Sunday, 14 June 2020

Small Cats: Lynxes of Europe and Asia

Eurasian lynx
Once we get away from the "big cats" as traditionally thought of (lions, tigers, leopards, cheetahs, and so on) the majority of wild cat species are at least broadly in the size range of the domestic animal. However, there are a few cats that are decidedly medium-sized on this particular scale, of which the best known in the Northern Hemisphere are probably the lynxes.

Lynxes are readily identifiable animals, and the word "lynx" itself dates back to at least the Ancient Greeks. They were also one of the original seven species of cat identified by Linnaeus in 1758 when he created the modern system for scientific naming of animals. As early as 1792, they were split off from the other cats into a subgenus of their own, now considered a full genus. This was in Robert Kerr's translation of Linnaeus' original work into English, by which point, at least four different species of lynx had been scientifically named and described (including one by Kerr himself, in the book in question).

The number of species of lynx has varied over the following two hundred plus years, due largely to differences in classification rather than any genuinely new discoveries. As it happens, today, we still recognise four, even if they aren't the same ones known at the dawn of the 19th century.

Linnaeus, of course, was using the lynxes that were local to him as the reference point for his description, so it's those that are, in a sense, the "originals". Today we call that species the Eurasian lynx (Lynx lynx). They're widely spread across the northern parts of the Old World, from northern and central Europe, east to Turkey and Iran, and across pretty much the whole of northern and central Asia, reaching as far south as northern India and Korea. At least in Europe, they once lived even further afield with, for example, one estimate suggesting that they still lived in Britain as late as the 7th century.

The lynx's status as a medium-sized cat seems fairly inarguable. By far the largest of the four kinds of lynx, the Eurasian species is about a metre (3.3 feet) in length and weighs from 15 to 30 kg (33 to 66 lbs) - a little under half the weight of a leopard, but considerably more than even the fattest domestic housecat. Like all lynxes, it has ears with elongated black tufts at the tips, an unusually short tail for a cat, and a sloping back with the hind legs longer than the front ones. The coat is thick, especially during winter, but its markings are highly variable, even with the same subspecies; most are spotted, but the spots vary in size, are sometimes grouped into rosette patterns, and are sometimes faint or even missing altogether.

Another key difference, which may have a lot to do with lynxes being placed in a separate group so early on is that, unlike other cats, they only have a single molar in each side of each jaw. The second one is usually very small in other cat species but it is at least usually there, and makes it possible to distinguish lynxes from other cats on the basis of the skull alone.

For the most part, they are forest-dwelling animals, with almost any deciduous or coniferous forest being suitable habitat. But, as their wide range indicates, they are adaptabe, with some living in the semi-deserts of Central Asia, others on the rocky lower slopes of the northern Himalayas, and others in open scrubland. In the extreme north, they even venture out onto the barren tundra, although not in great numbers due to the limited food supply.

Speaking of which, the primary food of the Eurasian lynx are small hoofed animals. In most parts of their range, this means roe deer, but musk deer and chamois are also major prey items where they are found - studies of lynx in Switzerland have shown that roe deer and chamois together make up 90% of their diet, and that a single kill can feed an adult lynx for about 6 days. Having said which, like many carnivores, they will eat whatever they happen to find that's in the right size range. They'll eat rabbits if they have to, occasionally scavenge on animals already dead, and will certainly kill livestock such as sheep, goats, or semi-domesticated reindeer if that's what happens to be around. They even kill foxes - it's hardly a major part of their diet, but given that not much else does, it's enough to be significant from the perspective of the fox.

Lynx travel around a lot in search of food, although how far this might be for any given animal depends a lot on the local environment, varying by a factor of ten across Europe alone. Males travel further than females, perhaps partly because they are significantly larger and need more food, but also to make it easier to find more potential mates. Females stay apart from one another as far as possible once they reach adulthood, presumably so that they don't have to compete, although individual males may well have overlapping ranges. As we'd expect for cats, males scent mark their territory more than females and tend to mark over anything left by a rival.

Eurasian lynx seem to be more active around dawn and dusk than at other times of the day, although not necessarily by very much, since they make hunting forays both day and night. Females, in particular, avoid human-inhabited areas and may also be more active at night when humans aren't around; this is hardly surprising, since, at least in Europe, human hunting is their primary cause of death although they can learn to be tolerant of humans under the right circumstances.

