Re: T.Rex Feather Skepticism

[Ronald Orenstein <ron.orenstein@rogers.com>]

At 05:07 PM 9/15/2005, Michael Habib wrote:
> Good point; though altriciality is the ancestral condition for 
> passeriform birds.  The more useful question would be whether 
> passerine birds nesting on the ground tend to become more precocial 
> than those that nest in trees.  There is variation within 
> passeriform altriciality, after all.

I'm not sure exactly what is meant by this, as I do not know of any 
tendency towards precociality in Passeriformes.  It is true that some 
ground-nesting birds, like larks, develop extremely rapidly and 
fledge at an early age - 8 or 9 days in some cases - probably to 
limit the risk of predation, but they are still altricial.  Also, 
probably the longest nestling period of any passerine belongs to the 
Superb Lyrebird, a highly terrestrial species that nests on the ground.

There are some other tricks here - one study showed that the begging 
calls of ground-nesting wood warblers were higher-pitched and more 
difficult to locate than the calls of arboreal-nesting warblers in 
the same habitat.


Ronald Orenstein
1825 Shady Creek Court
Mississauga, ON L5L 3W2
Canada
905-820-7886
905-569-0116 fax
ron.orenstein@rogers.com