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Re: T.Rex Feather Skepticism

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
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