First outing with Nikon brand

First of all I'd like to thank all forum members who helped me with a very first moments with Nikon (D500 and 200-500/5.6).

Past Tuesday I finally made a trip to Bolsa Chica Ecological Reserve hoping to shoot terns in flight to test new to me (and main reason for switching the systems) fast AF and AF-C tracking.

All shots are handheld; I'm not a big fan of tripods.

Unfortunately it was not like last year when hundreds and hundreds birds, each carrying fish, were constantly flying above my head. However, That is what I came for:

Tracking was a breeze, but my unfamiliarity with D500 and whole Nikon interface took a tall, of course :-). Here another tern which I accidentally shot at f/18 (?). To hide some noise and softness (ISO got bumped to 3200) I re-processed it in B&H:

I haven't figured out yet how to optimally re-program the buttons to be able quickly shift between AF modes and AF area (primarily Spot and Group; I haven't tried the other yet).

When I was able to switch between AF-C, Group, pre-programmed M to AF-S, Spot, Av I was able to shoot a few other than terns creatures:

Long-Billed Curlew

Endengered Ridgeway's Rail who found a new home in Bolsa Chica a few years ago and started reproducing. There are about 15-20 species around now.

There is nothing special in perching osprey. However, I made a mistake (yes, another one) and badly overexposed the shot. To my surprise I was able to retrieve almost everything during simple PP manipulation. For example the throat was just blown completely. This is new to me. With Pentax I always preferred to underexpose a bit. Both cameras do have 14 bit depth, but as I see Pentax better recovers shades and Nikon (to my very limited knowledge) is good with recovering highlights. There is some strange experience: some underexposed shots with D500 came out with excessive noise even at ISO200 (?).

To make it short here you are: the local osprey:

And the last is a mammal that rain quite close to us:

In short I really liked D500 as a wildlife camera, but the learning curve is quite steep as I can see. AF-C abilities and difference from my previous experience is incredible!

I'm not still sure should I keep 200-500 though. It is really good lens. However, after shooting 500mm prime for the last 5 years, I don't not see such crispness and clarity from Nikkor. Of course, it is 4 times cheaper, and it is incredible for the price. I really like 2/3 of my usual load weigh and versatility of zoom. Another strange thing is 200-500 gets noticably softer when focused closer to infinity. Is it normal for the lens?

I'm going to shoot more technical/natural stuff to make my final decision. However, D500 is sold!:-D