compete for the same resources. Other problems, which might be less obvious, include the fact that infections and parasites are more likely to spread amongst a group of similar animals that remain in close contact. All of these are good reasons for solitary living, as seen in a great many mammal species.
Despite which, of course, there are many mammals that do live communally. For these animals, whatever costs there may be are obviously outweighed by the benefits, of which there are several. While a large group of animals may be easier to see, it's also easier for them to keep a lookout, since not everyone needs to be actively scanning the horizon (or whatever) all of the time. They can also share in communal tasks, such as child-rearing, putting less strain on the individuals. Predators that hunt in packs can take down prey far too large for any one of them to kill on their own. Even huddling together against the cold can be a worthwhile benefit.
Sunday, 28 April 2019
Sunday, 21 April 2019
Nonetheless, there is a biological group that we can call, for lack of a better term, the "true rats" (technically the "Rattini") which includes the animals that most people likely think of when the term "rat" is used with qualification. There are two species of this kind of animal in Britain, not least because both of them are found just about everywhere else as well.
Sunday, 14 April 2019
While there was nothing similar in the south, there had been plenty of cat-like animals on the northern continent before. True, they had not literally been cats, but rather nimravids, a group of remarkably cat-like animals that lived long before actual cats existed. The climatic changes of the Early Miocene seem not have suited them, however, and almost died out as the new epoch dawned. It's possible that one, Dinictis, a bobcat-sized sabretooth, did manage to struggle on for a few million years, but even that is debatable. But, otherwise, while their relatives, the barbourofelids, continued on in Europe, to eventually be replaced by actual cats, in North America... there was nothing.
Sunday, 7 April 2019
Fighting back, as larger horned animals might do, generally isn't so effective, although skunks (for example) have certainly found a way of doing that. But there is also the option of body armour. It's something we see quite a lot in reptiles and, in living mammals, it's perhaps best developed in armadillos. But body armour doesn't have to be a bony or keratinous shell, for something that wants to avoid being eaten, spines can also be an effective deterrent.