Sunday, 8 March 2015

The Dog Family: Three Jackals and a Wolf

Black-backed jackal
The genus Canis groups together all the most wolf-like of the wolf-like dogs. It includes the grey wolf (which itself includes both the domestic dog and the dingo), the coyote, and, assuming we recognise it as distinct, the red wolf. All of the other living species in the genus have, at one point or another, been called "jackals". Biologically speaking, then, the term "jackal" doesn't really mean anything - it's just what you've got left over once you've left out the wolves and coyotes. But, it has to be said that the three species we still call jackals today do have a certain physical similarity, and it's not hard to see why the fine details of their genetic relationship had us fooled.

Perhaps the most visibly distinctive of the jackals is the black-backed jackal (Canis mesomelas), sometimes called the "silver-backed jackal", since, aside from a stripe down each flank, the back can hardly be described as pure black. Black-backed jackals have a somewhat odd distribution. They are common in southern Africa, from southern Angola and Mozambique down to the Cape region, but they're also found in eastern Africa, from Tanzania to Eritrea, and throughout the Horn of Africa.

These two areas to not adjoin one another, and there are no black-backed jackals in, for example, Malawi or northern Mozambique. Whilst they must once have ranged over the area in between, today, the two populations have been separated from one another for long enough that they are distinct subspecies, able and willing to interbreed should they ever meet up, but genetically and physically different enough that they can be reliably told apart.

Black-backed jackals live in open terrain, where it is relatively easy to see prey animals, venturing perhaps into woodland savannah, and up to 3,000 metres (10,000 feet) in the Drakensburg Mountains, but more commonly found out on the open grasslands or in desolate semi-deserts. Or, in modern times, farmland, where they can present a threat of transmitting rabies. They have something of a reputation for eating carrion, and certainly won't waste the opportunity to eat something that's already dead but hasn't yet gone completely stinky. For that matter, they also cache food if they happen to obtain too much of it, but, of course, they do eat fresh prey, too.

Not being as large as the major African predators, such as lions and hyenas, they're mostly going for smaller animals. Beyond that, they honestly don't seem to care much what they eat, so long as it's around: in practice, rodents, birds, and young antelope form the bulk of their diet. They are often found in coastal areas, and along the Skeleton Coast in Namibia, over three-quarters of their food intake seems to consist of cormorants. However, in the same area they are also known to eat young or injured seals, with large numbers gathering around - and squabbling over - the bigger carcasses.

Like many dogs, black-backed jackals live and hunt in mated pairs, and are seemingly faithful for long periods. In most places, they are not great pack hunters, though, which also limits the size of the prey they can take down. But that's not a universal rule, and pack behaviour is not entirely unknown. Sometimes it's little more than traipsing around after a hyena in the hope that there'll be some scraps left over, but, in Botswana, packs of jackals have been seen cooperating to take down adult impala, and sometimes even larger antelopes.

Other than that, black-backed jackals are, as might be expected, territorial animals, with each mated pair defending its own patch of hunting ground from rivals. They do, however, seem less bothered by sub-adult jackals than they are by other mated pairs, and may share territory with them. This may well because these sub-adults can help out with rearing pups, and pairs with access to this sort of assistance are more likely to rear their own pups to adulthood. When around a third of pups die in infancy, and 20% of litters are lost altogether, such an advantage can be quite significant.

Mated pairs mark out their territory in the usual way that dogs are inclined to. Given the absence of lampposts on the veldt, they will typically pick any rock or other visibly obvious location, but they have also been reported to preferentially leave their marks on piles of elephant dung. (Rhino dung is apparently even better, but sadly in short supply these days). Presumably, the dung is smelly enough that other jackals will notice it from even further away than they'll notice a rock, and can approach closer to find the more subtle message left with it.

