Sunday, 12 May 2013
So how can we study what they're up to? For land animals, there are a number of options. You could, of course, just watch them, and, for many purposes, that's enough. But if you want to know where they go on a 24-hour basis, that's not really going to work. For one thing, it's impractical, and, for another, you'll likely annoy the animal, so that (even leaving ethics aside) it isn't going to act normally. So, if you want to study an animal's movements over a long period of time, your best bet is to catch the animal, and fit it with a GPS tracking device. Then, having released it, you wait a while for it to calm down and get used to this collar thing around it's neck, and then see what it does.
Sunday, 5 May 2013
|Got any apples?|
Humans change the landscape around them, merely as a product of how we live. In order for our own species to survive, for instance, we need farmland, and lots of it. That brings competition with local wildlife, even if we're trying quite hard not to. Planted fields, and even open ranchland, are a change to the natural environment, and that's sure to have some effect. And that's before we start thinking about urban development.
Still, even leaving aside the fact that we can't really do without cities and towns, some animals have done quite well out of them. The house mouse is a particularly extreme example, and essentially doesn't live in the wild any more. But many other animals live in our cities, and even find them a benefit. Think of rats, pigeons, cockroaches... okay, so perhaps they aren't our most welcome neighbours, but from their perspective, we're rather a good thing.
And then there's animals that do well on the fringes, in the suburbs, or patches of urban greenery: urban foxes, badgers, raccoons, and so on. There's a balance for these animals to draw, between the risks of, for example, being hit by a car, and the advantages of nearby rubbish bins. Many of them become nocturnal, even if they aren't naturally, because that's the best time to be out and about if there's lots of humans nearby.
Sunday, 28 April 2013
Since there are rather more lowland areas than there are mountains, goats could spread much further than they could during warmer times. When the Ice Ages ended, and the hot weather returned, they simply headed back up the mountains. But not, necessarily, the same mountains that they had previously come down from.
As a result, we now have quite a range of goat species across Asia, and, to some extent, Africa. After all, between (and after) the Ice Ages, each population was isolated from those in other ranges, and could develop on its own. Taking, at least for today, our definition of 'goat' to be "any species from the genus Capra", there are probably at least seven, and maybe eight or nine, wild species of goat. The wild goat itself is one, and the markhor, with its bizarre corkscrew horns, is another. Most of the others are collectively known as "ibexes".
Sunday, 21 April 2013
The mammoths in question arrived from Asia, crossing over the Bering land bridge, the recurring appearance and disappearance of which greatly influenced North American wildlife during this time. They were southern mammoths (Mammuthus meridionalis), the dominant species of mammoth in Asia at the time, but they quickly evolved into a home-grown American animal: the Columbian mammoth (Mammuthus columbi).
It used to be thought that, even ignoring any late-surviving southern mammoths, there were at least two different species of mammoth living in North America in the early to mid Pleistocene. We're now pretty confident that they're all just examples of Columbian mammoth. Nonetheless, you will often see references to the "Imperial mammoth" (Mammuthus imperator). Perhaps the biggest elephant that has ever lived - they were about thirteen feet tall at the shoulder - these were probably just really big Columbian mammoths. Not that that's anything to sneeze at, mind you.
Sunday, 14 April 2013
|Mediterranean water shrew|
But, of course, they often do. For example, there are fifteen different species of insect-eating bat in Britain alone. But if you have two different kinds of animal living in the same place, in the same way, eating the same thing, they have no choice but to compete. Inevitably, one of them will be slightly better at it than the other, and, given enough time, one of them has to either die out or change what it's up to. So how come there are so many similar animals?
Generally speaking, the answer is that they're not all doing exactly the same thing: there's some subtle difference in what they're up to. In some way or another, they're partitioning the available resources. One simple possibility, for instance, is that they aren't eating the same thing after all. If (to pick a rather unlikely hypothetical example) one of you eats only raspberries and the other eats only blackberries, there's plenty for both, and you don't have to fight over who gets to eat what.
Sunday, 7 April 2013
|The Ngorongoro Crater|
Long-term population studies are one way to achieve this. If we can look at a population of animals over the course of several generations, we can map declines and rises against the times that various events occurred, to see which are most important, and how easy it was for them to recover from temporary problems. If we study several species at the same time, we can also see whether some events that were good for one species were bad for another - a vital piece of information if we want to protect both of them.
Saturday, 30 March 2013
The reason for this is their extreme hardiness. Adapted to living in habitats even more marginal than those of sheep - which, at least in their wild form, are themselves more resilient than, say, cows or pigs - they're ideal for raising in the sort of scrubby environments that you get in much of Africa and the Middle East. Even so, after approximately twelve thousand of years of selective breeding, the domestic goat has come a long way from its wild ancestors. They're often larger, with smaller horns, or none at all, and some have long, floppy ears. There are a number of different breeds, from milk-producers like Saanens and Toggenburgs, to the muscular Boer goats, bred for their meat, to the long-haired angora and cashmere goats that produce fine wool and mohair.