Adobe's John Nack posted a tip in his blog that looks like a real boon for bird photographers. It seems that Photoshop CS3 and CS4 allow one to do mirror cloning quite easily. The example used was repairing an ear but it would work just as well for repairing a wing. A quote is below. Read the entire message at http://blogs.adobe.com/jnack/2009/06...er_mirror.html
He said "Open up the Clone Source panel, then specify a negative number for the width value (e.g. just put a minus sign in front of the “100”). Now Photoshop will flip the source data so that you can clone a mirror image. You can also use the panel to scale & rotate source data without having to select/copy/paste/transform it. This all works with the Healing Brush as well."
A Russ Brown video is available on the blog to demonstrate this technique.