Sunday 7 November 2021

All the World's Deer: The Largest Deer and Other Oddities

It will probably come as no surprise that the largest species of deer alive today is the moose (Alces alces), confusingly known as the "elk" in some parts of Europe. The latter is, of course, the original English name for the animal, and remains, more or less, the name for it in languages such as German and Swedish today. The word "moose" comes from one or more of the Algonquian languages and entered English no later than the 17th century, although why Europeans chose to rename the animal they already knew about rather than come up with a new name for the novel American beast that looked like a red deer is unclear.

At any rate, moose are undeniably large, considerably larger than the American elk. They typically stand around 200 cm (6' 6") at the shoulder, with females not much shorter than males. The males are, however, significantly bulkier and more muscular, with a full-grown bull typically weighing between 300 and 600 kg (660 to 1300 lbs) and females around 25% less. The occasional exceptional individual can, of course, be much larger than this but, even ignoring those, that's pretty big for a deer.

Even were it not for their large size, moose would be among the most distinctive of all deer species. They have long limbs and a short neck, with a noticeable shoulder hump, a long dewlap, and an elongated head with an almost pendulous nose. Unlike most other deer, the young are not born with spots. They belong to the capreoline branch of the deer family and, like most other members of that subfamily, have no brow tine on their antlers. Instead, the antler splits in two, with a forward branch that may be analogous to the trez on other deer, and a main beam behind it. Both branches flatten out into a "palmated" sheet from which multiple tines project out in (more or less) a line. The exact shape varies, with the moose subspecies from Mongolia and northern China having little of any of the palmation/flattening.

Most capreoline species of deer living today do so exclusively in the Americas. This, however, is not where moose originated. The last common ancestor of all living moose lived somewhere in Siberia, roughly between 150 and 50 thousand years ago. From there, they had little difficulty migrating west to Europe, but they didn't enter America until less than 15,000 years ago - probably at around the same time as humans and American elk did. That original founder population seems to have spread rapidly through the new continent, likely with a small number of long-distance migrations, rather than multiple short distance hops.

Today, moose are found in northern forests on both sides of the Atlantic, from Scandinavia eastward to the Bering Sea, and from Alaska to Newfoundland, as well as in the western US as far south as Utah. Traditionally, there are said to be eight living subspecies - one in Europe, three in Asia, and four in North America - although this is necessarily subjective. They also lived in the Caucasus region until the 19th century, and this population may or may not represent a now-vanished ninth subspecies.

Moose are forest-dwelling animals, although they sometimes travel into more barren habitats, especially in Alaska. It is generally said that moose dislike places where the summer temperature regularly exceeds 14°C (57°F) although there may be some exceptions to this and they can cope with higher temperatures in zoos before suffering physiological heat stress. At the opposite end of the scale, winter snows have to regularly reach over 70cm (28 inches) before they'll be deterred and seek to move elsewhere.

In the forests, they browse on the younger and more tender parts of trees and bushes. Rowan and willow seem to be particular favourites, followed by birch and aspen, although this seems to vary with the exact mix of trees where they live, with, for example, some taking the trouble to seek out pine and others avoiding it. While they are not quite as solitary as some of the smaller deer species, they are much less so than most medium-sized species, with females living in small family groups, and males largely solitary once they reach adulthood. Some moose migrate for considerable distances each year, but some don't migrate at all, or just for short distances to reach preferred winter feeding grounds; relative snow quality in different regions may be one reason for the difference in habits.

The rut takes place in the autumn, with each bull moose tending and guarding a single female until she mates with him, and then wandering off in search of another. The sort of harem-building seen in more gregarious deer species is rarely seen, but not entirely unheard of. The bull does, however, go through all the usual acting up that stags of other species are inclined to, thrashing vegetation, dribbling and urinating everywhere, and fighting off any smaller males (less than five years old, as a rule) that dare to try anything. Where hunting by humans isn't a major concern, female moose live past their reproductive peak (something not especially common in wild animals), being less likely to give birth to twins past the age of twelve, but investing more effort in raising those calves they do produce. Even in the wild, moose can live for sixteen years.

Tufted deer
(the antlers are just visible...)

While the moose is the largest living deer, the smallest is the northern pudu. This is not, however, the deer with the smallest antlers; that honour instead goes to the tufted deer (Elaphodus cephalophus) of China. Although closely related to muntjacs, they are nonetheless distinct enough to be given their own genus and, among other things, have an extra pair of chromosomes. 

They are similar in size to some of the larger muntjacs, standing about 60 cm (2 feet) high at the shoulders, and with a bland, dark coat. Unlike muntjacs, they lack scent glands on their foreheads but do have some on their lower legs. Most obviously, however, their antlers are much smaller, just tiny bumps on the head that are almost completely hidden behind the large tuft of hair that gives the deer their name. They are just grown once, remaining throughout life rather than being replaced each year. Their canine fangs are even larger than those of muntjacs, and almost as large in females as in males.

