Sunday, 19 June 2016

Bovines: Will the Real Buffaloes Please Stand Up?

African buffalo
Outside of North America, the term "buffalo" refers not to the bison, but to two (or more) species of bovine native to Africa and Asia. In the wild, by far the more common of the two is the African buffalo (Syncerus caffer), which has the distinction of being the only non-domesticated species of truly cow-like bovine that isn't even slightly endangered.

African buffalo are very numerous, and found across wide swathes of Africa south of the Sahara. This includes a fair number of different habitats, and African buffalo vary not just in their habits and preferences, but in their physical appearance, across that range. They were first described scientifically by Swedish naturalist Anders Sparrman in 1779, based on an animal found at Algoa Bay, near present-day Port Elizabeth in South Africa. Given the association with that general part of the world, the alternative name of "Cape buffalo" is often used for the animal, although that seems a little restrictive for something so widespread to me.

At any rate, over the next century and a half, scientists racked up descriptions of an impressive number of subspecies - by 1913, at least 21 were recognised. In the hundred years since, that number has steadily declined as it has become clear just how tiny the differences between some of them were. Even now, the question isn't entirely settled. There is agreement that there at least three subspecies, but there might be more, and it has been also been argued that some of them are genetically distinct enough to be full species in their own right.

In general, African buffalo are large animals, although noticeably smaller than bison, with the largest bulls standing about 175 cm (5'9") at the shoulder, and weighing up to 900 kg (1 US ton). Unlike bison, they have short, mostly black, hair on their bodies and heavy curved horns that meet in the middle, forming a solid shield of horny material over their foreheads. This is the origin of their generic name Syncerus, given to them by Brian Houghton in 1847, and literally meaning "fused horns". They are generally woodland dwelling animals, but require open space, rather than densely packed trees, and, since they're so big, a fair amount of water, meaning that they congregate near rivers in the drier parts of the continent.

As one might expect, buffalo feed mainly on grass, although, as the dry season wears on there's increasingly little of it left that's still edible, forcing the animals to switch to other greenery. Given the choice, though, buffalo can be fairly picky, eating the grasses that have the greenest leaves and the smallest amount of fibrous stems. The need to do so also affects their movements over time; unlike bison, buffalo don't migrate, and tend to stick to broadly the same area through the year, but that's even more true where water or good quality food are in short supply and they can't risk travelling too far. In many places, however, they have to supplement their mineral intake by visiting salt-licks, or even licking one another's sweaty bodies so that as little salt as possible goes to waste. They have even been reported to dig up soil with their horns and eat some of it - although presumably searching for something like iron, rather than salt.

Where the grazing is particularly good, buffalo herds can be hundreds strong, sometimes with over a thousand members. This, and their widespread presence, can be a problem for local cattle herders, since African buffalo can act as reservoirs for foot-and-mouth disease, bovine tuberculosis, and some other diseases that can affect domestic livestock, especially where, for example, the two share the same watering holes. On the other hand, the trampling and disturbance of the soil caused by the passage of such large herds has been reported to improve the quality of the land, encouraging grass and other plants to grow.

As with most bovines, the herds are dominated by the females and their calves. While adult males may join in with the larger herds, they more often split off to form their own small bachelor groups, which stick very closely to known food and water supplies, and barely move about. In fact, they even seem to do this for short periods during the mating season, apparently wanting some time away from the temptation of sexually charged females in which they can actually get some eating done. The females themselves are also surprisingly mobile, and don't always stick with the same herd for long, with a sizeable minority switching between different ones in any given year, likely leading to genetic mixing over time.

During the breeding season - which can last six months or more - males compete with one another for dominance and breeding rights. For the most part, simply lowering their heads and shaking their horns from side to side is enough for a larger male to persuade a younger one to back off. Indeed, while younger males do frequently clash with one another, actual physical conflict between full-grown adults is relatively rare. When it does occur, they charge at one another, smashing those heavy, horn-covered, foreheads together. Whoever can deliver the greatest force of impact wins, and the loser usually turns tail and runs away immediately, typically pursued by the victor.

Pregnancy lasts almost twelve months, which is rather longer than one might expect, even given the size of a buffalo. This is probably to ensure the best timing for the birth, since it has been noted that there is a distinct peak in the number of births about twelve months after particularly good periods of rainfall and plant growth. For cattle in more predictable habitats, this sort of thing may well be less of an issue.

Calves are already around 45 kg (100 lbs) when they are born, but they're unusually helpless for a hoofed animal, taking a few days to really get the hang of standing up and walking around. As one might expect, the mother is particularly aggressive during this time, protecting her calf at all costs; lions, for example, will attempt to eat young buffalo if they can. The calf is generally forced to stop drinking milk at around ten months of age - by which time the mother is likely more than half way through her next pregnancy - and takes several years to reach maturity. Eruption of the animal's teeth is sufficiently slow and predictable that a simple tooth count can be used to age younger buffalo, something that stops working only when they get their full set at six years of age. By that point, females have likely already had a calf or two, but males will have at least another couple of years to wait before getting any serious opportunity.

Much of the research done on African buffalo has been done on the Cape buffalo proper, the subspecies found throughout eastern Africa from the Cape to southern Ethiopia. A second major subspecies, sometimes called the savannah buffalo, lives in the sparse wooded belt south of the Sahara, from Senegal across as far as eastern Ethiopia. The two look rather similar, although the latter are slightly smaller, with straighter horns. Various other proposed subspecies have an even greater resemblance to one or the other of these, but the third undoubted subspecies is visibly quite different.

