Subject: Fw: [bcintbird] Lewis' Woodpecker declines
Date: Nov 25 09:25:18 2000
From: WAYNE WEBER - WAYNE_WEBER at bc.sympatico.ca


Tweeters and Vancouver birders,

The attached message, posted to BCINTBIRD, is relevant to the TWEETERS
discussion on Lewis's Woodpeckers. The major point is that, even if
Lewis's Woodpeckers usually win over Starlings in individual battles
for nest-sites, they may ultimately fail to breed successfully (or
have reduced success) because of the energy lost in having to fight
off 10, 20 or more pairs of Starlings during the nesting season. This
is a hypothesis with which I strongly agree.

The same phenomenon appears to be operating with Crested Mynas vs.
Starlings in Vancouver. I studied the biology of Crested Mynas and
Starlings in the late 1960s and early 1970s. Although Mynas are larger
birds than Starlings, and seem to win more battles over nest-sites
than they lose, the cumulative effect of dozens of such battles during
a season results in Mynas losing the war.

I emphasize that for both Lewis's Woodpeckers and Mynas, this is a
hypothesis only, NOT a proven fact. There is a crying need for a
detailed study into long-term interactions between Lewis's Woodpeckers
and Starlings. As for Crested Mynas, it's too late for such a study--
the North American population is probably down to 20 birds or less. In
the latter case, we seem to be seeing the rich irony of one introduced
species being driven into extirpation by competition with a second
introduced species.

Wayne C. Weber
Kamloops, BC
wayne_weber at bc.sympatico.ca


-----Original Message-----
From: Chris_Siddle at mindlink.bc.ca <Chris_Siddle at mindlink.bc.ca>
To: bcintbird at egroups.com <bcintbird at egroups.com>
Date: Friday, November 24, 2000 7:53 PM
Subject: [bcintbird] Lewis' Woodpecker declines


>Dear Wayne and others,
>
>When Gary Davidson and I investigated Lewis' Woodpecker populations
across
>southern BC for the Ministry of Environment we concluded that
populations
>had dropped seriously since the 1940s and our list of possible causes
of
>decline was remarkably similar to those you summarized in today's
email. We
>also support the idea that European Starling competition for nest
holes has
>a negative effect, though not everyone agrees with us. Although the
>woodpecker seems to come out the victor in nest hole squabbles with
>individual starlings, we suggested that the constant pressure that a
pair of
>starlings can exert upon the woodpecker(s) may be a significant
factor in
>reduced breeding success among Lewis'. Sure, the woodpecker wins the
>battle, but he is exhausted by the lengthy war. The authors of the
Birds of
>North America account for Lewis' woodpecker wrote that this is a
hypothesis
>worthy of investigation.
>
>Incidentally, Gary and I didn't know that a status report was
supposed to be
>brief. We stuffed ours with everything possible until it became a
review of
>life history, etc. The Ministry didn't like it, shelved it, then
hired a
>consultant to edit it. He was paid approximately ten times the
amount for
>which we had contracted to do the original. Two lessons learned
there!
>
>Chris Siddle.
>