Sunday, 28 April 2013

Caprines: Lands of the Ibex

Alpine ibex
The Ice Ages were, on the whole, not a bad time for goats. True, they had to leave the vertiginous cliffs of their mountain homes when they became too cold and barren to support life - and, in many cases, were swathed in vast glaciers. But, as the world grew colder, the vegetation also moved down the mountain slopes, so that, down in the lowlands, goats found plenty of food they had been used to. Indeed, they were better suited to it than most other animals, which had to move to southern climes, rather than merely heading downhill.

Since there are rather more lowland areas than there are mountains, goats could spread much further than they could during warmer times. When the Ice Ages ended, and the hot weather returned, they simply headed back up the mountains. But not, necessarily, the same mountains that they had previously come down from.

As a result, we now have quite a range of goat species across Asia, and, to some extent, Africa. After all, between (and after) the Ice Ages, each population was isolated from those in other ranges, and could develop on its own. Taking, at least for today, our definition of 'goat' to be "any species from the genus Capra", there are probably at least seven, and maybe eight or nine, wild species of goat. The wild goat itself is one, and the markhor, with its bizarre corkscrew horns, is another. Most of the others are collectively known as "ibexes".

(Incidentally, I will use the plural "ibexes" here, because that's the one my dictionary recommends. "Ibex" can also be a self-plural, and, if you really want to sound like you're speaking Latin, instead of English, there's always "ibices").

It's been known for a long time that ibexes represent more than one species. For a long time, though, it was thought that there were just two, one of which, the Alpine ibex (Capra ibex), lived across a wide swathe of Europe and Asia, and even into north Africa. Although there is still some debate about exactly how many species there might be, there seems to be at least a general agreement that the Asian and African animals represent different species to those in Europe. Indeed, one of them, which I'll leave for another day, may not even be an ibex at all, in the strict sense of the term.

Passing over those others for the moment, then, the Alpine ibexes we're left with are the ones actually in the Alps. They haven't always had a good time of it, and, by the 1820s, they had been so extensively hunted that, at best, only a few hundred individuals were left alive, mostly in northern Italy. They weren't just hunted for food, either, although that was a large part of it. Apparently, it was thought that you could make magic charms out of bits of them that would, among other things, protect you from violent death. (It seems to have escaped the attention of the locals that this evidently hadn't worked very well for the ibex concerned, but that's magic for you).

In 1856, Italy created what was later to become the Gran Paradiso National Park largely for the purposes of protecting the ibexes. It worked wonderfully, and, with a general decline in hunting elsewhere, Alpine ibex now number in the tens of thousands. Today, nearly half of them live in Switzerland, with most of the others in Italy, but there are also wild populations in France, Germany, and Austria, and a few have been deliberately introduced to the Slovenian Alps, and, beyond their native mountain range, to Bulgaria. While this history does mean that modern Alpine ibexes have a fairly low genetic diversity, there's no evidence that it's doing them any harm.

In fact, today, life is pretty good if you're an Alpine ibex. This is largely because there's pretty much nothing that eats them living in the Alps. Indeed, while, in harsher areas, they may sometimes run out of food and starve, and some are killed in avalanches, one of their principal causes of death is actually old age - something that's fairly unusual for herbivores.

Alpine ibex are similar in size to wild goats, but with blander coats that vary from chestnut brown in winter to a more yellowish colour in summer. Males have large scimitar-shaped horns up to a metre (3 feet) in length, and 25 cm (10 inches) in girth at the base. Like wild goats, the horns have visible bumps along their length, a new one forming each year as the animal ages. However, the lumps are much larger than in wild goats, and they're even visible in females. However, because the horns of females are much smaller, at no more than 35 cm (14 inches) in length, and therefore grow more slowly, their rings are naturally finer and closer together.

For that matter, males in general are much bigger than females - they can weigh up to twice as much. This is partly because they eat a lot more, in order to bulk up, but also because they continue growing for longer, taking ten years, rather than just five, to reach their full adult size. This larger body mass is most useful for driving away younger suitors from a buck's preferred mate, but it's how many calories the male has been able to divert into growing his horns that really matter: the bigger the horns, the better a catch the male is.  For that matter, a male with larger growth rings on his horns is also likely fitter than one without, since it means that he's still been able to grow his horns rapidly even as he ages.

