The Roosting Hypothesis

[Jason Brougham <jaseb@amnh.org>]

Not much research has been done into what animals are capable of at the edges 
of their abilities. Like pinioned pochards climbing 6 foot fences, or 1 day old 
chukars climbing 60 degree inclines.

Yet, this must surely be where selection pressure is strongest and where 
evolution happens. If a population of animals is routinely at the edge of its 
physical capabilities, any mutation that helps would likely be incorporated 
into the gene pool and propagate rapidly.

Ken Dial has done the most work on this subject, probably, though he is reallyh 
interested in the flapping aspect. Nonetheless he found that ground based birds 
don't even bother flapping their wings until they are climbing an incline 
steeper than 45 degrees. And 1 day old chicks climb 60 degree inclines just by 
pushing down with their forelimbs, not really flapping.

There are a lot of fallen branches and snags reaching the ground at 60 degrees 
or less in any wild forest after every big storm.
________________________________________
From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of David 
Marjanovic [david.marjanovic@gmx.at]
Sent: Friday, July 12, 2013 9:43 AM
To: dinosaur@usc.edu
Subject: RE: Yet more on pterosaur quad arm posture

> OK, my incredule, here is a flightless Weka (Gallirallus australis) in a
shrub:
>
> http://www.flickr.com/photos/trs/3476131920/
>
> And, as I say, chicks and pinioned birds that can't fly do it too.

Let me just quote from what it says under the photo:

"Wekas really aren't meant to be off the ground, and the best part was when 
this particular one kept falling off the branch. I saw this silly bird on Ulva 
Island, a small island in a bay of Stewart Island."

"The tree was more of a large shrub, and it hopped up from branch to branch."

Seriously, this does not count as climbing.

> Of course Strigops does as well, but it is zygodactylous, after all.

It's a parrot. Parrots _are_ good climbers.