Re: [SBB] Canada Goose - What's wrong with this picture?

["Alvaro Jaramillo" <[[email protected]]>]

Another point:

   These Canada Geese we have breeding in the Bay Area are of mixed stock, a
creation originally to try and re-stock the Giant Canada Goose (maxima) in
the Midwest. Folks then just kept on introducing these mixed stocks
throughout the continent, why, I don't know, but they did. This is where the
largely non-migratory park stock that we see here may have come from. As
such, it is difficult to pin them down to any subspecies but I suspect that
they are mixes of moffitti/canadensis/maxima or something like that. Big
pale races overall. But a general thought about subspecies. They are partly
defined on morphology and partly on breeding distribution. Birds of two
subspecies don't tend to be found in the same area. So if this was a cleaner
(wild) population of Canada Geese we were talking about here, we would not
expect to ever see two subspecies interbreeding, this is because by
definition they would be the same given that they are breeding in the same
area. Therefore we would attribute visual differences to variation within
the subspecies. Note that when we do have some northern geese oversummering
here (White-fronted in Foster City for example) they do not breed, the same
would be expected of any sick or injured migratory Canada Goose that
remained down here for a summer. 

Regards

Al

Alvaro Jaramillo
[[email protected]]
Half Moon Bay, CA

Field Guides - Birding Tours Worldwide
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> -----Original Message-----
> From: [[email protected]] [mailto:south-bay-birds-
> [[email protected]]] On Behalf Of Lisa Myers
> Sent: Thursday, May 11, 2006 2:01 PM
> To: Tiwari, Vivek; SBB
> Subject: Re: [SBB] Canada Goose - What's wrong with this picture?
> 
> Hello Vivek -
> 
> I remember when my goal was simply to remember to call
> this goose a Canada Goose and not a Canadian Goose,
> let alone try a learn all the subspecies.
> 
> Last year in Les Chibana's Palo Alto class he spent
> two nights of lectures going over all the sub-species
> of the Canada Goose.
> Below is a list of what I quickly found on the
> internet.
> 
> Subspecies: Branta canadensis canadensis
> Subspecies: Branta canadensis fulva
> Subspecies: Branta canadensis hutchinsi
> Subspecies: Branta canadensis interior
> Subspecies: Branta canadensis leucopareia
> Subspecies: Branta canadensis maxima
> Subspecies: Branta canadensis minima
> Subspecies: Branta canadensis moffitti
> Subspecies: Branta canadensis occidentalis
> Subspecies: Branta canadensis parvipes
> Subspecies: Branta canadensis taverneri
> 
> So I suspect your pair is a combination of two
> different subspecies.
> I also suspect more information is coming our way.
> 
> Lisa Myers
> 
> --- "Tiwari, Vivek" <[[email protected]]> wrote:
> 
> > Took the following photograph in Alviso on May 1st.
> >
> > http://www.flickr.com/photos/30419272@N00/144705030/
> >
> > Two (presumably) adult Canada Geese with chicks. 1
> > chick visible at
> > bottom of the picture
> >
> > If so, why the big difference in size in the two
> > "adult" birds?
> > Is this a pair? Is there sexual dimorphism in this
> > species? Are these
> > different subspecies?
> >
> > If not a pair, is the smaller, slender bird an
> > immature from an ealier
> > year/brood?
> >
> > Or just a perfectly normal variation, nothing
> > strange here?
> >
> > Don't know if its relevant but the smaller / slender
> > bird appeared to a
> > bare patch of the forehead as seen here:
> > http://www.flickr.com/photos/30419272@N00/144711875/
> > A sick bird?
> >
> > Thanks!
> >
> > Vivek Tiwari
> >
> >
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