Sunday 8 January 2017

Ice Age Survivors in Hungary

Asiatic wild ass
The end of the Ice Ages saw a number of extinctions sweep across the world, particularly the Northern Hemisphere. Those animals that did not die out as the climate suddenly became warmer often moved further north, changing the composition of the local fauna wherever they had previously lived. This was no "mass extinction" of the sort associated with the end of the dinosaurs, but, on a smaller scale, it was nonetheless significant.

However, as we know all too well, it was by no means the last time that animals went extinct, let alone the last time that they have been eliminated from some local area. Many of these later extinctions were, of course, due to human activity, especially as we colonised new continents or discovered new islands.

But not necessarily all of them, since the climate has not, in fact, remained constant since the Ice Ages ended. After the sudden thaw that marks the boundary between the Pleistocene and the current, Holocene, epochs, warming continued, but slowed. It reached a peak somewhere around 4,000 to 5,000 BC, and then began a slow cooling that has continued almost until the present. Even that cooling trend has had its fluctuations and reversals, most notably the Medieval Warm Period of the 10th to 13th centuries AD.

And then, as we know, everything jumped off the charts with the advent of the Industrial Revolution. But let's put all of that to one side, at least for today. After all, we have a pretty good idea about what caused mammal extinctions - local and otherwise - over the last couple of hundred years. Let's also ignore the changes to the wildlife of the Americas and Australia that not-so-coincidentally followed the arrival of the white man. Today, I'm instead going to look at local extinctions in Europe itself, following the end of the Last Ice Age, but preceding the modern, industrial, era.

Europe, of course, is a fair size, and it has a wide range of different habitats, from the Mediterranean scrub of southern Spain to the subarctic cold of Lapland, and from the rain-soaked greenery of Ireland to the steppe-lands of southern Ukraine. The European Environment Agency, for example, divides Europe into eleven different "biogeographical regions" based on the climate, fauna, and so on. Even then, some of these are quite broad; both Portugal and Cyprus are "Mediterranean" in this scheme, but they obviously don't have exactly the same wildlife.

To get around this, we need to look at a relatively isolated area. The best example is probably Britain, on account of it being a large island, but another is the Pannonian Basin. This, which constitutes an entire biogeographical region just by itself, is the broad lowland area of central Europe that is surrounded by the Alps, the Carpathians, and the Dinaric Alps. Politically speaking, it's Hungary, with some chunks of the various neighbouring countries thrown in for good measure. Surrounded entirely by mountain ranges, except for the narrow gaps where the Danube enters and leaves, it may not be quite as isolated as an island, but it is surprising distinct, and, perhaps more to the point, easily defined.

Today, the Pannonian Basin is home to a number of different mammal species. On the whole, these are the same that you'd expect to find across much of Europe - mice, voles, red squirrels, badgers, weasels, deer, and red foxes, among many others. There are also wild hamsters and ground squirrels, European wildcats, and, to take two examples that have long since gone extinct in Britain, wolves and wild boar. (No bears, though, although they do live in the surrounding mountains).

A recent review of the literature, however, looked at the various mammalian species native to the Pannonian Basin that vanished from the region between approximately 9,700 BC and AD 1800. It turns out that there are eleven in all, although it's worth noting that most of them still exist elsewhere in the world, and so are only locally, not globally, extinct.

The one exception is the aurochs (Bos primigenius), although even this survives in domesticated form as modern cattle. At the close of the Ice Ages, aurochs were still common in present-day Hungary, but they became much rarer after around 2,500 BC. Nonetheless, they did survive until at least the early medieval period, perhaps only disappearing in the 14th or 15th century AD, which would make them one of the last surviving populations outside of Poland, where they finally died out in 1629. Closely related were the European bison (Bison bonasus), which were common in the area until the Middle Ages, finally vanishing perhaps around the 16th century.

The status of moose (Alces alces) in and around Hungary is somewhat less clear. Typically known in Europe as "elk", we know that they lived in the area up until Roman times, but there is little physical evidence of their existence later than this. Perhaps they just weren't present in great numbers, though, since contemporary records do suggest that they were known in Hungary until at least the 13th century, and probably for some time thereafter. Fallow deer (Dama dama) also present a complicated picture, since they are quite common in Hungary today. However, they were entirely absent from about 2,000 BC onwards, until the Romans introduced a new population from present-day Turkey. Thus, we can list them as a species that went locally extinct, even if they came back later with human assistance.

The steppe pika (Ochotona pusilla) is a small, short-eared animal related to rabbits, and today it lives only in the arid grasslands of central Asia. During the Pleistocene, however, it was much more widespread, doubtless because so was the cold steppe-land that it favours. One might expect it to have died out in Europe when the Ice Ages ended, but it apparently survived for thousands of years in the Pannonian region, since we have found its remains in ancient owl pellets deposited in caves carbon-dated to as recently as 2,500 BC. Similar evidence indicates the presence of narrow-headed voles (Microtus gregalis) over essentially the same time period, despite them having died out elsewhere in Europe at the end of the Ice Ages; today they are found in tundra and steppe regions across Asia and into Alaska.

Another holdover from the Ice Ages may be the bobak marmot (Marmota bobak), known from a single subfossil in the region, dated to somewhere around 5,000 BC. With only one such find known, however, they were probably never very common in the first place.

Wild horses (Equus ferus) lived across much of Europe during the Ice Ages, finding the open grasslands south of the ice sheets very much to their liking. They undoubtedly survived into the Holocene, but quite when they died out in Europe is difficult to say, since it's not easy to distinguish wild from domesticated horses using skeletal remains alone. However, since it seems likely that domesticated horses reached Europe no earlier than 3,000 BC, and at least some Pannonian horse remains are older - but not much older - than that, their local extinction was probably quite late. Wild asses (Equus hemionus) may have survived until around the same time, although it's also possible that they died out somewhat earlier.

The remaining two species listed as pre-industrial extinctions in the region are perhaps, rather more surprising. Not because it's surprising that they went extinct, but because it may be surprising that they lived in Hungary at all after the end of the warm interglacials of the Pleistocene. One of these is the leopard (Panthera pardus), but it has to be said that the authors of the review were unable to find any evidence that this survived in Pannonia into the time period under discussion. However, they assume that it must have, on the basis that there is good evidence that lions (Panthera leo) did so, and that there are no parts of the world today where you find lions, but not leopards.

That seems a bit of a leap to me, but even the fact that were lions in Hungary in post-Pleistocene times is impressive enough. Yet, while some finds of lion teeth and the like may just represent trophies imported from elsewhere, there are apparently enough skeletal remains to suggest that they did indeed do so, perhaps surviving until about 3,000 BC.

Putting all this together, what do we get? Even if we ignore the leopard and the marmot, on the grounds that there is little or no physical evidence to support their long-term presence, that's nine species going extinct in the Pannonian Basin over the 12,000 years or so of the pre-industrial Holocene. But what we notice is that the dates of those local extinctions are far from randomly distributed across that span of time.

Three species, the aurochs, European bison, and moose, have gone extinct relatively recently, roughly in late medieval times. The other six all died out between about 3,000 and 2,000 BC. Which suggests that something happened around that time that had significant consequences for the local animal life. There's no evidence of any great change to the climate then, or any widespread natural disaster, but it does correlate with the dawn of the Bronze Age in the region, when the first Indo-European people arrived from the east and began extensive clearance of the local forests.

The removal of steppe pikas from Hungary is not as dramatic as the near-total removal of American bison from the face of the Earth - let alone the complete removal of animals such as sea mink or passenger pigeons. Nor was it anywhere near as rapid. For that matter, it doesn't even compare to the widespread extinctions following the arrival of Native Americans in America, or Australian aboriginals in Australia. But it does show that Europeans were changing their habitat, and the animals that lived there, long before they started doing the same to other people's continents.

[Photo by Sander van der Wel, from Wikimedia Commons.]

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