Forest buffalo
This is the forest buffalo (Syncerus caffer nanus), and it lives in the jungles of central Africa, in Cameroon, the two Congos, Gabon, and Equatorial Guinea. There are even populations on the islands of São Tomé and Príncipe. The word "nanus" means "dwarf", and forest buffalo are much smaller than their kin elsewhere. Even the largest bulls are "only" 130 cm (4'3") at the shoulder, and weigh 350 kg (770 lbs) - large by the standards of most animals, but actually quite small for cattle. While a few have the black coat of other African buffalo, most are reddish brown, and their horns are much smaller, and curved directly upwards, rather than in a downwards-pointing curve. If it weren't for the fact that where they meet up with savannah buffalo in southern Nigeria they frequently interbreed, we might have considered them a different species years ago (and some scientists, as noted above, still do).

While they live in the jungles of the Congo, forest buffalo rely heavily on clearings and open spaces close to rivers, rather than living in the densest parts of the forest. This may be to promote social interactions within the herd, but it may also relate to diet, since while forest buffalo eat far less grass and more shrubbery than other African buffalo, it's still about 45% of what they eat. The herds are much smaller, with about a dozen members being typical, which, again, may be due to the difficulty of keeping in contact in their native environment.

It used to be thought that forest buffalo were the ancestral stock, from which the other two (or more) subspecies had later diverged. More recent genetic evidence, however, shows that the reverse may be true. According to this analysis, African buffalo first appeared around what is now the Central African Republic some time during the mid to late Pleistocene, and split into two populations between 145,000 and 449,000 years ago. One headed east, and then south, to become the Cape subspecies, while the other spread out to the west, becoming the savannah subspecies, and only later headed into the forests, giving rise to the dwarf form.

On the other hand, there is absolutely no doubt that the water buffalo (Bubalus arnee) is a distinct species. Often called "Asian buffalo" by analogy with their African counterparts, wild water buffalo are found in a few isolated patches of land scattered across India and Southeast Asia. Less than 4,000 wild animals remain alive today, but, as so often among the cow-like bovines, the species survives in domesticated form (Bubalus bubalis) with well over 100 million in farmed herds across the world. Indeed, so common are the domestic animals that it's unclear how many of the supposedly wild forms are genuinely so, rather than being feral, or at least hybrids with some domestic ancestry.

Water buffalo are larger than the African species, reaching 1200 kg (1.3 US tons) in the largest bulls, although cows are quite a bit smaller. While they are similar in colour, their horns are very different, stretching out sideways from their skulls with probably the largest spread of any bovid species. The horns are also ribbed, and the keel is so prominent that they're essentially triangular in cross-section. There are a number of subspecies, but here there is less argument than with the African animals, and the visible differences between them, while noticeable if you know what you're looking for, are generally rather slight.

Water buffalo
Domestic water buffalo are very common animals in India and China, were introduced to Europe as far back as the 7th century, and, since the 19th century, have also been bred in North and South America, and in Australia. They are used both as beasts of burden and as a source of milk, the latter being particularly suitable for making cheese, due to a higher fat and protein content than regular dairy milk. There are two broad types of domestic water buffalo, each with a number of different breeds. While they look at least somewhat similar, they have differing numbers of chromosomes and it's quite difficult to get them to interbreed - so far as we know, they don't successfully interbreed with domestic cattle at all, although it is at least possible to fertilise cow ova with buffalo sperm in the laboratory.

Genetic analysis has shown that the two different types of domestic animal diverged from one another well over 28,000 years ago, sufficiently far back that they must have been domesticated separately. The most likely scenario is that the "swamp buffalo" subtype was domesticated in southern China, while "river buffalo" were first domesticated in India. Physically, swamp buffalo look more like the ancestral wild animal, although one test on a wild animal in Nepal showed that it was closer, genetically, to the river type.

As their name implies, left to their own devices, wild water buffalo prefer live in wetlands, including actual swamps and marshes, although they are also found in regularly flooded pastures and forests close to rivers. Apparently having very few sweat glands, they use the water to cool off, and are often seen covered in mud, which not only cools them down but doubtless keeps off biting insects into the bargain. While we don't know their exact dietary mix, they seem to mainly eat grass, supplemented with herbs, shrubs, and bark, and, should they get into a field, they will eat rather a lot of rice or sugar cane.

Herds of water buffalo are small, although, as usual, we can't be sure that this isn't just because they're an endangered species, and couldn't live in really large herds if they wanted to. About ten individuals seems to be normal, with both a dominant female and a single male said to be present. The rest of the herd consists of younger females and their calves, with males off in smaller bachelor groups. What little we know of their breeding habits in the wild suggests they are fairly typical for bovids, and that they share an unusually long gestation period (up to 340 days) with the African buffalo.

As so often with wild cow-like bovines, a large part of the reason that they are endangered is simply that they want to live in the same sorts of places that are ideal for raising domestic cattle. In India and China, in particular, almost all the suitable land is already taken up by agriculture, or by the sprawling cities that it feeds. Hydroelectric dams aren't helping matters, either, not only by creating lakes in prime habitat, but by preventing the kind of seasonal flooding downstream that water buffalo often rely on. While it's a fairly drastic conservation step, we have successfully cloned domestic water buffalo, and shown that, in principle, it's possible to do the same with the wild animal.

One or other, or both, of these two animals are likely to be what most non-Americans think of when they think "buffalo". They are, after all, the two animals known directly by that name, and they're pretty common (albeit only in domestication in one case). But there are, in fact, other animals that can also be loosely described as "buffalo", and it is to these, more obscure, creatures, that I will turn next.

[Photos by "Gouldingken", H. Zell, and Raju Kasambe, from Wikimedia Commons. Cladogram adapted from Bibi 2013 and Stankowich 2009.]

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