Beaver

Today's Animal of the Day is one of the true keystone species of the world. This term is bandied about pretty frequently, but shouldn't be--- a keystone species is not just a species that is "important" and deserves to be protected. Rather, a keystone species is one that has a disproportionate effect on its environment. In any given ecosystem, the removal or addition of certain species will have a much greater effect overall than the removal or addition of others. It is along these lines that we come to understand that the beaver is one of the most disproportionately influential species on Earth. This should be understood on both ends: the removal of beavers from locations where they were previously found has a large effect, and the introduction of beavers into water systems where they previously weren't found also has a large effect.

The reason beavers are so influential is because of their status as ecosystem engineers. As you might imagine, the physical characteristics and realities of the waterways in an ecosystem have a huge impact on the composition, distribution, and population sizes as well as interactions of the species in the system. Thus, when beavers change the flow and level of rivers and streams by building dams, they have a direct impact on a huge number of species around them.

You might be thinking that a beaver would have to build a really big dam to have such a big effect. The biggest dam ever discovered was 2,140 feet long, 14 feet high, and 23 feet thick at the base.

There has been a lot of interesting research about the stimuli that cause beavers to have the impulse to build dams. For instance, beavers will pile branches next to a loudspeaker if it is making sounds like a running river!

Sorry it's been so long. It's going to be a busy couple of weeks. I hope to keep the blog going, but probably will just have links instead of longer, textual entries.

Cheers,
George