Alpine ibexes spend most of their lives above the tree-line, typically between 1600 and 3200 metres (5,250 to 10,500 feet) in altitude. They'll occasionally wander down into lower woodlands, especially in winter, but alpine meadows seem to be their preferred habitat, especially on steep south-facing slopes with gradients between 30 and 45°. As you might expect, given that habitat, they largely eat grasses and low-lying herbs, only rarely tackling things like bushes, simply because there aren't any around. They're not very keen on warm temperatures, and will head uphill if the weather is hot, hoping that it's colder higher up the mountain.

Although males stay with their mothers for the first two or three years, they otherwise live in single-sex herds outside the mating season, each gender establishing a clear hierarchy of dominance among themselves. This sort of thing proves particularly important during the midwinter rut, when larger, more dominant males get to do around 85% of the mating. They manage this by standing guard over a single female that they fancy, whacking any young upstart who tries it on with her - although, to be fair, once they're sure she's pregnant, they may well go and look for somebody else.

Of course, the converse of that is that 15% of the time, it's evidently not working. The tactic here is for young males to dash in when the guardian isn't looking, chasing the female away from him to get her on her own for a while. It's something of a risk if they get caught, but evidently worth the trouble (after all, it only has to work once, while the older male is spending a lot of his time standing about looking tough).

Pregnancy lasts 165 to 175 days, about two weeks longer than in wild goats, and twins are much rarer. Both sexes are ready to mate at two to three years of age, although it can take around nine years before a male is large enough to try the more successful 'guarding' tactic. They live for up to sixteen years in the wild, and frequently do, which is pretty good going when you consider that most other herbivores of their size would have been eaten long before then.

Iberian ibex
Back when many scientists thought that all the Asian and African ibexes were just examples of the Alpine kind, the one that almost everyone agreed wasn't was the Iberian ibex (Capra pyrenaica). This is ironic, since it turns out that of all the ibexes, they're the most closely related - if there is only one that could be the same species as the Alpine, this is it. Evidently, they're descended from a single European stock that retreated into different mountain ranges when the Ice Ages ended.

Having said that, Iberian ibexes are less insistent on mountains than their Alpine kin. During the heat of the summer, many retreat to 2,300 metres (7,500 feet) or so, but a great many more live in places where that just isn't an option, and stay in the lowlands year round. Indeed, the one place you might reasonably expect to find them - the Pyrenees - doesn't have any, and they're most common in eastern regions, close to the Mediterranean coast.

It wasn't always so, and the first Iberian ibexes to be scientifically described did live in the Pyrenees. That subspecies, however, became extinct as recently as January 2000, when the last known individual died. In an unusual, if depressing, footnote, Pyrenean ibexes became the first animals ever to become extinct twice, when a cloned individual was born alive in 2009, resurrecting the subspecies... for the nine minutes it took her to die from defects in her lungs.

Two subspecies still remain, and they're actually doing fairly well (although one not so well as the other), in scattered populations across Spain. They have even been re-introduced to northern Portugal, where a fourth subspecies once lived, before being hunted to extinction in the nineteenth century.

Perhaps one reason that the Alpine and Iberian ibexes were thought to be distinct species, even when the others weren't, is that they do look rather different. Iberian ibexes have black markings on the chest, flanks, and forehead, which are particularly obvious in males, and during the summer, when the rest of the coat is at its palest. More significantly, perhaps, their horns are a different shape, being smoother, and with an upward twist at the end in most adult males.

Living at lower altitudes, Iberian ibexes tend to eat more leaves, and less grass, than their Alpine kin, although it does depend where in Spain they happen to live - it isn't a heavily forest country. On the other hand, they don't like too much heat, either, and tend to take a long siesta in the afternoon, feeding and moving about at cooler times of the day. During the hottest parts of the year, they will even take to feeding on moonlit nights, sheltering under cover during most of the hours of sunlight. Although both sexes like to stay close to rocky terrain, females are more eager to keep to open country where they can see predators coming - unlike the Alps, there are still wolves in Spain.

Pregnancy lasts a little longer than in Alpine ibexes, so, in order to time births for the same time of year, the rut takes place slightly earlier, between November and December. Males stop growing their horns during the mating season, presumably because they're saving all their energy for other activities. With more predators to worry about, not to mention a recent widespread epidemic of mange, they get less opportunity to live to a ripe old age, although a few have managed up to fifteen years.

Nubian ibex
The Nubian ibex (Capra nubiana) lives along the Red Sea coasts of Egypt and Sudan, and also in Israel, Jordan, and southern and western parts of the Arabian Peninsula. With one population on the shores of the Dead Sea, it has the unusual distinction of being the only wild species of goat to habitually live below sea level. Still, even if much of their home isn't especially mountainous, it is very rocky, and exactly the sort of marginal terrain in which goats excel.

