[Birding-Aus] Magpie Bills

[Chris Lloyd]

I have dealt with a large number of birds, including magpies, with bill
abnormalities over the last decade or so and the prime reason appears to be
trauma. Some have tried to beat the mouse trap others have simply hit glass
or MVs. Many have presented with other injuries and the bill damage is an
old injury - confirming other correspondents observations that they can
survive.

The bill does not generally re-grow. Bird bills are composed of a number of
outer layers of keratin over partly calcified keratin fibre structure which
has a blood supply virtually to the tip. It is analogous in a rough way to
your finger nail in that the keratin (your nail) grows continuously off a
bone and flesh structure which supply's both reinforcement and a blood
supply to renew the keratin layer. The difference is you finger grows out in
one direction while the bill grows from the inside. This is why bird's bills
often appear flaky at the surface as the older keratin peels or wears away.

Keratin is a protein (the same as feathers and hair) and constitutes most of
the bill's surface it is not a product of calcium consumption beyond some
calcium on the underlying bone fibres. Bill re-growth only occurs when the
underlying fibres and blood vessels have not been badly compromised. Birds
with large bill cracks or where the layers of keratin have been stripped
have reasonable prognosis of full recovery. Those where the bill has been
sheared, bent to the point of stopping blood flow, or punched to the same
effect will not general re-grow their bill - hence the magpies observed. For
some species whose foraging is dependent on a perfectly functioning bill the
injury is a death sentence (many parrots but particularly small ones with
specialised food preferences) while other will cope reasonably well.

Chris Lloyd

chris...@wiyanga.com.au

Logo v5

[Moors]

Many years ago there was a rejected young magpie which we supplemented
with minced beef. We noticed that as a 'teenager', it had protracted
tussles with other magpies the same age. One evening it appeared with
half of its upper mandible missing. For a few days it ate awkwardly
until it was used to the new shape then we noticed it was able to pick
up insects by holding its head sideways on the ground. Very soon it was
good at spearing some meat with the lower mandible and tossing it into
the air and catching the food. After a while it only came to us
occasionally and finally disappeared about 18 months later.

Glenise Moors
Sedgwick

===============================

To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to: birding-a...@vicnet.net.au

http://birding-aus.org
===============================

[Gary Wright]

My wife reminded me that our resident magpie with broken top mandible also
has a club foot, circumstantial evidence for deficiency in diet, although
of course the two may be unrelated. Bird is healthy.

Gaz

[Moors]

Hi Gary,
Some foot deformities are caused by parasites.
Glenise

-----Original Message-----
From: birding-a...@lists.vicnet.net.au
[mailto:birding-a...@lists.vicnet.net.au] On Behalf Of Gary
Wright
Sent: Saturday, 25 February 2012 9:44 AM
To: Moors; birding aus
Subject: Re: [Birding-Aus] Magpie Bills

My wife reminded me that our resident magpie with broken top mandible
also has a club foot, circumstantial evidence for deficiency in diet,
although of course the two may be unrelated. Bird is healthy.

Gaz

===============================