No Boys Allowed

Even in mammals that are otherwise social, it is quite common for males and females to live apart for most of the year. The most common pattern involves females living in groups with their children, until the latter approach adulthood, while males either live alone, or in much smaller bands, outside of the mating season. In many hoofed herd animals, however, the males live in herds that aren't much smaller than those of the females - in other words, both sexes live in herds, but the two don't mix until it's time to do the necessary.

Clearly, these are creatures that benefit from the group protection that living in herds provides, and, while there's obviously a limit on how large a herd can be before there isn't enough food to support them all, it's not always so clear why the herds should be single-sex. Why, in short, do so many hoofed herd animals practice sexual segregation?

There are a number of theories, and, as is often the case, they aren't mutually exclusive. Nor is it likely that the reason - or the balance of reasons, if there's more than one - will be the same for every species. It's something we have to examine on a case-by-case basis.

Caprines: At Last, The Goats

Wild goat

In English-speaking countries, and, for that matter, South America, sheep are a far more common sight on farms than goats are. (To be fair, in much of the US, even sheep aren't as common as they are in Britain, let alone Australia and New Zealand). However, while the worldwide population of sheep is, indeed, higher than that of domestic goats, it's not by as big a margin as you might think. In particular, goats are a vital mainstay of the agricultural economy in India, and throughout much of Africa.

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.