Naturally, it's also somewhere where a good tolerance for heat is absolutely required, although even Nubian ibexes avoid the worst of the sun by sticking to north-facing slopes for much of the summer. Although they'll eat pretty much whatever plants they come across, where they live, there isn't exactly a lot of choice, and their diet isn't particularly varied. They mainly eat leaves, seed pods, and acacia twigs  during the dry season, but are able to switch to grasses and herbs when the rains come, giving the bushes time to regrow for the following year.

Physically, they much resemble Alpine ibexes, although they're paler, with a coat that may provide better camouflage in their dusty homeland. They breed earlier in the year than other ibexes, presumably to time births for the most fertile season, and live in small herds of less than ten individuals. One study shows that dominant females are not only more aggressive than their younger sisters, but are also more likely to have male offspring. Their life is much tougher than that of their kin in Europe, as a combination of the arid environment, where rains may fail and kids often die young, and of the presence of both wolves and leopards. The presence of humans, and, in particular, encroaching agriculture, also serves to make their life less secure.

Walia ibex (female)
Life is much harder, however, for the Walia ibex (Capra walie), officially considered an endangered species. Sometimes thought to be only a subspecies of Nubian ibex, Walia ibex are found only in the Simien Mountains of Ethiopia, an environment completely different from that of their close relatives. Here, where they live at elevations between 2500 and 4200 metres (8,200 to 13,800 feet), there are rich forests and moist savannahs occupying dramatic slopes and steep canyons. Due to the lack of studies, we don't exactly know what they're eating there, but it's a fair bet it isn't dry seed pods and thorny desert scrub.

There are other differences, too: they apparently breed in the spring, not the late autumn, and they have a rich chestnut coat with clear black markings on the face and chest. Unusually, males and females stay together throughout the year, although that may be because the current population is so small. There may be as few as five hundred individuals left, although, since there were only half that in the mid 1990s, it's at least moving in the right direction.

Heading back to Asia, and across the Middle Eastern home of the 'true' wild goats, we come to another mountain range: the Caucasus. The goats here could plausibly be (and sometimes are) called "ibexes", but it's more common to use the local name, "turs". Considering that the Caucasus Mountains aren't an exceptionally long range, as mountains go, it's perhaps surprising that there are different species of tur at either end of them.

These are the Kuban tur (Capra caucasica) in the west, and the Dagestani tur (Capra cylindicornis) in the east. Although usually considered distinct species, this isn't uncontroversial. This is largely because there's some evidence that they regularly interbreed in those parts of the mountains where they meet up, although, so far as I know, no definite hybrid population has yet been found.

Kuban tur
The two do look somewhat different, although that's not really proof of anything. Perhaps the main difference is the shape of the horns, which are relatively smooth, and curl outwards and around in an arc in the Dagestani tur, and look more ibex-like in the Kuban species. Both are a relatively uniform brown colour, becoming paler and brighter in summer, with only a few dark markings on the legs and tail.

They live exclusively in the mountains, never venturing below 1000 metres (3300 feet) in elevation, and then only on steep slopes (the steeper, the better, within reason) and along precipitous cliffs. Much of the area is forested, with the turs showing a preference for pine forests over others, although much of their diet consists of grass and undergrowth. Both species are also found above the treeline, with the Dagestani species having been reported as high as 4000 metres (13000 feet), and the Kuban slightly less.

Already preyed on by the local wolves, Dagestani turs struggle with hunting and with encroaching livestock farms. Doubtless the fact that many of them live in Chechnya , where wildlife conservation isn't currently a top priority, doesn't help. The Kuban tur, however, is much worse off. They inhabit a narrow strip of land along the Georgian-Russian border, 250 km (155 miles) in length, and, at most, only 70 km (45 miles) across. That's an even smaller area than the Walia ibex. True, there's a lot more of them - perhaps five to six thousand - but, unlike the Ethiopian species, their population is declining. In fact, it's probably halved in the last twenty years, so there's a sound reason that this, too, is considered an endangered species.

[Pictures by Nino Barbieri, José M. Gómez, "Little Savage", Paulo Philippidis, and "Pavanravela", from Wikimedia Commons. All pictures of males, unless otherwise indicated.]

1 comment:

  1. Bucardo Ibex cloning efforts resume: