Sunday, 23 July 2017

Is the Dormouse an Endangered Species?

At first glance, this seems a fairly daft question. A moment's search on the internet will reveal that only is the dormouse not an endangered species, it isn't even under any significant threat of becoming one. It's about as safe as any species that doesn't specifically rely on human beings can be. There is no risk that we are going to, at any point in the foreseeable future, even come close to running out of dormice.

Look past the headlines though, and things do become a little more complicated. No, the dormouse is not an endangered species, but its population is under threat in certain parts of its range, particularly in the northwest. Some of these populations are isolated from the main bulk of the species in mainland Europe by the presence of various seas, and perhaps the most obvious of those is the British population. Since this population lives on a (relatively) northerly island, and since there are, apparently, risks to the dormouse in the north of its range, it is, in fact, reasonable to ask whether or not the dormouse is an endangered species in Britain.

Sunday, 16 July 2017

Pinnipeds: Decline of the Monk Seals

Mediterranean monk seal
(museum specimen)
The great majority of seal species are found in cold, often freezing waters. Even harbour and elephant seals, which are frequently found in temperate, or even subtropical, climes, also inhabit colder latitudes for at least part of the year. There are just three modern species of true seal that are found solely in warm waters, and they all happen to be closely related. These are the monk seals.

It's not actually known why these animals are called "monk" seals. The oldest known reference to the term comes from Johann Hermann in 1779, when he wrote the first scientific description of the Mediterranean monk seal (Monachus monachus), and gave it its scientific name. The only reason he gave for doing so was that he'd heard that the animal was called that in France, and thought that maybe that was because, seen from behind, the head and shoulders looked a bit like a robed and hooded man. But he was guessing about that latter part, and there doesn't seem to be any independent corroboration that the animal really was called a "monk seal" in France (or, indeed, anywhere else) prior to his naming of it. Presumably, he'd got the name from somewhere, but, for all we know, he might have misremembered the details.

Sunday, 9 July 2017

First and Last of the South Asian River Dolphins

South Asian river dolphin skeleton -
note the strange shape of the skull
Although the whales are undeniably spectacular, the majority of cetacean species are much smaller; the sort of animals we generally refer to as "dolphins". The great majority of these belong to the family Dephinidae, variously termed the "oceanic dolphins", "pelagic dolphins", or even "true dolphins". This is a large family, with nearly forty species, including killer whales and pilot whales alongside their smaller kin.

Whatever we call this family, it, in turn, belongs to the larger group of the "delphinoid cetaceans", which also includes the six species of the porpoise family and two other whales - the narwhal and beluga. Taken together, these animals and their extinct relatives have dominated the count of cetacean species across the world for millions of years, forming a key part of the ocean ecology. Of all the other cetacean groups, only the mysterious deep-sea beaked whales come close in terms of the number of species, and even they don't appear to be as varied.

Sunday, 2 July 2017

The Social Lives of Elephants

Indian elephant
Elephants are the largest land-dwelling animals alive today. They are also among the most intelligent non-primate species, with complex social lives, and, as I noted in passing a few weeks ago, seem to be able to pass the Mirror Test for self-awareness - the only mammal, other than apes or dolphins, for which there is reasonable evidence of this ability.

There are many reasons that we'd like to know more about the lives and habits of elephants; even leaving pure curiosity aside, on a practical level it might help us to find ways to manage elephant populations so that they can peacefully co-exist with our expanding agricultural and residential footprint.

But there is a problem to really getting to grips with elephant "societies" and how they function. That's because, in addition to being large, elephants are also remarkably long-lived. If you go out into the wild and study a herd of elephants for five years, you will get a lot of information, but it's really just a snapshot of what's going on in the course of their lives. Elephants can live for at least seventy years, and a generation lasts for about 25 years, so getting a really good picture of an elephant's life would take... well, a human lifetime.

Sunday, 25 June 2017

Rain Down on Me: Wild Boar and the Weather

Wild boar (Sus scrofa) are very far from being an endangered species. They are found across continental Europe and Asia, and on a number of nearby islands, from the Mediterranean to Japan. We have no idea how large their global population is, but it's clearly pretty big, and they are common animals in many places. But even if their very existence isn't in danger, that doesn't mean that we have no need to figure out how to properly manage their populations in the wild, so as to cause neither humans, nor the boars themselves, any inconvenience.

This is in part because the influence of wild boars on humans is mixed. On the one hand, they can be quite a nuisance. They cause significant damage to crops, can spread diseases to farm animals (most obviously, pigs), and caused almost a thousand traffic accidents a year in northwestern Spain. Clearly, these are all good reasons to keep their numbers down, at least in places where humans are common - which, let's face it, mean pretty much the whole of Europe. On the other hand, wild boar are generally regarded as quite tasty, which, while it's not a great thing to be from the boar's point of view, does at least mean that hunters don't want to drive them away into really remote and inaccessible areas.

Sunday, 18 June 2017

Pinnipeds: Hooded and Bearded Seals

Hooded seal pup
Most of the species of seal found in the waters of the North Atlantic are roughly the size of harbour seals, with full-grown males measuring about 160 cm (5' 3") in length, and weighing around 120 kg (265 lbs); females, of course, are somewhat smaller. Of the three species that are significantly larger than this, the biggest of all are the hooded seals (Cystophora cristata). While not a patch on the largest seals of the Pacific, with males up to 270 cm (8'9") and weighting around 300 kg (660 lbs), they're still pretty hefty.

Hooded seals live relatively far north in the Atlantic, spending most of their time in cold waters northward from Nova Scotia to the coasts of Greenland and Iceland, and some of the remote islands that lie to the north of Europe. They are known to have four, relatively small geographic areas in which they do their breeding - the Gulf of Saint Lawrence, off the north coast of Newfoundland, the Davis Strait between Greenland and Baffin Island, and around Jan Mayen island east of Greenland. Although these appear to be quite distinct, there is no evidence of any significant genetic difference between the populations, and hence, no recognised subspecies of the animal.

Sunday, 11 June 2017

Age of Mammals: The Miocene (Pt 1)

Five years ago, I started a series of posts in which I looked at the world, and its mammalian fauna, during the time of the Ice Ages. My plans as to how I was going to do that changed quite rapidly, and the earlier posts aren't really in the same format that I later settled in to. Nonetheless, since that time I have covered not only the Pleistocene epoch of the Ice Ages, but also the Pliocene, which immediately preceded it. Yet, even taken together, these two epochs represent only a relatively short slice of the Age of Mammals.

We currently divide the Age of Mammals - the time since the extinction of the non-avian dinosaurs - into three broad periods: the Paleogene, Neogene, and Quaternary. The last of those includes only the Pleistocene and the brief, human-dominated, time since it ended. The Neogene, however, is also dominated by more-or-less modern kinds of animal, and it is further divided into two epochs: the later Pliocene, which I have already covered, and the earlier Miocene, which I haven't.

Perhaps the first thing to grasp about the Miocene is that, compared with the epochs that followed, it is remarkably long. It lasted, as currently defined, from about 23 million to 5 million years ago. That makes it over three times as long as the Pliocene and Pleistocene put together. As you might expect, the world changed far more over this timespan than it did during the subsequent epochs; we're not just talking a couple of million years here, but it a much more substantial chunk of time. It's only because it's so much further back that it makes sense to do this - we just don't have the same sort of fine detail available, since so much of it has been erased in the time since it all happened.