This image is made up of the same bird I shot in sequence and then placed in formation. I tweaked some features(very minor amount} to look like different birds.
It looks very believable, Dave, nice job. A very slight vertical gradient in the BKGR might be worth a try. Also, selective lightening the underwing of the top bird to make the bill more contrasty might help. Nice composite!
Dave, Nice work with the composite and I like the subtle changes you did to the bird. I see some compression in the BG. A bit tight but it is well designed and I like it.
Based on a few comments I changed the backround adding a graduated effect and lightening the blue. Excuse some errors since I did it quickly. Not sure if I like it better or not...
Like the lighter BKGR much better, Dave, and you eliminated the posterization. As for the gradient, you're getting there but I think maybe you overdid it - the change seems too abrupt toward bottom. Try making the gradient not quite as light at the bottom but still lighter than the top.