Kelly Mcallister mcallkrm at
Sat Jun 23 23:29:38 PDT 2001

Wayne C. Weber wrote:

> However, it is my distinct impression that Barred Owls generally do not occupy large

> areas of old-growth forest in western Washington, and are more likely to displace

> Spotted Owls from small areas of old-growth or from marginal habitats. Someone who has

> done research on the 2 species in Washington could answer this question better than I.

What an interesting and useful discussion. I can't pretend to have a whole lot of insight
into the relationship between Barred Owls and Spotted Owls but I think that many recently
occupied Spotted Owl habitat areas fit fairly well into the categories "small" or "marginal".
Certainly, many areas occupied by Spotted Owls have significant amounts of old-growth
forest but often in fragments surrounded by young deciduous and mixed forest types. These
situations may well favor Barred Owls. The really extensive old-growth forest tracts, where
Barred Owls may never gain an advantage over Spotted Owls, may be limited to very few places;
perhaps National Parks like Olympic National Park and Mount Rainier National Park. Would the
Spotted Owl population persist for very long if restricted to these two parks? Probably not.

Ulimately, as Wayne says, it is the habitat alterations of humans that cause the loss of species
like the Spotted Owl but it is important to also recognize that habitat loss is working in
a vacuum. There are often complex interactions with competitors that influence whether or not
a species will persist in the face of extensive habitat alteration. In the realm that I am
more familiar with, I believe that many native amphibians would persist in certain severely
altered aquatic environments if it weren't for the competitive advantage provided to the
introduced Bullfrog. It's a matter of habitat alteration tipping the balance in favor of
a competitor that happens to be waiting in the wings ready to come on down and set up
house keeping.

Kelly McAllister
Washington Department of Fish and Wildlife
Olympia, Washington
Reply to: mcallkrm at

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