Drogoz's tail and horns are included in his hitbox so if he's far away, aim a just little higher than normal. This will prove helpful since you can shoot him once while he's not looking, and if he decides to ascend, you'll be able to catch him.
Willo's hitbox is very large and she's slow so you have the advantage if you're able to aim for her wings. If she decides to fly away from her original location, don't track her, predict where the arch will slow down at its peak and shoot there.
When Strix goes into stealth, he's fairly loud, allowing you to be able to more accurately predict where they will be. Strix usually hides and peeks to shoot, but shoot once, teleport mid-long range, and he's toast after the second shot.