Rob's comments are valid and it's true that species deal with
competition all the time - in the short term and in the longer
evolutionary sense. What Rob has not put into his equation is the human
factor. It is humans that have reduced the habitat of Spotted Owls to
the point where they may not survive (in BC at least). This and other
habitat alteration (by humans) is thought to have allowed the Barred
Owl to make its rapid advance southward through BC. Barreds are also
possibly to blame for the decline of smaller forest owls on Vancouver
Island. A similar situation exists with the dramatic westward expansion
of the range of Brown-headed Cowbird. Will species adapt (i.e. evolve)
to compete with these rapid incursions of other species? No, as Rob
points out, we don't know the answer. But I can't accept that it is
"natural" when human influence has been such a factor. Are we a
"natural" part of our ecosystems? Well, there's a tangent to go off on
...

As an interesting aside, some years ago I had one of these "birders and
movies" moments, when a Barred Owl called in the film "The Milagro
Beanfield War" which was set in southern California. No Barred Owls
there at that time, but I bet it is only a matter of time. I wonder
what species will be forced to adapt there?


Bruce Whittington
Ladysmith, BC
mailto: fieldnat at pacificcoast.net