Tufted deer live further north than muntjacs, living only in China, and possibly just across the border into Myanmar. Here, they live in cool broad-leaf forests at up to 4,750 metres (15,500 feet) elevation, feeding on bamboo, hawthorn, and fruit such as sarsaparilla and bilberries. At least some of them may migrate downslope in winter to avoid the coldest weather. They are most active around dawn and dusk and, like muntjacs, are mostly solitary, letting out a "barking" sound when suddenly alarmed.

One of the few times they are seen in groups is when males compete with one another during the autumn mating season. According to the few observations that have been made, they seem to do this mainly by head-butting, although it seems hard to imagine that those long fang-like tusks aren't used for something. The single young is born with one or two rows of spots along the back, but can hardly be said to be speckled as most deer fawns are.

Back when I started this series I mentioned that there is one species of living deer that was, for most of the 20th century, regarded as so strange that it was placed in neither the cervine nor capreoline subfamilies. We now know that it is actually a capreoline deer, but it's easy to see why, in the days before modern genetic analysis, we thought otherwise.

Water deer

This is the water deer (Hydropotes inermis), a threatened species found natively only in central-eastern China and western Korea, although significant populations now live in England and France after escapes from zoos and parks. It's only slightly smaller than the tufted deer, with a shoulder height of 55 cm (1' 10"), although, unusually among deer, the females are heavier than the males. They have the usual set of scent glands on the face, feet, and groin and, in many other respects, don't look so odd for deer of their size.

Except for one thing: they don't have antlers.

Not even the stubs of the tufted deer. No antlers at all. And this was why they were placed in their own subfamily, since they must surely be a fossil relic, a descendant of early deer, before they had ever developed antlers, and therefore, logically, from before the two living subfamilies of deer diverged from one another. Well, no, because as the genetic data now tells us, they are descended from deer that did have antlers and then lost them in the course of their own evolution. But, granted, that seems a surprising thing for a deer to do.

What male water deer do have, like muntjacs and tufted deer, are large sabre-like canines. The females do have canine teeth as well, but these are much smaller, and not visible when the mouth is closed. This makes them look somewhat like musk deer. Indeed, while initially described as a "true" deer by Robert Swinhoe in 1870, it was moved to join the musk deer in 1872. Even before that decade was out, however, other researchers pointed out that both the skeleton and soft tissue anatomy matched antlered deer and not those of musk deer. 

We now know that they are surprisingly closely related to roe deer although we don't have any fossils that tell us when and how they lost their antlers. For that matter, it turns out that musk deer are actually more closely related to antelopes than they are to true deer and that any resemblances are coincidental, perhaps the result of a similar lifestyle.

Water deer, as their name suggests, tend to live close to water, although they aren't true swamp-dwellers like barasingha or marsh deer, instead preferring heavily-vegetated areas around forest edges. At least in their native habitat, they feed on a mix of woody plants and herbs, with relatively little grass.

They seem to be about as antisocial as deer get, living alone and paying little attention to others of their kind, although they may occasionally gather together for convenience in places where food is plentiful. The usual benefits of safety in numbers don't seem to apply; unlike most deer, water deer do not flash their tail as they flee in order to warn others of danger and, indeed, the underside of the tail is not the bright white so often seen in other species. 

When they do meet up during the autumn rut, males compete with one another by slowly escalating their aggression until one backs off, but they don't seem to butt heads. If the usual threats fail to work then they kick one another with their front legs rather than head-butting, and only move on to biting as a last resort - given the size of their canines, this can be lethal when it does happen. 

Water deer are able to colonise new areas of land unusually quickly for deer, due to quirks in their life history. Although they breed only once a year, they have larger litters than other deer, with triplets being common. Their gestation is also short, although no more so than, say, roe deer, but once born the lightly spotted fawns grow very rapidly. Indeed, they are weaned by just three weeks, after which the mother tends to try and avoid her own offspring, completely abandoning them by the time they are four to five months old. They are sexually mature by six months old (which is to say, the first mating season after their birth) although males may have to wait another year before they'll have much luck finding a partner. This allows them to move into new areas rapidly, although, under more normal conditions, this would be offset by a high mortality rate.

Which at last brings me to the end of the world's living deer species. Some time, perhaps soon, I'll have to say something about how musk deer fit into all this since, as noted above, they aren't actually deer. But before then, I'll take a look at some animals that definitely were, and how deer evolved to their current state.

[Photos by GĂ©rald Tapp, "Heush", and "Altaileopard", from Wikimedia Commons.]

1 comment:

  1. Water deer are quite common in Korea (across most of the peninsula, though more prevalent towards the western side), largely due to predator extirpation. South Korea probably has the largest population of this globally threatened species, yet they’re considered pests (and culled) due to crop damage.