Sunday, December 15, 2013

Local species debate

 Rocky Mountain elk near Manhattan, MT.

A few months ago a bow hunter in Oregon (who also happens to be co-worker of my dad's) killed a possibly record setting trophy bull elk near the town of Sweet Home, Oregon. My dad says when the skull rests on the ground, the antlers tower over his head.

It hasn't been published in any hunting magazines yet because the official antler score depends on which subspecies of elk it is, and that is under debate. There are two subspecies in Oregon: Rocky Mountain (Cervus elaphus nelsoni the most numerous and widespread subspecies in North America, also called American Elk) and Roosevelt (Cervus elaphus roosevelti a relatively rare species found mostly in the Coast range mountains and foothills. Supposedly darker in color, larger, with shorter, thicker antlers that often have an extra tine near the top that sticks out at an angle. I say supposedly because, really, if you stood two average specimens next to each other, you probably couldn't tell the difference.)

Likely, it will be determined to be a Rocky Mountain elk because  Boon and Crockett use the I-5 freeway as a subspecies boundary. According to them (and other hunting organizations), Roosevelt elk are only found West of the freeway, and everything to the east is Rocky Mountain territory.

I'm sure this was an arbitrary choice on the part of Boon and Crockett - I-5 convienently runs almost straight north-south and bisects the Willamette Valley, and it's probably true that Rocky Mountain elk won't be found West of the freeway. But Roosevelts are definitely found on both sides of the freeway.

The red line is I-5, the orange line is the crest of the Cascade mountains. The red circle is the area the elk was killed. The mountain range is most likely the true subspecies boundary, if we can draw such a thing. This elk was smack in the middle of territory where both subspecies mingle, though you'd be hardpressed to find that information anywhere official.

The Oregon Department of Fish and Wildlife doesn't have their own boundary per se, but they do have management units. The trophy elk was taken either in the Santiam or Mekenzie unit, and both of those units are considered "Western Elk" not "Eastern Elk".

It's OK, though. No one really agrees about the ranges of the elk subspecies.

 Most of the maps you see online look something like this. Which is interesting in a couple of ways. One, it implies there's no overlap between the Roosevelts and rocky mountain populations, which is obviously wrong. Two, the ranges are too small overall. Not only are elk found throughout the Cascades, well into Northern California, they also are on both sides of the mountain range. Here is a photo of some elk in Bend, OR, which is located well to the East of the Mountains and well outside the range for either elk species. Here's another in Malheur, also well into a "white zone".

Hunters report elk throughout the entire state of Oregon, though most range maps show large empty white areas in the east and south.

This map from California Fish and Wildlife at least shows the ranges of the Roosevelt and Rocky Mountain touching. But I took this photo of some elk about 80 miles northwest of Sacramento, quite a few miles farther south than the official Tule elk population.

It makes sense - like their cousins the white tailed deer, elk habituate to humans fairly well. They do well in a wide range of habitats and eat a wide variety of plants; they breed fairly quickly and reach sexual maturity quickly. Though I doubt we'll see the same explosion in urban and suburban populations like we had with the white tail, elk populations are just going to go up.

And the boundaries between subspecies are probably a lot murkier than most people realize. I have no doubt subspecies are interbreeding in the Cascades and foothills on either side. And I wouldn't be at all surprised if northern populations of Tule are mingling with southern Roosevelt. Big whoop, subspecies interbreed all the time. But it'd be nice if someone besides the locals were tracking this kind of thing.

No comments: