Swan Geese in North America are going to be either recent escapes from a
private collection or feral and descended from domesticated birds. I ran
into a flock of seven unbanded Swan Geese near Astoria many years back and
all had a characteristic large knob at the base of the upper mandible.
These knobs are sure indicators that the birds are from domesticated stocks
as the wild birds in Asia almost always lack them. If there are no knobs
then they're most likely from a private bird collection. The wild birds
also have less white in the face and neck~ still pretty neat to find them
out here!
Happy Birding,
Theodore Squires
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