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Re: How Pelicans learn to fish



Any structural convergences in the skull?

Dan

On 11/2/2010 5:21 PM, Mike Habib wrote:
The only diving birds that fold back the wings in a "knife" position are 
gannets and boobies (i.e. sulidae).  Pelicans actually don't tuck their wings all that 
far back on dives; I doubt it's beyond the normal joint excursion for a modern bird.

One bit of interest, though, is that the ratio of bone wall thickness to total 
bone diameter in pelicans is very similar to that in derived pterodactyloids. 
It's about the same as Pteranodon, for example.

Cheers,

--Mike Habib


On Nov 2, 2010, at 7:13 PM, Dan Chure wrote:

Are there any osteological correlates to pelican diving behavior?  One would be 
joints that allow the wings to be rotated backwards, but do all diving birds do 
that or does diving occur in other ways in other birds?

Dan


On 11/2/2010 2:05 PM, Richard W. Travsky wrote:
Of course the first thing I thought of was pterosaurs...

http://www.nytimes.com/2010/10/26/science/26qna.html

Q. How do pelicans learn to dive for fish?

A. Young pelicans learn to feed themselves through a combination of trial and 
error, imitation of adult birds and instinct, bird experts suggest.

In the United States, the Eastern brown pelican (Pelecanus occidentalis 
carolinensis) and the California brown pelican (Pelecanus occidentalis 
californicus) make dives onto schooling fish from impressive heights or float 
on the surface to scavenge fish. A dive from 30 to 60 feet up, or even higher, 
hits the water with considerable force. Fish a few feet below the surface are 
scooped up, and water drains from the sides of the pouch. They tilt their heads 
back and swallow on the spot.

For young pelicans, some early experience in diving for fish comes during their 
time in the nest, when they graduate from feeding on half-digested fish bits 
regurgitated by their generous parents to retrieving fish from the famously 
capacious pouched parental bills and even their gullets. The nestlings may dive 
in shoulder deep to make the parents disgorge fish. Pelicans are well fed in 
the nest for 9 to 11 weeks, by which time they are fully feathered and ready to 
go out on their own.

Their diving success rate is highly variable and depends on experience. Adult 
California brown pelicans bring up fish from around two-thirds of their dives, 
while novices appear to have a lot of trouble; fewer than half survive their 
first year out of the nest.



Didn't know the mortality rate was that high.

Much has been written and speculated regarding pterosaur flying, but
what about smacking the water?



Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280-0181
habib@jhmi.edu