Thanks to all of you for the nice comments and compliments, really appreciated
And yes I really have to shoot more often, I was really rusty in the beginning as I haven't shot action like BIF in ages and was more accustomed to the Sony menus and buttons after 5 years of using the a7 platform but the guys were very helpful in getting me back on track.
Embarrassingly enough I had ask Rob how to setup the AF of the D500 for BIF while in the old days I used to write "how to setup your Nikon Dxx" guides and when Sar mentioned he was shooting in manual exposure mode while I was still struggling in aperture mode a little voice in my head sad something like "of course dumbass"
But with the proper AF modes finally dialed in and using manual exposure mode with centre metering, auto ISO and an -0.7EV correction for the white birds I was finally getting sharp and well exposed birds in flight so by the time I encountered the pelicans it was a simple track the bird and release the shutter exercise