Mating takes place in March and April, when males scent-mark more, and the cats also call to one another. Pregnancy lasts around 70 days, so that the young are born in early summer. Most litters consist of a pair of kittens, who remain with their mother for between 8 and 11 months and can then travel at least 60 km (37 miles) in search of a home if there isn't anywhere suitable closer by.

Iberian lynx
For much of the 20th century, there were considered to be just two species of lynx, but, in the 1990s, it came to be accepted that the animal we now call the Eurasian lynx was actually three different species. One of these had first been recognised as a distinct species back in 1827, before being demoted to a mere subspecies. Now it has its rightful status back again, as the Iberian lynx (Lynx pardinus).

Native only to Spain and Portugal, this is a much smaller animal than the Eurasian lynx, being only around half the size. It is also more heavily spotted than the Eurasian lynx, and, unlike the latter species, the spots extend onto the tail. The fur also tends to be shorter and coarser, at least as compared with those animals in the more northerly parts of the Eurasian species' range.

Being smaller, Iberian lynxes do not make a habit of eating deer, although they might take the occasional fawn. Instead, their diet seems to consist almost entirely of rabbits, with the remainder made up largely of partridges along with a few ducks, swans, and small mammals. The heavy reliance on rabbits as prey means that Iberian lynxes are really only found in areas where rabbits are common which, in this part of the world, means Mediterranean scrubland and not much else. Unsurprisingly, the presence of nearby water to drink also affects their distribution, as do the presence of trees with large hollows in their trunks, since these are highly prized by the females for birthing their litters.

They are largely nocturnal, probably because so are rabbits - although avoiding humans may well be a factor, too. Despite their smaller size, a rabbit is going to feed an Iberian lynx for far less time than a roe deer will feed a Eurasian one, and they typically need to eat about one every day. On the other hand, they don't have to travel as far to find one, so that they are less wide-ranging than their larger relative.

The obvious downside of having a specialised diet is that if whatever you feed off suffers, so do you. Rabbit populations have plummeted in Spain and Portugal in the second half of the 20th century and this has clearly not helped the Iberian lynx. Human hunting and trapping of the animal has had an effect at least as large, and possibly greater, almost resulting in the total extermination of the species.

Once found throughout the region, and at one point probably into southern France or even northern Italy, today, Iberian lynxes are found in only two small regions of southern Spain, while a 2003 survey found that none were left in Portugal at all. Even the Spanish populations are tiny, each dipping below the minimum number thought necessary to maintain a functional gene pool, something supported by a decline in observed variability in both size and coat colour over the last century.

It's not all bad news, though. The Spanish government launched a campaign to protect the animal in 1994, and the population has started to recover since then. Part of the plan was to allow for cross-breeding between the two surviving populations, boosting their genetic strength, and there have also been efforts to reintroduce the animal to other areas, including one in Portugal. Even so, a census in 2012 estimated that the total population numbered just 156 individuals, not all of which would be breeding adults.

As a result, the Iberian lynx is officially an endangered species. Which is at least a step up from the "critically endangered" status it held until 2015, but hardly a cause for relaxation.

The reconsideration of lynx taxonomy that saw the Iberian lynx returned to species status at the end of the 20th century also did the same for another, similarly sized, species in North America. Next time, I will look at that, along with the one species of lynx that has fairly consistently been regarded as distinct...

[Photos by "Mistvan" from Wikimedia Commons and Programa de Conservaci√≥n Ex-situ del Lince Ib√©rico, from www.lynxexsitu.es.]

8 comments:

  1. Any theories on why the lynx lost it's tail?

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    1. To the best of my knowledge, it's still a mystery. Interestingly, the tail actually has fewer bones in it than in other cats, rather than the bones just being shorter (although they are that, too).

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    2. The ancestor of all lynxes once decided to imitate the man and go ice-fishing in the winter, and stuck its tail in the hole. However, the Lynx fell asleep, and the ice hole closed on his tail, freezing it off. That's why all of his descendents have only a stub tail.

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  2. How do the different lynx species relate to one another?

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    1. There'll be a cladogram in the next post in this series, but the Iberian and Eurasian lynxes are each other's closest relatives, with the Canadian lynx as an outgroup.

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    2. Thanks. So the Eurasian lynx is monophyletic with respect to the Iberian?

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    3. So far as we can tell, yes. I don't know how wide a sampling there has been, so I suppose there could be a surprise in there, but I doubt it, given the size disparity. Their last common ancestor is estimated to have lived in the early Pleistocene, shortly before or around the start of, the first Cenozoic Ice Age.

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