Nikon 500mm f/4 VR or ?

Yes we like super-telephotos. But it is up to you. There is a lot of satisfaction from shooting hand held and from being more mobile with lighter slower lenses. I sometimes shoot with a 2.8 70-200 but honestly in good light a 70-300 is very hard to discern the difference. I consider Bifs a sport and I will try for them with anything, just for practice, including a travel cam. Also I admire guidnets efforts to take the best lens possible (on an inflatable boat) and then try to get closer.

Maybe learn when and where they head in the evening to roost. You can be within a few yards and get golden light besides. Position yourself to avoid back-light and difficult backgrounds. Enjoy being out there knowing sooner or later you will get that damned Kingfisher and enjoy that skirmish between the Eagle and the Osprey even if it is out of range this time. BTW I don't have a tripod and I suppose my pictures show it but I have some great days. 

Onstar equipped