Nice work Alan and Jack!
Alan, the zebra dove is the most impressive from the standpoint of resolution combined with long focal length. The 600mm shot below that post, is the weakest example of resolution...it's quite soft. The lens can possibly do better I suppose, but how much better at 600mm?
It seems to me the lens is the most impressive below 450mm, which is not unusual.
I forgot to notice, were all of these hand-held, or was it a tripod, monopod, or other support?