thanks for looking Jan and Russ.
The are indeed well camouflaged but just noticed I overlooked giving full details although of course I have posted in captive rather than wild - this was to be a full photo day using various owls from the local BOP centre but due to the weather we only got as far as shooting the tawny. The idea is to use set ups that would not look out of place in their natural habitat and this tree was chosen for that purpose. I remember being told about one at Arne RSPB a couple of years back and even when the warden pointed it out, it was still very difficult to see
Stan