Yes taken with the Canon 400mm 5.6 L, a cracking good lens.
No. 1 & 3 are full frame, No. 4 is almost full frame and number 2 the bird was middle of the frame so I cropped a bit off the top right for composition.
Well for me it's very hard, quite a few of the shots when I started were way over exposed ,especially the ones were the bird was small in the frame. So I used a bit of exposure compensation until I got them pretty close, then pulled then back a bit more in processing from RAW.