Showing posts with label antelopes. Show all posts
Showing posts with label antelopes. Show all posts

Saturday, 30 November 2024

Antelopine Antelopes: Antelopes with Trunks

During the 20th century, when we were trying to group animals together into some kind of evolutionary tree, we often found that there were some that were sufficiently strange that they didn't quite fit. This could be at the level of families (e.g. the red panda) or even higher groupings (aardvarks), but often it was apparent what general kind of animal something was, just not exactly where it fit. Such was the case with the saiga (Saiga tatarica). 

Saigas once lived across the steppes of central Asia, in lands stretching from Moldova to China. Hunting, for both meat and horns, caused a dramatic decline in their numbers throughout the 20th century, accelerating after the collapse of the Soviet Union and leaving them virtually extinct by the dawn of the 21st. A mass outbreak of infectious haemorrhagic septicaemia in 2015 threatened to finish the job, but since then there has been a truly remarkable recovery, with what's thought to be an eleven-fold increase in their numbers between 2015 and 2022. This is so great, in fact, that the species was removed from the international endangered species list in April 2023.

Sunday, 3 November 2024

Antilopine Antelopes: Dik-diks

Kirk's dik-dik
The "antilopine" antelopes are, as their name might suggest, mostly typical examples of their kind. I suspect that when many people think of antelopes in general, gazelles and springbok are among the first to come to mind (although, to be fair, so might say, impalas). Traditionally, the antilopines have been divided into two main groups: the gazelle-like antelopes and the dwarf antelopes, with the latter surely being the less familiar to those of us living outside of Africa. Both groups have at least some species that don't fit the "typical" image of the subfamily. For the gazelle-like animals, that's probably the gerenuk and its relative, the dibatag.

Among the dwarf antelopes, we have the dik-diks.

While some researchers subdivide them further, four species of dik-dik are widely recognised, at least three of which are reasonably common within their respective homelands. This may partly be because they are too small to be worth hunting for meat - although, inevitably. this still happens from time to time. 

Sunday, 6 October 2024

Antilopine Antelopes: Dwarf Antelopes of Eastern and Central Africa

Oribi
The term "dwarf antelope" can reasonably be applied to many different kinds of antelope that are smaller than, say a typical goat. In this common sense, it's not a precise term, and could refer to species that belong to quite different branches of the antelope family tree. When mammalian zoologists used the term in the 20th century, however, it was often more precise, referring to those thought to be most closely related to the gazelles as a branch within the "antilopine" subfamily of "typical" antelopes.

Technically, these dwarf antelopes were collectively referred to as "neotragines" and assumed to be a natural grouping within the antelopes more widely. Genetic analysis over the last couple of decades has muddied these waters considerably, not least because the genus for which the branch was named, Neotragus, turns out not to be closely related to the gazelles, and is something else entirely. Even if we look solely at those dwarf antelopes that we can still say belong to the antilopine subfamily, it turns out that they don't have a single common ancestor. Specifically, one of them is more closely related to gazelles than it is to any of the other members of its purported evolutionary branch. 

Sunday, 8 September 2024

Antilopine Antelopes: Dwarf Antelopes of southern Africa

Steenbok
The "antilopine" subfamily of antelopes, so named because it happens to include the first animal scientifically described as an antelope rather than a goat, is itself divided into at least two major branches. There may or may not also be minor ones, depending on what you think is worthy of naming, but the two main ones are quite clear, and perhaps separated from one another around 12 million years ago towards the end of the Middle Miocene.

One of these groups contains the gazelles, along with the springbok, some other gazelle-like animals, and that "first" antelope mentioned above, the blackbuck. These are, for the most part, smallish slender, fast-running antelopes living in arid or semi-arid habitats in both Africa and Asia. The second group are the dwarf antelopes, found only in Africa and quite visibly different from gazelles. 

Sunday, 11 August 2024

Antilopine Antelopes: Almost-Gazelles of Tibet

Tibetan gazelle
It's often the case that the common name of a type of animal in English does not map directly to a scientific understanding, especially once we add modern genetic discoveries into the mix. So it is with the word "gazelle", which derives from an Arabic word that literally means something like "graceful" or "slender" and is used to refer to a range of relatively slim, fast-running antelopes. 