It's not all smell, though, since black-backed jackals do, like wolves, howl, both to warn others off, and to locate their mates. In addition, they have a distinctive multi-syllable yelp that warns of danger - there isn't much that eats jackals, but leopards, for instance, will certainly try. Other yelps, whines, and barks have also been recorded, many of them used as signals to pups. They have also been reported to make an unusual submissive gesture, in which the subordinate individual rests his front legs on the rump of the other.

Side-striped jackal
Moving north, however, we come to the side-striped jackal (Canis adustus). These are closely related to the black-backed kind, and the two animals look rather similar. Although there are other, subtle, differences, the easiest way to tell them apart is by the white stripe along the flanks of adults of the side-striped species. This is, however, far less obvious in younger individuals, making differentiation difficult.

Side-striped jackals are very widespread, being found across most of Africa south of the Sahara, avoiding only the dense equatorial jungles and the more barren southern and eastern regions where their black-backed kin are found. Having said that, there are places in East Africa, from Mozambique to Ethiopia, where both species live side by side. Naturally having less of a preference for open spaces, where the two live together, the side-striped jackals cede such ground to their aggressive black-backed kin, and end up being forced into denser woodlands where the others will not follow.

This is less of a problem than it might be, because side-striped jackals seem to have an even broader tolerance for varied diets than the black-backed species. In short, they will eat just about anything, and, while they clearly prefer meat, as much as a third of their diet can consist of plums, berries, and other fruit. Indeed, it has even been suggested that, at least where they compete with black-backed jackals, the side-striped kind spend most of their day actively looking for fruit, and only eat animals that they happen to come across while doing so.

Side-striped jackals are also more tolerant of humans, and therefore more likely to approach towns and safari camps, especially where black-backed jackals force them off the grasslands. Here they can dine on refuse and also become more nocturnal, mostly active when the humans themselves are asleep. In most other respects, the two species are similar, although the side-striped jackals may be more likely to travel in family groups, especially where food is plentiful.

Golden jackal
The north of Africa, however, belongs to the golden jackal (Canis aureus), an animal more closely related to wolves and coyotes than it is to the other two jackals. Physically, though, they do have a similar size and build to the other jackals, and, while, as their name suggests, they are mostly a uniform golden-tan colour, some do have faint dark markings on the back resembling the more striking ones of their southerly namesakes.

Golden jackals are found across the arid north of Africa, and overlap with the other species in the east. Outside of that continent, they are found across most of the deserts of the Middle East, and across southern Asia as far east as Thailand and as far south as Sri Lanka. Golden jackals are even found in Europe, where they were once common across the whole of the Balkans, and have been seen as far afield as Hungary, north-eastern Italy, and even Austria on occasion. There are at least seven subspecies, and perhaps as many as twelve, although how "real" all of these are isn't completely clear. (And that's leaving aside the fact that, not so long ago, one of them turned out to be a wolf).

As one might imagine given this vast range, golden jackals are adaptable animals, whose only real limitation seems to be a dislike of cold winters. They inhabit almost every warm habitat type from semi-desert to dense forest, and from marshland to mountains, and, in places like Bangladesh and the Golan Heights, clearly aren't too worried by intensive agriculture or semi-urban habitats, either. Like other jackals, they will eat whatever they can find, with carrion and, where it is available, human left-overs often forming a significant part of the diet.

Exactly what they are eating varies, therefore, depends largely on where they live. Rodents are, as one might expect, their most common prey, although the rodents we're talking about will vary from place to place. In the semi-desert regions of central Niger, they have been reported to feed primarily on plants and invertebrates, albeit allegedly topping this up with the odd bit of domestic livestock. In India, on the other hand, they dig gerbils out of their burrows, which may actually be a positive for agriculture.

Even solitary jackals will sometimes take down flamingos or newborn gazelles, but by hunting cooperatively, some jackals have tackled even larger animals - especially, to be fair, if the target is already injured or infirm. Even so, small packs of golden jackals have been seen attacking antelopes and (when they make the mistake of coming down out of the trees) langur monkeys.

Perhaps unsurprisingly, a sufficiently large carcass may attract quite large packs of scavengers, but, while most spend the majority of their lives as a single mated pair, with the male aggressively ensuring it stays that way, the social system of golden jackals seems quite flexible. Given the right circumstances, they can, at least temporarily, gather into groups of as many as twenty individuals, some of which go as far as to cooperatively defend and mark a loosely defined territory.

Like their relatives, golden jackals typically breed once a year, in their case normally in the winter, although the exact month varies depending on when in the year prey animals will become most common in their area. Females apparently spend as much as four weeks trying to get the male to pay attention to them, and, once he does, give birth to a litter of up to eight pups after a 63-day pregnancy. They prepare a den before the birth, although in more inhabited areas, they'll happily pinch a drainage pipe if it means they don't have to do any digging. The pups are weaned at two to four months, and leave home before the year is out.

Ethiopian wolf
There is one further species sometimes described as a jackal, specifically the "Simien jackal" (it's sometimes even called a fox, although it manifestly isn't one, so goodness knows why). Since, however, it neither particularly looks like a jackal, nor acts much like one, these days it is more common to refer to it as the Ethiopian wolf (Canis simensis).

It's not hard to distinguish Ethiopian wolves from jackals; they're quite a bit larger, and a different colour. Really, their only connection to jackals is that they, too, live in Africa. They are also far less widespread than any of the jackal species, and have a specialised lifestyle quite at odds with the adaptability of those animals. More widespread when they first appeared during the Ice Ages, they are now found only in the mountains of central Ethiopia, always above 3,000 metres (10,000 feet), and in relatively open, typically rugged, terrain.

As human agriculture has advanced, they have found themselves forced ever higher up the mountains, and, in many areas, they have simply run out of places to retreat to and have gone locally extinct. Seven populations still survive, each isolated from the others, in different parts of the mountain range. Formally listed as an endangered species, it is thought that less than 500 adults remain, mostly in the Bale Mountains at the southern end of their range.

Whereas jackals will eat anything, Ethiopian wolves are so restricted because they have very specific dietary requirements, feeding on almost nothing but diurnal rodents. Indeed, over 85% of their diet seems to consist of just three species, with giant mole-rats as their apparent favourite. (The giant mole-rat is, incidentally, not closely related to the more famous naked sort). For the most part, they chase them when they come above ground, but they also dig into burrows, sometimes to some considerable depth, kicking up mounds of earth in their eagerness.

It's not quite that they can't eat anything else, however, and, on the rare occasions when they hunt in packs they can take down small antelope and the like. They'll also go for carrion, if there happens to be any about, and local legend says that they follow pregnant horses and sheep around in order to eat the afterbirth. But, on the whole, they don't seem very keen on these alternatives, preferring to focus on rats, which don't require much in the way of cooperative hunting.

Despite this, they are pack animals, living in more or less permanent groups of up to a dozen or so individuals, rather than the larger, but looser, assemblages that are the best jackals can muster. Packs are based around a mated pair, but include other adults as well, and, while they may hunt alone, everyone joins in scent marking and howling to identify their shared territory. Unusually (although not uniquely among canids, as we will see in a later post) it is the males who stay with the pack when they reach adulthood, and the females who wander off in search of pastures new. Among other species, a "lone wolf" is almost always male, on the prowl for sexual partners, but here, it is the females who take that role.

This, then, is an unusual wolf, one similar in many ways to its better-known relatives, but with quite a different lifestyle. Its gene pool is shrinking, and one population has even begun cross-breeding with domestic dogs for lack of any alternative. Depending on what you think about the red wolf, it may even be the most endangered member of the dog family alive today.

And so, that completes our review of the genus Canis. However, there are two other species that fall within the same general branch of the dog family tree, and it is to them that I will turn next, before heading on to look at the foxes and their kin...

[Photos by Hans Hillewaert, Thomas A. Hermann, Artemy Voikansky, and "Laika ac", from Wikimedia Commons, cladogram adapted from Lindblad-Toh et al, 2005 and Bardeleben et al, 2005]

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