There's nothing more rewarding then Photographing wild Owls, ive sat and watched them for years on the Humberbank, across fields in East Yorkshire and up on the moors of North Yorkshire.
Ive learnt allot from my mistakes over that time, heres a few tips, you dont need to get low down and totally hidden in your ghillie suit, just hide your outline, for example if your walking along the river bank and you spot an Owl tracking your way, move down until your heads a metre below the bank level, that way you can still enjoy good uninterrupted views without vegetation getting in the way. Ive had Short Eared Owls float past me about a meter away.
Next seanario, ever been out for a walk and several times youve seen a Barn Owl hunting the same area, do yourself a favour and buy a bag hide, these simple throw-over hides are fantastic to blend in (bought mine for Wildlife Watching Supplies). Ive got very close to Barn Owls using them. Depending on how close the Owls move remember to use silent shutter, the Nikon D810 is fantastic at keeping the noise down to a minimum, wait till there as close as possible then fire your shutter, although the downside is slow shutter speeds the upside is the Owl hangs around allot longer. If you want to increase the chances of the Owl staying longer you have to be really switched on, if as your taking your shots the owl suddenly looks directly at you, chances are hes heard your shutter clicking, its either time to get a few last shots and take a break, or freeze all your actions and remain absolutely motionless for 20 seconds until his concentration is back on the mice. If needed only reposition when hes totally out of view.
All birds love a good perch, so if the fields there hunting over has a distinct lack of perches, find a nice looking post and set it up in a good location, remembering to position for light. Ive had some great photos of post birds, there of course very random shots.