In a stricter, scientific sense, gazelles would really only include those species closely related to the genus Gazella, short-coated animals, often with dark stripes down the side, and that tend to live in hot deserts or semidesert regions. Even this excludes animals such as springboks, since they are less related to the true gazelles than is, say, the blackbuck. Most true gazelles live in Africa, but there are some in Asia, mostly in the Middle East, but with one reaching as far east as northern China. However, a second group of animals commonly called "gazelles" also lives in Asia, and not somewhere that most Westerners would generally associate with such animals.

Sunday, 14 July 2024

Antilopine Antelopes: The Giraffe-Gazelles

Gerenuk
Despite appearances, true gazelles are not the closest living relatives of the springbok. That honour is probably tied between two other species, although there have yet to be sufficient genetic studies to absolutely nail that down - one could be closer than the other. They likely diverged from the springbok over 10 million years ago in the late Miocene, earlier than the blackbuck is thought to have diverged from the true gazelles, so it's perhaps unsurprising that they look quite different.

They also look slightly odd, and very distinctive.

The better-known of the two is the gerenuk (Litocranius walleri). The name comes from the Somali word for the animal, but it is more commonly known as the "giraffe-gazelle" in many European languages, and it's easy to see why. It is, of course, much smaller than a giraffe, with males having a shoulder height of around 100 cm (39 inches). The colour is also different, a relatively uniform reddish-brown over the back, with a paler shade in the flanks, neck, and limbs, and stark white underparts. There are also white markings on the face, around the eyes. Only the male has horns, which rise almost vertically out of the skull before curving back in an S-shape.

Sunday, 16 June 2024

Antilopine Antelopes: Blackbuck and Springbok

Blackbuck
The gazelle-like body form has evolved at least three times within the "antilopine" subfamily, and arguably a few more times among antelopes more generally. A fast-running animal, able to outpace many of its predators, is clearly a useful thing to be if you're a herbivore. Only one of these three evolutionary events led to what zoologists would describe as the "true gazelles", although at least one of the others resulted in an animal so strikingly similar to gazelles that it's surprising that molecular evidence tells us it doesn't have an immediate common ancestor.

The blackbuck (Antilope cervicapra), however, does not look much like a gazelle. It is one of the five currently recognised species of antelope whose scientific name dates back to the origins of modern taxonomy in 1758. In 1766, Peter Simon Pallas first distinguished antelopes from goats, creating the genus Antilope to incorporate no fewer than seventeen species - including the Dorcas gazelle, which would later go on to become the defining species of the Gazella genus when that was created in 1816. While every other living species was eventually split off elsewhere, the blackbuck remained, and its genus gives its name to the entire subfamily. (The second part of the name, incidentally, translates as "deer-goat" and remains the name of the animal in French).

Saturday, 27 January 2024

No Such Thing as an Antelope

There is no such thing as an antelope.

Or at least that's true in the same sense that there's "no such thing as a fish". Which is to say that, obviously, antelopes exist but they aren't a scientifically definable group of animals. Or that, if they were, that group wouldn't map closely to what the regular English word "antelope" is supposed to mean.

The word entered English during the Rennaissance, and descends, via Latin, from the Greek "ανθολοψ". That first appears in the 4th century (so not old enough to be Ancient Greek, as such) and referred at the time to a mythical beast said to live along the Euphrates that had horns so sharp and serrated that it used them to cut down trees. We don't know why the Byzantine Greeks called it this, but there's not some "lope" that it's "ante" to (nor, to use most other European languages, is it an anti-lope); it's just a coincidence that the word sounds that way. For all we know, they were borrowing a word from some other, older language spoken somewhere out east.

Sunday, 20 November 2022

The Importance of Blue Bullshit

Monkeys and apes in general, and humans in particular, have a relatively poor sense of smell but the same is far from true of most other mammal species. For such animals, scent can be an important method of communication and this is often done through scent-marking, leaving long-term messages that can be understood by other passing members of your species.

A common way to do this is by rubbing specially adapted scent glands onto objects - these glands are often on the feet or the sides of face, which is why many animals will rub their heads against things to mark their territory. An alternative is to either urinate or defecate in a particular location, the natural aroma of the excreta often being aided by anal scent glands. We are all familiar with a dog's need to mark its territory in this way and it's hardly alone in this respect.

