Thursday, August 04, 2005

Spotted owl and Barred owl smackdown

Before I begin this, let me say that I am no biologist, and the information I have regarding owls is through reading and from impressions I get from foresters and my company’s wildlife biologist.  Secondly, I am not even attempting to do this because I want to copy RoguePundit’s fantastic style, with his random nature posts.  Working for a timber company, the issues around Spotted Owls interest me.  So here we go.

Now, Spotted Owls, or Strix Occidentalis, inhabits must of the western coastal forests, and also parts of the southern Rockies, down into Mexico.  Many people will split those species into different families, like Western Spotted Owl and Northern Spotted Owl, but they are basically the same bird.

When you hear the words “Spotted Owl” the term “old growth” usually enters the picture as well.  Scientists have thought for a while now that the owls prefer older stands, or a mixed canopy with older and mature conifers mixed with younger trees.  Great battles in the 80s and 90s between environmentalists and timber interests gave us the environment that folks working in the forests have to deal with today.

Restrictions vary from state to state, but typically you have to leave an area within a circle of anywhere from three quarters of a mile radius to one and a half miles radius around a nesting owl site.  Some of that timber can be harvested, but you have to leave a large percentage, and you can’t harvest trees at all within a core zone around the identified nest.

Spotted Owls eat a variety of rodents and other small mammals, and even snakes, beetles, and other large insects.  They will mate for life, but don’t always breed every year.  They average about 2 or 3 eggs when breeding, but are wimps about protecting the next from predators.  Being small for owls, they are predated by other large birds, including the Great Horned Owl and red-tailed hawks.  To avoid being eaten they require denser forest conditions.

Which brings up an interesting point, which I’ll get more into later.  When environmental thinking people think of old growth (whatever that means) they think of the sections of federal forests with large trees and lots of space under the canopy.  But Spotted owls don’t need, and tend to be unsafe in, conditions of that sort.  Spotted owls have been seen nesting and foraging in a variety of conditions, including riparian areas with lots of hardwood trees.  Our biologist found one nesting in a large red alder.

Enter the Barred Owl (Strix varia).  Looking at pictures of both owls, you might not get the differences right away.  The Barred owl looks strikingly like the Spotted owl, and indeed they come from the same stock.  The big difference, physically, is that the Barred is bigger. 

The Barred and the Spotted owl were believed to be separated during the ice age, cut off by the ice sheets in Canada.  As they will not travel over the mid-western plains, where there is no tree cover, the two populations got separated for millennia. 

The Barred owls have been slowly migrating back to the west via the Taiga forests of Canada.  Lately they have made their way down into Washington and Oregon.  I had heard that biologists didn’t think they would cause the Spotted Owls much trouble down as far as California, but apparently that’s not the case.

      There is nothing that says old-growth louder than the northern spotted owl. There are no forests more closely identified with old growth than those in Redwood National and State Parks. It stands to reason that you should be able to see or hear a spotted owl, then, in those parks. It's more likely that this year, you would be sorely disappointed. 

      "If people are coming here wanting to see a spotted owl, we would have to say, not really anywhere,'" said parks wildlife biologist Kristin Schmidt.  "From my perspective, it's awful. I feel like our park has been infested with something."

      The hoot that you may hear now is from an invader, a barred owl. It's like a spotted owl on steroids. The eastern bird's rapid colonization of the West Coast's best old-growth territory has been recognized -- but not so openly discussed -- for years.  The barred owl's southward surge and expansion does not bode well for the spotted owl.

This article does a pretty good job of talking about the differences between the two owls.  The Barred owls are bigger, they breed a little more regularly, or rather, if the brood is lost they can try it again in the same season.  They are more likely to protect the nest, so the infant mortality is far less.  Great Horned owls are their only natural enemy.

Barred owls are aggressive, and will fight Spotted owls for nest spots, and they are close enough, species-wise, that the Barred owl can successfully breed with the Spotted owls, driving the males away.

Barred owls also tend not to be as picky where their habitat and food is concerned, giving them more advantage in changing environments.

We’ve been stewing for a while on the knowledge that the Spotted owl’s days in Washington state were numbered.  And yet the state continues to mandate, and in some cases make tougher, the regulations designed to try and help spotted owls.  They don’t seem to get that they are disappearing for natural reasons and not because of us.  Take this article, which doesn’t even acknowledge the Barred owl as an issue, but seems to be fixated on the inadequacy of the current owl circle regulations to protect the owls.  Denial.

Back to the article I linked to above.

      It would be a great irony -- but a reasonable possibility -- that the spotted owl's last secure foothold may not be the grand old-growth forests that were the subject of the great environmental battles in the 1980s and 1990s, but the younger stands of Northern California created by intensive logging.

It seems that the Spotted owls do better in timber country, as they are smaller and can fly in the thicker stands of trees with low canopy.  Also, the wood rat density in commercial timberland is 16 times what it is in old growth.  Wood rat being the primary food for owls in those areas.  So the Spotted owl might still hang on if the Barred owls keep to the older, more spacious forests.

This part of the article cracked me up, though.

      And while they are an invasive species like pampas grass or English ivy, removing them might not be as palatable. Conservationists at a recent two-day workshop of owl experts from around the West warned of a public relations uproar. And many scientists and land managers said they couldn't bring themselves to shoot a barred owl.  But is this science or sentiment?

      What might be learned from shooting barred owls, and watching how their smaller cousins respond, could be valuable to land managers and scientists. "Controlled experiments are the purest form of inference," said University of Minnesota researcher Rocky Gutierrez at the Humboldt State University conference.

      Removal projects could reveal how barred owls recolonize areas, and whether spotted owls will move back into areas they've been ousted from. They may shed light on how extensive removal programs need to be, and where -- in what forests or topography -- they are effective.

      The California Academy of Sciences has been asked by the U.S. Fish and Wildlife Service to take 20 barred owls from the Klamath National Forest.

      It's a routine academic collection focused on one area to watch the reaction of the two species. But Lowell Diller, senior biologist for Green Diamond -- a company whose Habitat Conservation Plan centers on spotted owls -- said removal should be a last resort in a conservation strategy, even if it might be successful in the short term. Habitat selection may be more effective and easier to sell, he said.

So now we’re going to shoot one species because it’s taking out an endangered species?  I didn’t know that piece of legislation was intended to prevent other animals, other than humans, from killing endangered species.

Now, if you are killing, or removing, the birds purely for the sake of scientific study, to see how they move in and drive off other owls, then fine.  That sounds like fun, and probably beneficial to science.

But they better not be doing that for the purpose of relieving the Spotted owl’s troubles.

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