Re: soggy "down" maladaptive?

["Tim Williams" <twilliams_alpha@hotmail.com>]

Ken Kinman wrote:

>     Another argument put forward by Feduccia and others is that downy
> feathers would be maladaptive as insulation (soggy feathers result in
> hypothermia at night?) unless it was only on the young and a parent could
> shield the young from getting its down wet.

Hang on...  Didn't these same people just claim that the temperature of the 
Mesozoic was too *warm* for any theropod to require insulation?


>     How does one best argue against the "downy feathers get soggy and are
> thus maladaptive" argument?


Hesperornis.

Feather impressions found associated with one hesperornithid specimen are 
very hair-like, and more like the down feathers of modern birds than flight 
feathers.  Yikes - hesperornithids spent almost all of their time in water!  
No wonder they went extinct!!  The poor things were hypothermic!!


Penguins.

For the most part, as above.  And they live in the Antarctic.  Can't get 
much colder and wetter than that.


Kiwis.  Emus.  Ostriches.  Rheas.  Moas.

I've walked through a forest in New Zealand - it can be a very wet and damp 
experience.  I know kiwis have their problems, but hypothermia as a result 
of being wrapped in damp, wet "maladaptive" feathers is not (AFAIK) one of 
them.  Implying that feathers are only useful when they are used for flight 
suggests that every secondarily flightless bird should dispense with 
feathers.  They haven't.

It also rains in the Australian outback and African savannah.  Emus and 
ostriches do get wet.  They live to see another day.


Tim



------------------------------------------------------------

Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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