kXnPunk - "3D app"? This isn't CGI, these are real puppets shot with a real camera. I'm new-old school, I can't be happy sitting at a desk pushing buttons and sliding a mouse around all day... my creatures need to be real.
The main difference between the way stop motion used to look and the way it looks now is how it's composited with motion blurs, atmosphere and any of the other things that can be added for believability in post production. Computer technology threatened stop motion animation with extinction a decade ago... now it's being used for it's revival!
Here's another look at those birds. The same footage is used over several times to show how versatile the post production process can be in adapting the puppets into new environments... http://www.youtube.com/watch?v=AN2Op5PaIBg