Sunday, 23 July 2023

A Puma's Larder

Most animals, mammals included, spend a considerable proportion of their time either eating or searching for something to eat. Foraging for food is not necessarily difficult in the case of grazing animals, since grass is usually plentiful where they live, but for most others, it is not quite so simple. There is generally a pay-off of some kind to be made between how nutritious the food might be and the amount of energy that would be expended in finding it - as measured by the time spent searching and the area that needs to be covered to do so. And then there's the amount of energy that will be expended in acquiring the food once you've found it; easy enough if you're a herbivore or even a scavenger, but possibly requiring a fair bit of effort if you're trying to kill something.

But that's not necessarily the end of the story. Many animals cache a proportion of their food, saving it for later. One immediately thinks, perhaps, of squirrels storing their nuts so that they can come back to them in winter when food is in short supply. Many burrowing rodents do something similar, hoarding food in underground chambers that can return to at their leisure. But carnivores can cache food, too, despite the fact that meat tends to go off more quickly than properly stored nuts or grain.

Sunday, 16 July 2023

The Stinky Family: Skunks

Unlike raccoons, there was relatively little confusion on the part of early zoologists as to what general sort of animal the skunks were. Since the animals are not native to Europe, the first Europeans knew of them was when they reached the Americas. The closest analogy they could think of among familiar animals was a polecat, and in some parts of America, they are still referred to as such today. However, an indigenous name for the animal (probably Algonquian) won out in English, and "skunks" they became.

Skunks did make it on to the first recognised list of scientific animal names in 1758, as Viverra putorius - the latter half of which, again, means "polecat". The first half indicates that Linnaeus, probably having only a minimal description to go on at the time, considered them to belong with the civets and mongooses, as a sort of generic small, bitey, mammal. That did not last; in 1795, an encyclopedia jointly published by  Cuvier and Geoffroy gave them their own genus. The name for this, Mephitis, comes from a goddess of noxious underground gases worshipped in pre-Roman and Roman Italy - the sort of thing that only tribes living near a volcano are likely to come up with. 

Sunday, 9 July 2023

Oligocene (Pt 3): From Musk Deer to Hell-Pigs

The Grande Coupure that marked the beginning of the Oligocene in Europe did not have as dramatic an effect on the cloven-hoofed animals as it did on some other mammalian groups. But the change was nonetheless noticeable, with several primitive forms that had once inhabited the continent suddenly dying out as it merged with Asia. Others, however, survived through the break, and the absence of their earlier competitors may even have helped them prosper.

These include the gelocids, which first appeared close to the end of the previous epoch. Few of the known fossils of these animals are in good condition, and there is some debate as to whether they are a true group of animals at all, or just a vague term used to collect similar-looking creatures that we can't place elsewhere. That aside, we can at least say that they physically resembled (but were probably not related to) musk deer. That is, they were relatively small, hornless animals with long legs suited for running fast, but lacking the large fang/tusks that mark true musk deer. They did well enough that some, such as Pseudogelocus, are known not only from France and Germany, but also Mongolia, suggesting that they crossed over in the opposite direction to most other mammal groups.

Sunday, 2 July 2023

The Sex Lives of Female Jaguars

There are many ways of classifying mating systems in animals, but one of the most basic uses four main types. In polygynous species, the male mates with as many females as he can get away with, driving away or out-competing any potential rivals. This ensures he can sire as many children as possible, while the female gains the advantage of a strong father for her offspring. This pattern is perhaps seen most strongly in deer and seals, but it's also seen, for example, in lions and gorillas. 

Monogamy is somewhat less common. Sometimes, it happens only because the species is sufficiently widespread that any given male is unlikely to find more than one receptive female during the breeding season, but it can also occur by choice, typically where raising young is a sufficiently arduous task that the father has to stay around after the birth to help. This is commonly associated with birds, but many mammals also form pair bonds for raising young. These include species of gibbon and small antelope that, in paternity tests, have shown essentially 100% loyalty to their mates. The prairie vole is well-studied in this regard, with the formation of the pair bond through prolonged and repeated mating having been linked to, among other things, the "cuddle hormone" oxytocin.