Saturday, 17 March 2018

Miocene (Pt 6): The Coming of the Mice

The Early and Mid parts of the Miocene epoch were, for the most part, times when the world was much warmer than it is today. It wasn't a steady pattern, however, and I've already described how the fluctuations in climate, over the course of many millions of years, affected the rodents of Europe. It was a time when the most common small mammals in Europe were not mice and voles, but dormice, accompanied by early hamsters, squirrels, and the gliding eomyids.

By 10 million years ago, however, the colder, drier climate had become locked in for the long term. We know that the forests of Europe changed dramatically at this time, the old subtropical trees, such as figs and palms, being replaced by oak, alder, and elm. Likely as a result of this change in the available food supply, most of the dormice died out, leaving only a few close relatives of the relatively small number of species we have today.

Sunday, 11 March 2018

The Crusty Forearms of Male Bats

Bats, of course, are not blind. There eyesight is, in fact, pretty good in the majority of species. Which makes sense for an animal that has to fly around at night when the light is dim but not entirely absent. It's only for animals like moles, which live underground, where the light can't penetrate at all, that vision becomes an expensive and unnecessary luxury.

Having said that, many species of bat do spend a lot of time in caves, and, in there it really is too dark to see anything, no matter how good your night vision might be. As a result, the other senses of bats are often highly tuned. Hearing is the obvious one, since bats rely on that for their sonar abilities, but many species also have well-developed senses of smell. In particular, since bats also tend to be highly social, scent often forms a crucial part of their ability to communicate with one another - as it does for many other mammal species.

Sunday, 4 March 2018

Silence of the Pacas

Whether or not a given species of animal lives in groups is something of a trade-off. Several different factors are involved, but just one example is that you will simultaneously be more visible to predators and be protected from them by "safety in numbers". For many animals, the benefits outweigh the downsides, although a lot depends on the individual environments and lifestyles of those creatures.

But living in groups also brings its own requirements, perhaps most notably the need to communicate with other members of your herd or pack. Safety in numbers, after all, is of limited utility if one member of the group can't warn others of something dangerous it's just seen. And this isn't simply a yes/no situation; the more complex the group structure, it is argued, the more sophisticated the communication needs to be.