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Re: How Pelicans learn to fish
Any structural convergences in the skull?
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.
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?
On 11/2/2010 2:05 PM, Richard W. Travsky wrote:
Of course the first thing I thought of was pterosaurs...
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.
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205