Saturday, July 18, 2009

What happened to the Yellowstone elk

Ever since wolves were reintroduced to Yellowstone in 1995, elk populations have been declining and everyone had an opinion as to why. Local hunters say it's simple: wolves are voracious, Godless killing machines and they've been eating them all. Biologists don't think wolves can eat enough elk to account for this level of decline, and wolf advocates have pointed at the long drought period that began in the 1990's and hasn't really ended.

Scott Creel, a Montana State researcher believes he has the answer: it's the wolves, but not because of how many elk they eat. It's the way the elk have to behave in order to avoid being eaten. His study indicates that elk nutrition levels are low in late winter, which is reducing the reproduction rate. The calves aren't all being eaten; they're not being born in the first place.

Creel believes that without wolves, the elk could spend their winters in open meadows that supplied plenty of healthy grass. Now it's too dangerous to graze in the open, so they're spending more time higher up in the forests, where the browse is less nutritious. If this is the case, then the lower populations levels may represent a new equilibrium and even an improvement in the weather is unlikely to restore the higher elk numbers.

[via Ralph Maughan's Wildlife News]


James Hanley said...

Hmm, My first thought was that it was probably a behavioral response to the presence of wolves, but I didn't intuit what specifically that response might be.

Does that make me half-bright?

Scott Hanley said...

Or, following Daniel Dennet, would being "half-bright" mean you're an agnostic?