[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: How Pelicans learn to fish



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