Drying the wings and baking-off bacteria are also
possibilities. This posture is termed the
"horaltic pose".
It's the HERALDIC pose, because it looks like on a coat of arms.
This is one of the cases where it _helps_ to _not_ be a native speaker of
English if you want to spell it right. <sigh>
Vultures are related to storks, right?
New World vultures were long thought to be related to storks based on, like,
four or five morphological and behavioral characters. But every single
molecular phylogeny has found them as the sister-group of most or all of the
traditional falconiforms. The great mystery are not the New World vultures,
but the falcons, which are sometimes found far away...!
(The Old World vultures are of course just eagles/hawks that went lazy. That
has never been doubted.)