LOL True. My lenses are in the drybox and longing to come out for some action. Been too busy with other things. Have not taken holidays too.
Yeah, from what I read, the Tamron has slower focus but image quality is not bad.
For that purpose, the new AF-S 80-400mm VR is excellent.
The 70-200mm f/4 Nikon is a very good lens. But if you want something longer, you may want to use a 1.4x TC on it but that's about the max it can take.
If you can get the AF-S 300mm f/4 2nd hand, you get more reach and because it's a prime, you can use up to 1.7x TC with decent results because the bare lens itself is razor sharp. This is a go to lens for beginner / aspiring birders. The downside of this lens is that it's not a zoom lens and it does not have VR for hand holding.
Anyway, you'd notice that if you go deeper into birding photography, weight is inevitable and you start to buy a tripod for good support and stability. Hope you get a little bit of the whole picture because it will be more and more expensive.
Some people have opted with digiscoping because they desperately need the long reach focal length the setup gives. They are quite expensive too but you get quite a good reach and focal length with moderate weight setup. The other way to get good reach with light weight is to go with a Nikon 1 body, FT1 adapter and a lens like the AF-S 300mm f/4. That setup would give you a field of view equivalent to a 810mm lens.

Some people also use the AF-S 80-400mm VR and get equivalent 1080mm field of view and still get VR. You can choose the cheaper 10Mp J1 or can opt for the newer 14Mp AW1 bodies. The electronic shutter available is actually very useful when shooting long focal lengths and it eliminates shutter vibration usually associated with mechanical shutter on DSLRs.
Aiyoh... Why have to take photo with the guy? Spoil lah.

I prefer the series with her solo.
I think the model is also a crucial part of the equation.