How (not) to drown owl:
"Owls have very soft feathers, which helps to give them silent flight. Unfortunately, the down side to this is that they absorb water like a sponge and so if they fall into water troughs or similar deep water containers, unless they can get straight back out, they will become waterlogged and will drown. You can help them by keeping these containers empty near nest sites, or by floating a bread tray or similar raft on the water. This will give the owl a chance of clawing back out if it falls in".