WESTERN BLUEBIRDS-- MIGRATORY OR RESIDENT?
enhunn at attbi.com
Fri Mar 15 17:58:36 PST 2002
Wayne et al.,
Most of the King County breeding records of Western Bluebirds are from
Weyerhauser lands east of the Snoqualmie Valley, that is, recently cut over
lands in the lower foothills of the Casdades. I suspect such areas are quite
inhospitable to bluebirds in the winter. The Mountain Bluebird nesting seem
concentrated in clear cut areas higher in the Cascades, above ca/ 1000 m.
Bluebirds certainly don't winter in those areas. So it is possible these
bluebirds move to lowland sites, but there are very very few winter records
from anywhere in the vicinity, so I suspect they move over longer distances,
perhaps to California.
----- Original Message -----
From: "Wayne C. Weber" <contopus at shaw.ca>
To: "TWEETERS" <tweeters at u.washington.edu>
Cc: "MICHAEL HOBBS" <hummer at isomedia.com>; "RUSSELL ROGERS"
<rrogers122 at attbi.com>; "MIKE PATTERSON" <celata at pacifier.com>; "EUGENE
HUNN" <enhunn at attbi.com>
Sent: Friday, March 15, 2002 8:44 AM
Subject: WESTERN BLUEBIRDS-- MIGRATORY OR RESIDENT?
> Michael, Gene, and Tweeters,
> The main thing I was trying to suggest in my previous message was that
> the WESTERN BLUEBIRDS reported at Juanita Bay Park could have been
> locally-wintering birds-- not necessarily newly arrived migrants,
> although the latter is at least equally likely.
> Michael's comments that Juanita Bay is "nowhere near known nesting
> areas for Western Bluebird" does not totally agree with the
> information I have. The book "Breeding Birds of Washington State"
> shows confirmed breeding localities in the Carnatian-Duvall area and
> in south-central King County. There is also a sizable and widespread
> breeding population in Pierce and Thurston Counties. Maybe my
> definition of "near" is not the same as Michael's.
> Do the birds from Pierce & Thurston Counties all head south in winter?
> If so, I would be surprised, because Western Bluebirds in southern
> B.C., both coastal and interior, are (or were) at least partly
> resident. I also had the impression that they were largely resident in
> the Willamette Valley of Oregon, where they are fairly common (Perhaps
> Mike Patterson could enlighten us here?)
> The Western Bluebird population on southern Vancouver Island and the
> Gulf Islands of BC-- which died out completely during the 1980s-- was
> largely resident, as indicated by Christmas Bird Counts at Victoria as
> high as 59 birds in 1964 and 55 in 1959.
> In the Okanagan Valley of BC, probably 80% or 90% of Western Bluebirds
> go south in winter, but the Penticton CBC usually tallies 20 or 30
> every year, with a high of 61 in 1995.
> In the southern B.C. interior, Western and Mountain Bluebirds
> generally breed in different habitats (grassland and grassland edges
> for Mountain Bluebirds, open pine forest for Westerns). I have seen
> many large flocks of migrating Mountain Bluebirds, but have never seen
> Westerns in with them, although I know of a few reports of mixed
> flocks. Mountain Bluebirds usually arrive before March 10th in the
> Okanagan Valley, although the peak migration is in late March and
> April. Western Bluebirds (according to Cannings et al. in Birds of the
> Okanagan Valley) usually arrive about a week or so later than the
> first Mountains, with an average "arrival date" of March 18.
> In the Vancouver area, Mountain Bluebirds are scarce but regular
> spring migrants, with an average arrival date of April 1, varying from
> March 6 to April 25 (18 years' data). Western Bluebirds have been seen
> there only about 5 times in the last 30 years, although they bred
> there prior to the 1960s.
> So I don't believe Western and Mountain Bluebirds generally migrate
> together, although they may do so in some cases.
> The Western Bluebird is certainly an intriguing species. Its
> disappearance as a breeding bird from most of western Washington and
> southwestern B.C. in the last 50 to 60 years is unexplained, and
> probably not mainly a result of Starling competition, because most of
> the decline occurred before Starlings arrived. (I know that Russell
> Rogers and others have given considerable thought to the reasons for
> the decline.) I agree with Michael that there is "a need for much more
> data"-- we should be carefully monitoring the status of this species.
> Wayne C. Weber
> Kamloops, BC
> contopus at shaw.ca
> ----- Original Message -----
> From: Michael Hobbs <Hummer at isomedia.com>
> To: Wayne C. Weber <contopus at shaw.ca>
> Cc: Tweeters (E-mail) <TWEETERS at u.washington.edu>
> Sent: Thursday, March 14, 2002 4:17 PM
> Subject: Re: Western Bluebird -- arrival date?
> Wayne - Data are scant, but this year's sighting at Juanita and last
> sighting at Marymoor are nowhere near known nesting areas for Western
> Bluebird. Whether this represents a small amount of migration west of
> the Cascades, or whether this is some kind of pre-breeding
> exploration, it would seem reasonable that there be some seasonality
> to this movement.
> The biggest assumption I made is that it might be related to Mountain
> Bluebird movements, which I don't expect (based on Marymoor data) to
> begin here until next week. Western and Mountain Bluebirds winter
> together in some areas (i.e. New Mexico) where they do not breed, and
> breed in some areas (B.C.) in which they do not winter. So it seemed
> possible to me that they might migrate between those locations
> together. Townsend's Solitaire might also be part of this movement,
> A huge leap, perhaps, which clearly points to a need for much more
> Michael Hobbs
> Kirkland WA
> hummer at isomedia.com
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