This can provide all sorts of useful information to other animals from the same species, such as territorial ownership, social dominance, willingness to mate, and so forth. When the method used to deposit this information is defecation rather than urinating, the result is termed a latrine or midden - which, in the biological sense, are basically alternative words for "dungheap". Animals that use this method of scent-marking include rhinoceroses, lemurs, and antelopes. (And we can but wonder what human cities would be like had we evolved from a species that communicated in this way).

Saturday, 28 November 2020

Miocene (Pt 23): Giraffes Become Tall, Hippos Stay Dry, and Antelopes... Get Eaten

Palaeotragus, a short-necked giraffe
About half-way through the Late Miocene, around 8 million years ago, worldwide temperatures began to drop significantly, and even tropical Africa did not escape the effects. In its case, this didn't lead to cold and barren steppelands, and, indeed, the world may still have been slightly warmer than it is today, but there is evidence of the expansion of grasses across many parts of the continent. Perhaps enhanced by the closure of the Mediterranean Sea during the Messinian Salinity Crisis and disruption of the monsoons, North Africa also became much drier than before, although whether the Sahara as we know it today dates back quite that far remains controversial; there is some evidence of sand dunes that far back, but also of numerous rivers crossing the region.

These changes in climate also affected the animal life on the continent, to the benefit of some and the detriment of others. Pigs are omnivorous animals, and one might expect them to have survived such changes relatively unscathed. In a sense, this is true, since they remained common on the continent, but the nature of particular species living there did change.

Sunday, 15 September 2019

Unravelling the Bushbuck

Imbabala
Three years ago, I wrote a series of posts on the various species of bovine. This was using 'bovine' in the wider, technical, sense than it's everyday meaning, essentially including all animals more closely related to cows than to sheep or goats. This obviously includes all the really close relatives of cattle - bison, buffalo, yak, and so on - but it also includes a number of animals that are more accurately described as 'antelopes'.

Most species of these 'bovine antelopes' belong to the genus Tragelaphus, collectively known as 'spiral-horned antelopes'. Especially if we include the large cow-like elands (sometimes given their own genus, Taurotragus) these are a fairly diverse range of animals, including some adapted to open woodland or savannah, and others adapted to dry scrub, mountain slopes, dense jungle, or swampland. Perhaps because it seems to be the most adaptable of the species, the most widespread of the spiral-horned antelopes is the bushbuck (Tragelaphus scriptus).

Saturday, 17 March 2018

Miocene (Pt 6): The Coming of the Mice

Palaeotragus
The Early and Mid parts of the Miocene epoch were, for the most part, times when the world was much warmer than it is today. It wasn't a steady pattern, however, and I've already described how the fluctuations in climate, over the course of many millions of years, affected the rodents of Europe. It was a time when the most common small mammals in Europe were not mice and voles, but dormice, accompanied by early hamsters, squirrels, and the gliding eomyids.

By 10 million years ago, however, the colder, drier climate had become locked in for the long term. We know that the forests of Europe changed dramatically at this time, the old subtropical trees, such as figs and palms, being replaced by oak, alder, and elm. Likely as a result of this change in the available food supply, most of the dormice died out, leaving only a few close relatives of the relatively small number of species we have today.

Sunday, 30 July 2017

Miocene (Pt 2): Before There Were Mice

Heteroprox
After a brief cold snap at the very dawn of the epoch, the world of the Miocene warmed rapidly. Europe became, if not truly tropical, at least subtropical, with the interior covered by great forests of oak, laurel, and cinnamon, with magnolia and figs joining pine trees in the highlands. Along the coasts, the hot, damp, climate encouraged the growth of mangrove swamps and palm trees as warm sea currents flowed in from the Indian Ocean - still connected to the Mediterranean at this time. With no ice caps at the North Pole, and relatively few at the South, sea levels were much higher, and parts of continental Europe may, in those days, have still been islands. Certainly, Aqutaine in south-western France and the lower Rhône valley in the south-east were shallow bays stretching some way inland, as was what is now the Tagus valley in Spain and Portugal.

