Bird with 100-400L
this pic already is a heavy crop and PP++
Yeah, not much you can do when they're that far away.
Even with IS and 1/1000s exposure it seemed very difficult to get a really sharp pic,
For in-flight shots I'd recommend turning the IS off. 1/1000 is pretty marginal too.
Hope you spot them again (close by),
Good judgment comes from experience.
Experience comes from bad judgment.