum(Thomas, 1926) variegatoides (A. Smith, 1833) |
| East African jackal Canis m. schmidti  | Noack, 1897 | Differing from C. m. mesomelas by its larger size and not being known to howl,[8] it also has differently shaped teeth due to its more carnivorous diet, and is less sexually dimorphic.[5] | Southern Ethiopia, southern Sudan, Somalia, Kenya, Uganda, and northern Tanzania | elgonae (Heller, 1914) mcmillani(Heller, 1914) |
[edit]Diseases and parasites
Black-backed jackals can carry diseases such as rabies, canine parvovirus, canine distemper, canine adenovirus, Ehrlichia canis and African horse sickness. Jackals in Etosha National Park may carry anthrax. Black-backed jackals are major rabies vectors, and have been associated with epidemics, which appear to cycle every four to eight years. Jackals in Zimbabwe are able to maintain rabies independently of other species. Although oral vaccinations are effective in jackals, the long-term control of rabies continues to be a problem in areas where stray dogs are not given the same immunisation.[5]
Jackals may also carry trematodes such as Athesmia, cestodes such as Dipylidium caninum, Echinococcus granulosus, Joyeuxialla echinorhyncoides, J. pasqualei, Mesocestoides lineatus, Taenia erythraea, T. hydatigena, T. jackhalsi, T. mulitceps, T. pungutchui, and T. serialis. Nematodes carried by black-backed jackals include Ancylostoma braziliense, A. caninum, A. martinaglia, A. somaliense, A. tubaeforme, and Physaloptera praeputialis, and protozoans such as Babesia canis, Ehrlichia canis, Hepatozoon canis, Rickettsia canis,Sarcocytis spp., Toxoplasma gondii, and Trypanosoma congolense. Mites may cause sarcoptic mange. Tick species include Amblyomma hebraeum, A. marmoreum, A. nymphs, A. variegatum, Boophilus decoloratus, Haemaphysalis leachii, H. silacea, H. spinulosa, Hyelommaspp., Ixodes pilosus, I. rubicundus, Rhipicephalus appendiculatus, R. evertsi, R. sanguineus, and R. simus. Flea species includeCtenocephalides cornatus, Echidnophaga gallinacea, and Synosternus caffer.[5]
[edit]Relationships with humans
[edit]In folklore
Black-backed jackals feature prominently in the folklore of the Khoikhoi, where it is often paired with the lion, whom it frequently outsmarts or betrays with its superior intelligence. One story explains that the black-backed jackal gained its dark saddle when it offered to carry the sunon its back.[14]
[edit]Livestock predation
Black-backed jackals will occasionally hunt domestic animals, including dogs, cats, pigs, goats, sheep, and poultry, with sheep tending to predominate. They rarely target cattle, though cows giving birth may be attacked. Jackals can be a serious problem for sheep farmers, particularly during the lambing season. Sheep losses to black-backed jackals in a 440 km study area in KwaZulu-Natal consisted of 0.05% of the sheep population. Of 395 sheep killed in a sheepfarming area in KwaZulu-Natal, 13% were killed by jackals. Jackals usually kill sheep via a throat bite, and will begin feeding by opening the flank and consuming the flesh and skin of the flank, heart, liver, some ribs, haunch of hind leg, and sometimes the stomach and its contents. In older lambs, the main portions eaten are usually heart and liver. Usually only one lamb per night is killed in any one place, but sometimes two and occasionally three may be killed.[5] In sheep farming areas, black-backed jackals will time their pup births to coincide with the lambing season. The oral history of the Khoikhoi indicates they have been a nuisance to pastoralists long before European settlement. South Africa has been using fencing systems to protect sheep from jackals since the 1890s, though such measures have mixed success, as the best fencing is expensive, and jackals can easily infiltrate cheap wire fences.[15]
[edit]Hunting
Main article: Jackal coursing
Due to livestock losses to jackals, many hunting clubs were opened in South Africa in the 1850s. Black-backed jackals have never been successfully eradicated in hunting areas, despite strenuous attempts to do so with dogs, poison and gas.[7] Black-backed jackal coursing was first introduced to the Cape Colony in the 1820s by Lord Charles Somerset who, as well as an avid fox hunter, sought a more effective method of managing jackal populations, as shooting proved ineffective.[16]Coursing jackals also became a popular pastime in the Boer Republics,[17] particularly in Orange Free State, where it was standard practise to flush them from their dens with terriers and send greyhounds in pursuit. This was fraught with difficulty, however, as jackals were difficult to force out of their earths (dens), and usually had numerous exits from which to escape.[18] This method is still used by farmers in Free State.[19] In the western Cape in the early 1900s, dogs bred by crossing foxhounds, lurchers and borzoi were used.[15]
Spring traps with metal jaws were also effective, though poisoning by strychnine became more common by the late 19th century. Strychnine poisoning was initially problematic, as the solution had a bitter taste, and could only work if swallowed. Consequently, many jackals learned to regurgitate poisoned baits, thus inciting wildlife managers to use the less detectable crystal strychnine rather than liquid. The poison was usually placed within sheep carcasses or in balls offat, with great care being taken to avoid leaving any human scent on them. Black-backed jackals were not a popular quarry in the 19th century, and are rarely mentioned in hunter's literature. By the turn of the century, jackals became increasingly popular quarry as they encroached upon human habitations after sheep farming and veld burning diminished their natural food sources. Although poisoning had been effective in the late 19th century, its success rate in eliminating jackals waned in the 20th century, as jackals seemed to be learning to distinguish poisoned foods.[15] Today, professional South African hunters commonly lure jackals by using recorded jackal calls.[4]
The Tswana people often made hats and cloaks out of black-backed jackal skins. Between 1914 and 1917, 282,134 jackal pelts (nearly 50,000 a year) were produced in South Africa. Demand for pelts grew during the First World War, and were primarily sold in Cape Town andPort Elizabeth. Jackals in their winter fur were in great demand, though animals killed by poison were less valued, as their fur would shed.[15]
