Sunday, 21 October 2018

The Best Time for Breeding

Animals, as a rule, want to give birth when their offspring have the best chance of survival. In particular, it's useful to give birth at a time when suitable food is most abundant, whether it's to allow the mother to produce enough milk, or to wean the growing young onto solids more quickly. If the animal in question is short-lived, the time of year may not matter too much, so long as the mother is well-fed and in good physical condition. If you have to breed multiple times each year, you'd better get on with it.

It may also not matter too much if the animal lives somewhere where the seasons don't change too much, although, even in the tropics, where there's no winter, there's usually a rainy and a dry season. A great many mammals, however, do have a specific breeding season, timed to be one gestation-length away from the best time to give birth. If pregnancy lasts six months, and the best time to give birth is in the spring, when fresh plants are sprouting, you'd better do your mating in the autumn. If pregnancy lasts twelve months, however, you want to mate in the spring. And so on.

Sunday, 14 October 2018

Bats That Eat Fish

Greater bulldog bat
With over 1,300 different species of bat known, it shouldn't really be surprising that there's a wide range of different dietary habits among them. Of course, a lot of that is on a fine scale, as I discussed just last month, but there are more significant differences in the kinds of things that bats feed upon. Insects, fruit, nectar, even blood all form the core diet of at least some kinds of bat.

One of the more unlikey food sources, however, is fish. Yet, when you think about it, fish is a really common food source for birds - there are a huge number of bird species that feed primarily on fish, including seagulls, kingfishers, and ospreys, among many others. Clearly, there's no inherent reason why a flying mammal couldn't eat fish, yet very few of them do.

As a recent review makes clear, however, "very few" is not "none".

Sunday, 7 October 2018

Not the Pig Family: Peccaries of the World

Collared peccary
I've already described the anatomical and biological differences which mean that, despite appearances to the contrary, peccaries are not pigs. I've also described all the various living species of the pig family, which means that it's now time to do the same for the living species of the peccary family.

The peccary family is, however, a lot smaller than the pig family: it contains just three living species.

The one that's likely most familiar to readers of this blog is also the most widespread: the collared peccary (Pecari tajacu). It's so-named because of the thin 'collar' of whitish hair that runs from its shoulders across the throat, although, in practice, this isn't always as visible as it might be. The animal is found through pretty much the whole of central and northern South America east of the Andes, through most of Central America, coastal (but not central) regions of Mexico, and into neighbouring parts of the USA, where it can be seen in Arizona, New Mexico, and Texas. If a distinction is needed, this is the true "javelina", since it's the one that's common where that alternative word for "peccary" is most commonly used.

Saturday, 29 September 2018

Lions in the Carpathians

When I last talked about Eurasian cave lions, back in 2013, I said that there was some debate as to whether they were a distinct species, or just an unusual subspecies of the modern, living, lion. Although the issue is, perhaps, still not entirely resolved, it's probably fair to say that the clear majority opinion these days is that they were a separate species (Panthera spelaea).

This swing in opinion has been helped by new genetic data, something that we can obtain because the animals died out so recently - around 12,000 BC by most estimates. Specifically, an analysis published in 2016 was able to obtain the full mitochondrial genome of a pair of cave lions, allowing a more detailed genetic analysis than ever before. This showed that, as expected based on earlier studies, cave lions really were "lions" in the sense that they were more closely related to modern lions than thy were to, say, leopards.

Sunday, 23 September 2018

The Hunting Grounds of Small Cats

The big cats - lions, tigers, leopards, and so on - are arguably amongst the well-known of all wild animals. They frequently figure in zoos and nature documentaries, and, from the scientific perspective, they have been the subject of numerous studies down the years. Even the medium-sized cats, such as lynxes, bobcats, and ocelots, are well known, and, at least in the case of the European and North American species, also well-studied.

We know somewhat less about the assorted species of genuinely small cat - the ones that are about the size of the typical domestic moggy. Yet there are an awful lot of them, even if most members of the public would likely have a hard time naming more than one or two.

One such example is Geoffroy's cat (Leopardus geoffroyi) named for - though not discovered by - the pioneering French naturalist Étienne Geoffroy St Hilaire. This lives in southern South America, reaching Bolivia, Paraguay, and the southern tip of Brazil in the north, and also found just over the border in Chile, but mainly inhabiting Argentina and Uruguay. While they prefer terrain with scattered trees and plenty of bushes, the also live in open grassland, and are found right down to the very southern coast of South America, although not on the islands beyond.

Sunday, 16 September 2018

Modified Munchies of Many Mouse-eared Myotises

In the modern system of taxonomy for the classification of living things, a genus is  group of closely related species. It is the lowest mandatory level of classification, apart from 'species' itself, and forms the first half of a creature's scientific name. Thus, Panthera, for example, is the genus containing lions, tigers, leopards, snow leopards, and jaguars.

As such, we'd typically expect a genus to contain only a small number of species - it is, after all, the smallest standard grouping of species that there is. And, at least for mammals, this is typically the case. Many genera, in fact, have only one known species, or at least only one that isn't extinct (as is the case for our own genus, Homo, for example). But there are some exceptions, cases where there are so many incredibly similar species that we just have to lump them all together.

The single largest mammal genus, as commonly defined today, is Crocidura, which represents nearly half of every species of shrew we know about. But even the second largest, Myotis, is a whopper.

Sunday, 9 September 2018

The Pig Family: Peccaries Are Not Pigs

Over the the year so far, this series has described every living species of pig. Yet there are some animals that might seem to be missing. Found across much of Latin America, and up into the southwestern USA, we can find animals known as peccaries. These certainly look like pigs, and, unlike razorbacks, which can also be found in the US, they are genuinely wild animals, not the descendants of domesticated ones that happen to have escaped.

The reason I haven't mentioned them so far is, as the title of the post makes apparent, that they aren't actually pigs. So why the heck not, and what are they, if they're not pigs?