The Annual CBC data for Western Screech-owl from 1990 on shows a steady
decrease in number of birds per party hour in Washington State. Many of
our CBCs are in the Puget Sound, an area where the Barred Owl has made
significant headway in recent years. While the CBC is not rigidly
scientific, it does provide an indication of what is going on.

For those interested, the website:

http://audubon2.org/birds/cbc/hr/graph.html

>From there, go to the graphing selection, and make selections. Kind of an
interesting site. Might want to pull up the Barred Owl data too...

-Jamie




> Hi All >
> Anybody who has taken a wildlife population ecology course will tell you
> that it is very hard to prove cause and effect relationships when it comes
> to interspecific competition. There could be all sorts of reasons why
> Western Screech Owls are declining (if they are declining) that have
> nothing
> to do with Barred Owls. You need more than anecdotal evidence (although it
> is a good starting point) and that can be hard to produce. Although not a
> professional myself, I have recently taken a pop. ecology course and this
> was really hammered home - I'd be interested to hear from some of the
> professional wildlife folks on tweeters on this topic.
>
> Likewise I would imagine you need more than anecdotal evidence for a
> species
> to be considered for a watchlist. So if there is good documentation of
> declines for Western Screech Owl (published or unpublished data) then I'm
> sure it would be a good candidate. Of course owls, being fairly cryptic
> species, are difficult to census. Some areas (e.g. Canada) have instituted
> systematic owl monitoring projects to try to get at this. Birders can
> certainly help with these kinds of projects - for example there are many
> Breeding Bird Survey (BBS) routes around the country that go unrun every
> year.
>
>
> thanks, Charles.
>
> ~~~~~~~~~~~~~~~~
> Charles Swift
> charless at moscow.com
> Moscow, Idaho
> ~~~~~~~~~~~~~~~~
>
>
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Jamie Acker
Bainbridge Island, WA
Owler at sounddsl.com