Great shots!
A quick suggestion if you don't mind, your in camera meter is setting for the ambient background light, in most of the scenes. Add a stop ( or so) in those flyers, the background will be a little over exposed, but the bird will show details that are underexposed now. The subject will be correct and you can crop the sky to minimize it's weight in the composition. I have a new laptop that I haven't calibrated yet, I will look at them on a calibrated screen in a little bit to see if it is my laptop, but I think it might make a big differnce to you.
I have a 6-8 week span here in Utah, when the migratory pattern places them in The Great Salt Lake in great numbers. Other then those winter months, they are a rarity here.
I have a few threads here, and some of my favorites here.

http://www.splash.smugmug.com/gallery/4078871_M3Wbi#248202302_i9unq

First gallery my webpage. I have been shooting these majestic creatures for a few years now, they are inspiring. Almost as good as fish.............
Enjoy em!