This article claims that this very large extinct condor
(Argentavis magnificens) had a glide ratio of 3% at
67 kph, which is about 33:1. This is better than many
older and some newer (e.g. PW5) gliders. So much for
evolution!

Del Copeland

At 17:24 13 February 2008, wrote:
Hi Gang
This is a tough and pretty rigorous article on the
flying
characteristics of todays' and yesterdays' large soaring
birds with
comparisons to modern gliders (ASW21). Worth a read.
(Originally
posted on the paraglider SFBAPA Group.)
Dave

http://www.pnas.org/cgi/reprint/104/30/12398