Subject: How about the songs and calls of Black-throated Gray/Townsend's hybrids?
Date: Jun 3 21:35:06 1999
From: Michael G. Shepard - mgs at orcatec.com


I've inserted some comments below.

Michael G. Shepard
Director
VGI Vision Foundation
5325 Cordova Bay Road, Suite 211
Victoria, BC V8Y 2L3
c/o (250) 658-4844 telephone
(250) 658-0084 fax
mgs at orcatec.com

-----Original Message-----
From: Michael Price [SMTP:mprice at mindlink.bc.ca]
Sent: Sunday, May 23, 1999 8:26 PM
To: tweeters at u.washington.edu
Subject: Re: How about the songs and calls of Black-throated
Gray/Townsend's hybrids?

Hi Tweets,

Michael G. Shepard, in speaking of warbler hybridism, writes:

>I have a strong suspicion that a substantial proportion of the birds
[Black-throated >Gray Dendroica nigriscens and Townsend's Warblers D.
townsendi] may be
>hybrids. We are now catching hybrids annually at the Rocky Point
>Migration Monitoring Station at the southern tip of Vancouver Island. A
>few are distinctly intermediates, while most are Black-throated Grays with
>a few Townsend's characteristics such as greenish backs or yellow flecks
on
>the breast.

I'd be very surprised if the hybrid-zone between these two was restricted
to
Vancouver Island but wasn't also on the mainland.
On May 31, I encountered both species on the Sechelt Peninsula (mainland).
The habitat was nearly identical to that of my study area on Vancouver
Island: second-growth Douglas-fir forest with occasional big-leaf maple and
other deciduous trees interspersed.

Also, is there an actual
increase in the number of hybrids of Hermit Warbler D. occidentalis and
Townsend's showing up in the Canadian Southwest? What are the chances of a
*pure* Hermit's?

Incidentally, I was in on the sighting of the first Hermit Warbler for
Vancouver BC at Queen's Park during a big fallout there in the early
1990's.
Even though the bird clearly had a greenish back color identical to
townsendi, conspicuous coarse black streaking all down one side of its
breast to the lower flank area and fine black streaking down the other, and
a very pale suffusion of yellow on the upper breast, it was still accepted
by the rest of the Vancouver Rare Birds Committee as a pure Hermit Warbler,
and is in the official record as such, though these features *clearly*
indicate a hybrid parentage.

>Is anyone else seeing or catching these types of hybrids?
Sievert Rohwer et al. collected a specimen of a hybrid Black-throated
Gray/Townsend's from the Gold River area on Vancouver island. I believe a
note or article was published in either the Auk or Condor. There have been
a few sight records in the Pacific states.

Michael, try going out in the forest and singing 'Buddy, Can You Spare a
Gene?' and see what their DNA looks like. I understand the
Hermit/Townsend's/Black-throated Gray complex is gonna be a real headache.
Can anyone fill us in on the latest?
As far as I know, there is only the one specimen. DNA work using feathers,
or blood samples preferably might illuminate the situation.