Dear Jack and Tweeters:

Thanks for the correction on ptarmigan distribution. As Jack
pointed, out, Rock Ptarmigan do occur in the NORTHERN Rockies of B.C.
(north of Pine Pass). I should have said that Willow and White-tailed
Ptarmigan occur together without Rock Ptarmigan in the CENTRAL Rockies
(between Yellowhead Pass and Pine Pass.). There are a number of
records of Willow Ptarmigan, including breeding records, in the
Central Rockies in both B.C. and Alberta.
I also erred in stating that Willow Ptarmigan do not occur south
of the Skeena River, although there is an area of southwestern B.C.
where both Rock and White-tailed Ptarmigan occur without Willow
Ptarmigan. (I seriously wonder about the accuracy of the Willow
Ptarmigan breeding record reported from Garibaldi Park in Campbell et
al. The timberline willow-thicket habitat preferred by Willow
Ptarmigan is generally absent in the mountains of southwestern B.C.)
Rock Ptarmigan have been proved to breed in the mountains west of
Howe Sound, within sight of downtown Vancouver, and there is at least
one June record from Mount Seymour, just north of town. For years, it
puzzled me that in both the Vancouver area and the Sunshine Coast
(Gibsons) area, we have a lot more records of Rock Ptarmigan than of
White-tailed. However, this agrees with the habitat preferences
described by Weeden in his Ph.D. thesis, and summarized in "The Birds
of Chilkat Pass" (Canadian Field Naturalist 74:119-129, 1960). Rock
Ptarmigan occur and breed in rocky areas around and even below
timberline (about 4500 to 5500 feet), whereas White-tails tend to
occur higher up, in areas much less accessible to hikers and birders.
Jack is also quite correct in stating that we have a lot to learn
about ptarmigan distribution in B.C.; there are large areas where
ptarmigan undoubtedly occur, but we have no information on them.
Thanks also for your comments on the habitat preferences of "brown
thrushes" in central and northern B.C., Jack.

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


-----Original Message-----
From: Jack Bowling <jbowling at direct.ca>
To: tweeters at u.washington.edu <tweeters at u.washington.edu>
Date: Thursday, June 17, 1999 7:25 AM
Subject: Re. Brown thrushes


>Wayne W. wrote -
>
>
> (big snip)
><<< I hasten to add that my experience that 2 species of brown
thrush
>do not usually breed in the same forest stand does not always hold in
>other parts of North America, where different habitat types occur,
and
>other species of thrush (Gray-cheeked Thrush, Bicknell's Thrush, and
>Wood Thrush) are added to the equation. The range of habitat types
>used by a species depends on the range of habitats available, as well
>as on the presence of other potentially competing species.>>>
>
>There are 3 species of catharid thrushes in the northern half of BC -
>Swainson's, Hermit and Gray-cheeked. Hermits like young/scrub
>conifer/deciduous type habitats; Gray-cheeked like mostly
>moister willow/alder scrub apparenty; and Swainson's more mature
>deciduous/confier mix. I have almost zero experience with
Gray-cheeked.
>In my experience, there is little overlap in breeding habitat
selection
>between Hermits and Swainson's: one would not expect to find
Swainson's
>in pine flats, nor would one expect to find Hermits in big tree
forests.
>
>(snip)
>
><<< One of the things that I find intriguing about the
>Veery/Swainson's Thrush/Hermit Thrush situation is that there is, in
>general, an altitudinal succession of species, with Veeries at the
>lowest altitudes, Swainson's in the middle altitudes, and Hermits at
>the higher altitudes, although there is a lot of overlap.>>>
>
>With latitudinal compression of biotic zones, this altitudinal
>zonation disappears north of about Quesnel or 53 degrees north in BC.
>
><<< A similar situation, where you get an altitudinal succession
of 3
>closely-related species (over a narrower range of altitudes) was
found
>by Robert Weeden, who studied ptarmigan (Willow, Rock, and
>White-tailed) in the Chilkat Pass area of extreme northwestern B.C.
He
>found that Willow Ptarmigan nested at the lowest altitudes, in the
>dense willow thickets above the limit of conifers; that Rock
Ptarmigan
>occurred higher up, in alpine vegetation above the willow thickets;
>and that White-tailed occurred highest, where the landscape was
>dominated by rocks and scree rather than vegetation. Once again, the
>picture changes in areas where one of the 3 species drops out, such
as
>the northern Rockies of B.C. (where there are White-tailed and Willow
>but no Rock Ptarmigan), or in the Coast Range between the Skeena
River
>and Vancouver (where there are Rock and White-tailed Ptarmigan but no
>Willows).>>>
>
>Bzzztt. Rock Ptarmigans indeed do occur in the Northern Rockies,
e.g.,
>the female myself, Chris Siddle, Gary Davidson and Linda van Damme
>witnessed near the Summit Lake radio tower in Stone Mt. P.P. July 1,
>1986 (willow thickets at this elevation, too). The species has also
>been reported from Pink Mt. Anyone making bold statements about
>ptarmigan distribution in BC will be talking mainly through their hat
>since there has been very little work done on alpine avian species
>anywhere in the province.
>
><<< When I say that two species of "brown thrush" do not usually
>breed in the same forest stand in our area, I'm trying to describe
the
>big picture, and there may be some local exceptions. Would anyone
else
>like to share their experience with these species?>>>
>
>I agree with the general statement. Note that Swainson's coexist
>happily with Varied Thrushes and Am. Robins so the habitat selection
>seems to be catharid specific.
>
>-------
>Jack Bowling
>Prince George, BC
>jbowling at direct.ca
>