This rich and verdant landscape was home to a wide range of animals, many of them survivors of even earlier times. Many of these, such as the tapirs, didn't survive long in Europe, but a great many did, with musk deer, pigs, and rhinos dominating the herbivorous fauna, and animals less familiar to modern eyes taking the lead among the large carnivores.

But then, as now, the great majority of mammal species were small. While the sight of Diaceratherium rhinos wallowing in the lush swamps of the Swiss shoreline is the sort of thing that would draw the immediate attention of a time-travelling tourist, there was also plenty going on underfoot. Yet the two most common groups of small non-flying mammals that we have in Europe today - the mice and the voles - did not yet exist. So what was there?

Sunday, 6 November 2016

Bovines: Bushbuck and More

Bushbuck
Of all the many kinds of antelope found in Africa, the one that is most widespread is the bushbuck (Tragelaphus scriptus). Bushbuck are essentially found throughout the whole of sub-Saharan Africa outside of the densest parts of the Congo jungles, the Kalahari Desert, and the drier parts of the veldt and the Horn of Africa. That's a huge range; everywhere from Senegal to Angola, and from Djibouti to the Cape.

Bushbuck are the smallest of the African bovines, sufficiently so that any resemblance to cows beyond the basics true of all antelopes (horns, cloven hooves, and so on) is quite absent. Specifically, they stand 60 to 100 cm (2' to 3'3") tall at the shoulder, with the males slightly taller, and much more heavily built, than the females. They do, however, much more closely resemble their larger immediate kin, such as bongos, having a somewhat similar coat colour, and the same twisted horns that make about a single turn along their length. Unlike in bongos, however, the horns are only found in the males - a feature shared with another close relative, the swamp-dwelling sitatunga.

Sunday, 9 October 2016

Bovines: Bongos in the Jungle

Bongo
Broadly speaking, the more cow-like bovine species tend to be found wild in forested habitats, often with quite dense foliage. In contrast, the antelope-like bovines tend to prefer more open wooded country or scrubland. But these are both very crude generalisations. Plains bison and yak, for example, both live in open terrain, and, on the other side of the coin, there are bovine antelopes that prefer forest to savannah.

Among these is the bongo (Tragelaphus eurycerus), which can be found in three, entirely separate, regions of equatorial Africa. The two main populations live along the southern coast of West Africa, from Guinea to Benin, and across the heart of the Congo Basin and surrounding jungles, from Cameroon and Gabon in the west almost to the Ugandan border in the east. The vast majority of bongos live in these two areas, which are nonetheless separated by over 1,000 km (620 miles) of intervening land (much of which is Nigeria). The third population is found only in a couple of tiny mountain refuges in Kenya, where they cling to the forested slopes, migrating up and down them each year as the weather changes.

Sunday, 11 September 2016

Bovines: Spiral-Horned Kudu

Greater kudu (male)
Most "bovine antelopes" - those more closely related to cows than, say, sheep - are collectively referred to as "spiral-horned antelopes", because of the shape of their horns. In many species, the horn makes a single 360° turn once it is fully grown, but others have several twists to the spiral. In elands, the twist is tight, marked clearly by a ridge that runs along one edge, but in no species is the spiral perhaps more evident than in the two species of kudu, where the horns are relatively narrow, with a loose, open curve.

The more widespread and common of the two species is the greater kudu (Tragelaphus strepsiceros). These are particularly large antelopes, with the males standing up to 157 cm (5' 2") in height at the shoulder, and weighing up to around 270 kg (600 lbs). Indeed, they are the second tallest species of antelope, after their relatives, the elands. Females are quite a bit smaller, at around two-thirds of the weight, and standing no more than 132 cm (4' 3"). As with most other spiral-horned antelopes, the coat is a brownish colour, with narrow vertical white stripes on the flanks.

The horns, are, however, their most distinctive feature - the second half of their scientific name means "twisted horn". These are typically about 100cm (3' 3") long in fully grown males, and would be even longer were you to measure them along the curve, rather than in a straight line from the base to the tips. Although the occasional horned female has been reported, this seems to be a rare aberration. Even in males, the horns grow slowly enough that it is possible to age younger individuals by how well they've developed; it takes two years to complete the first full turn, and the final adult form, with two to two-and-a-half turns, is reached by around four and a half years.

