Re: Again :-] : Re: Again: origin of bird flight

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

> If, OTOH, the predator jumps off from 2 m, the jump lasts so long that the
> prey will escape in too many cases.

This only applies when the predator is Wile E. Coyote and the potential prey 
is Road Runner.  Wile E. Coyote possesses the selectively advantageous trait 
of having a lag between the moment when he realises he's suspended in 
mid-air and the moment when gravity begins to have an effect.

For all other predators, the time it takes to fall is not too different 
between whether the height is 1m or 2m above ground.  I could do the math, 
but it might be better simply to climb a tree with a stopwatch and see for 
yourself.

;-)

> Hunting frogs is difficult. Considerably larger size, and maybe arboreality
> or an ability to swim, will help.

Once, several years ago, when standing on my patio, I spied a frog in my 
backyard - siting maybe 3m away.  The patio was about 1.5m above the lawn.  
I clambered over the railing of the patio, and jumped onto the lawn, landing 
within about 1m of the frog.  I could have landed closer to the frog, but I 
didn't want to land right on top of it.  There was no water or trees nearby, 
and I could have easily have pounced on the frog and caught it.  But I'm not 
a natural predator of frogs, and (outside of French restuarants) I don't 
usually eat them.  I observed the little frog jumping away, in the direction 
of the rockery.


Tim

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

Timothy J. Williams

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

Phone: 515 294 9233
Fax:   515 294 3163

_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com