[Tweeters] RE: Western Screech-Owl declines

Charles Swift charless at moscow.com
Wed Mar 9 15:19:29 PST 2005


I appreciate Wayne's comments and have to admit that I missed the earlier
part of this discussion (including Wayne's post) so am at fault for missing
important parts of it. I have been mostly checking tweeters on
birdingonthe.net so do not always get the full thread. Also admittedly I
should have done more research before blatting out but there you go. At
least I prompted an interesting reply from Wayne!

Much of what Wayne mentioned can also be found here:
http://www.speciesatrisk.gc.ca/search/speciesDetails_e.cfm?SpeciesID=720

I only have a few specific comments below with regard to Wayne's comments.

>-----Original Message-----
>
>I disagree with Charles that "you need more than anecdotal evidence
>for a species to be considered for a watchlist". For a start, this
>recommendation conflicts with the "precautionary principle", a basic
>tenet of wildlife and fisheries management. For Western Screech-Owls
>and a number of other bird species, it may be that anecdotal evidence
>is the only kind of evidence we have for a decline. Once a species is
>placed on a watchlist (or the "Special Concern" list in BC), this is a
>signal that more specific and detailed monitoring studies, which will
>provide objective information on population changes, need to be
>carried out. Hopefully, placement on such a list will attract funding
>to carry out needed studies.
>

Point well taken. But in general, wildlife managers are much more likely to
take notice if there is a dataset documenting declines. If we were actually
employing the "precautionary principle" there would probably be a lot more
species on watchlists. This may be a good case in point. If anectodatal
evidence is all that is needed then why isn't it on the WA Audubon list (see
below). This may be a difference between what we would like vs. what is
reality.

http://wa.audubon.org/new/audubon/userdocuments/State_of_the_Birds_LR.pdf

>I believe Charles may also have misinterpreted the comments about the
>effects of Barred Owls on other owl species, because he used the
>subject line "owl competition" in his message. I believe that the
>effects of Barred Owls on Spotted Owl populations are mainly
>competition, but those of Barred Owls on Western Screech-Owls are
>mainly predation (although they could be competition as well).

I should have used predation/competition in my subject line. It seems
possible that Barred Owls could be competing with Screech-Owls for a similar
food source if they are overlapping in habitat use. I personally would like
to see more evidence of large owl - small owl predation (more than just
"anecdotal"!)
>
>In southwestern BC, I am certain that habitat loss is NOT the main
>cause of recent Western Screech-Owl declines, although it is probably
>a contributing factor.  In many areas around Vancouver, e.g. parks,
>the habitat is little changed from 30 years ago, but Western
>Screech-Owls have declined from fairly common to non-existent.
>

I am interested to know if Barred Owls are also using parks in Vancouver or
if this just an indicator of decline elsewhere. In the Puget Sound area I
presume that Barred Owls & Western Screech-Owls are primarily using low to
mid elevation conifer forests.

>I'd like to repeat the final paragraph of the message I sent out on
>March 1, with which I hope Charles (and most of the rest of you) would
>agree:
>
>"At any rate, the ecology of Barred Owls deserves far more attention
>than it has received in BC and WA (and also in OR and NW CA). They
>appear to be a major factor in the decline of both Western
>Screech-Owls and Spotted Owls, *but this needs to be confirmed by
>thorough scientific studies*."

Agreed, although there do seem to be a lot of people working on Spotted Owls
in WA, OR, and CA and at least some of them are interested in Barred owl
ecology. Of course the big question is funding and most would agree that
wildlife research in the U.S. is way under-funded.

thanks, Charles.

~~~~~~~~~~~~~~~~
Charles Swift
charless at moscow.com
Moscow, Idaho
~~~~~~~~~~~~~~~~





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