From my roof top

I am trying to choose between the 300F/4IS and the 400F/5.6NonIS for my 550D and I am testing borrowed ones now. I borrowed a 400 today and tested it on my roof top. The photos are ugly because they were taken between 5.30 and 6.30 pm and the lens does not have IS so I had to bump the ISO to 800 and I was not able to get good compositions.
The fact that my skills still have a long way to go is actually the main contribution to the bad exposures but I just wanted to share photos of what I can see from my roof top. And these are just a few. It is an apartment building so I can't build a feeder, these guys roam about here on their own.
Please CnC, thank you.

These are pretty good..the last being my favorite. It would be nice if you could identify each of the birds as you post them.

Your shots are good. The first five look like backlit subjects to me (i.e. taking the shot more towards the light rather than the light behind you shining on the subject). In that case you need to dial in EC to light up the subject and usually also to adjust the exposure pp to bring up shadow detail and reduce highlights. Also try spot metering rather than evaluative (which will meter for the subject rather than the surroundings)
In terms of the lenses, both are good (I have both) the pros and cons have been covered many times by myself and others (do a search you'll find the topics) and I can't really add any more to what I've said in the past.
So your technique looks good, a bit of work in PS (LR is even better for this) and you'll get fine results