[EBB Sightings] Lake Merritt hybrid pictures

Laura,
These photos really show off the intermediate features of this duck.
Personally, I'm convinced it's a hybrid. There are too many features, both
plumage and structural, that are intermediate between Goldeneye and Hooded
Merganser. It seems implausible to me that a goldeneye would exhibit
apparently multiple mutations that would all tend toward Hooded (or verse
vica). Key features in my mind include head shape (big concave forehead,
shaggy crest, long thin bill) and body color (minimal white in the wings,
gray flanks). The one feature that is not obviously intermediate to me is
the head color, all dark.

Checking breeding range maps and habitats, a Goldeneye x Hooded looks like a
good fit. Range maps show both Goldeneyes overlapping with all 3 Mergansers
somewhere in their summer territory, either in British Columbia, Northwest
Territory, or Alaska. But Hooded breeding habitat comes closest to
Goldeneye. Birder's Handbook describes Hooded breeding habitat as "Forested
habitats, near water, lakes, swamps, marshes, and estuaries." (Erlich,
1988).  Hooded and the Goldeneyes are all cavity nesters. Most telling,
Erlich says of Hooded "Known to share incubation with Wood Duck or goldeneye
females." Circumstantial evidence but Occam's Razor dictates that the
simplest explanation is most likely.


Bruce Mast
 

-----Original Message-----
From: sightings-admin at diabloaudubon.com
[mailto:sightings-admin at diabloaudubon.com] On Behalf Of Laura Look
Sent: Wednesday, January 19, 2005 9:57 PM
To: sightings at diabloaudubon.com
Subject: [EBB Sightings] Lake Merritt hybrid pictures

I've put up a page of representative pictures of the hybrid goldeneye here: 
http://home.earthlink.net/~chamaea/20050119.htm

Does anyone have any further insights into whether it's a hybrid common or 
Barrow's goldeneye?

Thanks,
--
Laura

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