Sunday, 7 August 2016

Bovines: The Largest Living Antelopes

Common eland (male)
Over the last few months I have looked at the various species of cow-like bovine, including such creatures as yak, bison, and water buffalo. But we've known, since at least the 1950s, that there are also a number of other animals that are more closely related to cattle than they are to other kinds of bovid. Although the choice of terminology is ultimately arbitrary, these are commonly considered to be members of the subfamily Bovinae, and thus can also be described as "bovines".

They are not, however, physically very cow-like, and so are instead described by the more generic term "antelope" - which really just means "any bovid that's not obviously some kind of cow, sheep, or goat". The great majority of antelopes are therefore not "bovines" in any sense, belonging to their own distinct subfamilies. The majority of those that are are commonly referred to as spiral-horned antelopes. While all bovines are said to have some degree of spiral growth pattern to their horns, it's only in these antelopes that it's really obvious, with multiple turns of the spiral clearly visible to the observer.

Sunday, 12 June 2016

Pliocene (Pt 11): A Profusion of Pigs

Probably the most numerous large mammals in Africa today are the antelopes, of which there are a great many species. In this respect, the Pliocene was not much different, with antelopes providing a large part of the diet of the various carnivores that lived before the Ice Ages, from lions and hyenas to sabretooth cats. However, the mix of antelope species was different then that it is now, not least because of the generally lusher environment that existed in Africa during the earlier part of the epoch.

Even so, most of the antelopes of the day were related to species that we would recognise today. For example, even at the very beginning of the epoch, around 5 million years ago, South Africa boasted a gazelle similar in size to a modern springbok. Indeed, springboks proper appeared around 3 million years ago in the same general locality, where they were represented by at least two extinct species until one of them (probably Antidorcas recki) evolved into the iconic modern animal.

The gazelles of the early Pliocene were likely different in their habits from the modern sort, being more adapted to woodland than open plains, but, moreover, they were not as common, comparatively speaking, as they are now. Instead, it appears that, at least in East Africa, a group known as the spiral-horned antelopes (about which I will have a lot to say elsewhere on this blog over the coming months) were rather more numerous.

Sunday, 7 December 2014

Struggle of the Marsh Antelopes

Puku
All things being equal, herbivores would prefer to live in those areas with the best and most lush vegetation. The reality, of course, is that all things are very rarely equal. There are all sorts of reasons why a herbivore might not wish to live somewhere where they can get the best quality food.

One of those reasons is the presence of predators. If predators also live where the vegetation happens to be best, a herbivore has to strike a balance between the quality of the food and the risk of getting eaten. But a herbivore also has to worry about... other herbivores.

If you eat exactly the same thing as some other animal, and try to do so in the same place, whichever one of you is even marginally better at it is going to, over a sufficiently long period of time, out-compete the other one and drive it to at least local extinction. We see this, for example, in England, where grey squirrels introduced from North America have out-competed the red squirrels native to the island. There are only a few places left in England where you can still see red squirrels, but the foreign grey squirrels are quite common.

Sunday, 13 April 2014

Pleistocene (Pt 14): Ice Age Africa

Giant warthog
In the earlier parts of this series, when I described the animals of Ice Age Europe, I said that the continent, at that time, had a feel reminiscent of present-day Africa. But, if that's so, what was Africa like during the Ice Ages?

The answer is, perhaps disappointingly, "not that different to how it is now". Indeed, of all the settled continents, it's probably Africa that has changed the least since the Ice Ages. You might think that this has something to do with Africa being close to the equator; in particular, that it's too close for whopping great sheets of ice to have rolled across the countryside.

Which they didn't, so that much is true. Indeed, the southern hemisphere in general had far less ice cover than Europe, Asia, and North America. That's due mainly to the way that the continents happen to be arranged, with glacial ice sheets only being able to get as far as southern South America (there are fjords in places like Tierra del Fuego). Presumably, sea ice extended much further across the Southern Ocean than it does now, but that would have little effect on land-based animals.

But that's not to say that Africa, or Australia, were unaffected by the Ice Ages. Africa was colder than it is today, and, to begin with at least, rather drier, too. The Sahara and Kalahari deserts were more extensive than they are today, with the semi-desert belt of the Sahel being quite a way south of its present position, running through what are now fairly lush countries such as Guinea, Nigeria, and northern Kenya.