these were on a d500 and a last gen sigma 120-300, the one before the sport introduced. AF-C and typically D25 or GRP.
as its not my main genre i find getting the right autofocus settings the most difficult. I dont do it enough to be able to compare keeper rates and sometimes it will be pot luck, especially in low winds, if the bird comes flying towards you or leaves the pond at 90 deg to your shooting. Spray and pray does come into it but then again if i look at a sequence of 10 1/2000s shots at 10fps there is a chunk of pray as to where the wings are, the speed of movement of these is fantastic. I just wish i had the confidence/rigour to release the back button and reacquire but i dont see enough dives to let go. Might be different if there was a timetable and you knew another would be along soon.