Not Sharing!

We had a huge snowstorm today and the birds were all over the feeders. The cardinals were extra fun to watch. This one got territorial on the suet feeder against a downy woodpecker. The woodpecker was NOT backing down. The cardinal eventually gave in. 
The extra is of a female cardinal all puffed out in the cold.
I used my 200 - 500 D series lens with the ftz converter. The max aperture is 5.6. The low light from the snowstorm called for a high ISO. I think that I might have figured out why this lens has not worked well for me, I need to shoot in brighter light. When the weather clears, I will test my theory.