Monday, August 09, 2010

Vole Patrol

Voles, voles, everywhere.

As the Idaho Mountain Express reported last week, much of southern Idaho is experiencing a vole population explosion this summer.

Montane voles are small but stocky rodents that live in large colonies. You might see them scurrying across the road or trail. Or you might notice their well-developed trails through sagebrush, meadows and agricultural fields.

Some reports point to this vole abundance as a sign of nature "out of balance," an assertion that is not correct.

Voles populations are cyclic, and at times the little animals exist in staggering numbers.

And wherever there are large numbers of prey animals, there will be a lot of predators taking advantage of the situation. Whether it's wildebeest in the Serengeti, mayflies on a spring creek, or snowshoe hares in the Arctic, huge masses of prey invite a feeding frenzy.

And that's certainly the case with high vole populations. So many predators eat voles--foxes, coyotes, hawks, owls, weasels, snakes. And, oh yes, trout.

Visit Silver Creek in the evening and note the high numbers of owls around. It would be interesting to know if the owls have more young, or raise young more succesfully, in years of peak vole abundance. In Alaska, lemming population booms mean more breeding by snowy owls and short-tailed weasels. Perhaps voles--which are similar to lemmings--affect Idaho predators' survival and breeding success.

The concept of the "balance of nature" makes a good story, but it's never really been accurate. Nature sometimes appears, to human eyes, to be wildly out of balance. But huge population outbreaks are not necessarily plagues or natural disasters; instead, they're merely part of a natural cycle of prey and predator.

This summer, keep an eye out for voles and the many animals that eat them. It may be a while before we ever see this many again.

1 comment:

Sue Choppers-Wife said...

Oh, we'll see them! I live in Pocatello and have been plagued with what I thought was a mouse or rat issue in the house all winter. The funny thing is that food did not seem to be the draw and no trap worked...not even live traps. It/they mostly used very strange areas to go to the bathroom. Now that spring is arriving I haven't noticed any new sign inside.

But there are a ton of trails coming from my massive spruce hedge in the back yard...and I finally identified the culprits...sagebrush voles. They really are sort of cute with their stubby little tails. They are also renowned for being almost impossible to trap, so things make more sense now.

I knew when the snow melted and I saw all the trails and scat that I will be seeing loads of predators this year. My yard is fenced (doesn't stop the deer or moose lol) but I will assuredly be seeing a lot on bull snakes and the raptors are already scoping it out.

I live on a bench and have nothing but BLM sage and juniper behind us, not surprised they like the protection of the hedge :) I hear they keep the grasses down too, that's a good thing in fire country.