Certainly a nice close photo, to which I will comment on this and other
comments:
The serrations are normal and usually hidden when the beak is closed. I don't
know if these structures are in the bone at all. I suspect not, (I do have a
swan's skull in my collection and don't recall seeing this). It is likely to be
just part of the keratin layer of the beak. Some cartoonists like to show
birds with teeth, Daffy Duck I think commonly. Maybe that came from pictures
like this one. Anyone could easily say it looks like it has teeth but it does
not, of course.
As you have noticed, there is a bit of cranial kinesis there, although in the
reverse of what we usually see, as in it is extending the jaw hinge from the
base (I think anatomically moving the quadrate bone forward without moving the
palatine bone,) rather than extending the tip.
As for where to find Black Swans outside Aus. They are....... I was a bit
surprised to see them in a botanical garden adjoining the zoo in Wuhan, China.
Philip
-----Original Message-----
From: Con Boekel
Sent: Sunday, 8 May, 2016 11:29 AM
To: canberrabirds chatline
Subject: Image of Black Swan
Hi
This is an unusal image in that it shows the beak serrations which are normally
not visible. I have searched the readily available on-line databases without
being able to see something similar. This bird, and what I presume to be its
partner, were engaging in some mutual behaviour that involved both birds
sitting absolutely still in the water, facing each other and with the lower
mandible held closed at the tip but with the serrations showing. I am not sure
whether the birds had lowered the jaw end of the mandibles or whether this is
even possible.
regards
Con
Details
Black Swan
Gungahlin Pond
Image captured: 5 May 2016
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