Hi Nancy, et al.
I look at all North American Common Mergansers to make sure they are
not vagrant Goosanders from Eurasia. Many people think that
"Goosander" is just the Eurasian name for Common Merg; however, they
are not synonymous. The name "Goosander" actually refers to the
Eurasian nominate subspecies (Mergus merganser merganser) which is
different from our North American subspecies (M. m. americanus). The
differences deal primarily with head shape, bill shape and color, and
wing pattern (when seen in flight). Goosanders have been recorded in
Western Alaska and perhaps even in the Pacific Northwest. American
Common Mergansers have been recorded several times in Europe.
Since these taxa are field identifiable, it is good to know about
them, since splits are always a possibility.
(There is a third subspecies in southern Asia, M. m. orientalis,
which is more like the European Goosander subspecies, but I don't
believe it is that a much of a factor in North America.)
I googled around for a good identification web site that directly
compares the two, but can't locate an on-line source that really
treats the two forms side-by-side. (Be careful on the web, many sites
erroneously interchange images and drawings of the two forms.)
Here's a good image of a male Goosander ... note the distinct hook at
the end of the bill of the Goosander ...
http://www.birdguides.com/iris/pictures.asp?f=195045
.. compared to your male bird ...
http://www.flickr.com/photos/34312269@N04/3310762051/in/set-72157614384267699/
YourTriadelphia birds look like good americanus forms.
More than you (n)ever wanted to know, I'm sure ...
Phil
At 09:54 02/26/2009, Nancy Magnusson wrote:
>Last weekend at Brighton Dam, there was a lot of common merg
>courting going on. I have been trying unsuccessfully to find photos
>of this behavior on the web. I've posted a series of photographs I
>took of one pair on Flickr just in case anyone else is interested.
>
>http://www.flickr.com/photos/34312269@N04/sets/72157614384267699/ -
>once in Flickr, click on the thumbnail and then select "All Sizes"
>to see the slide fullsize.
>
>Brighton Dam is the lower end of Triadelphia Reservoir between
>Howard and Montgomery Counties.
>
>Nancy Magnusson
>Ellicott City, MD
===================================================
Phil Davis, Secretary
MD/DC Records Committee
2549 Vale Court
Davidsonville, Maryland 21035 USA
301-261-0184
mailto:[log in to unmask]
MD/DCRC Web site: http://www.MDBirds.org/mddcrc/rcindex.html
=================================================== |