I go into Haigh Hall woodlands and watch the local Tawny Owls coming out of their roosts sometimes, watched a pair last week and they were silent but I left before it got really dark, Raptor workers recommend listening in an area for up to two hours after sunset to check for territorial occupancy for most Owl species and claim that clear moonless nights are best. Tape playbacks also work well with Tawny Owls.

I also go and listen for young Tawnys in early/mid May, it doesnt half sharpen your senses walking in woodland after dark, couple of years back I was straining to listen for the young Owls hardly daring to breath when a Dog Fox let out a bark about twenty feet away from me, I nearly jumped out of my skin, sometimes best to pack a defibrillator and clean underwear when going listening for Owls

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We have a dark farm track walk to & from our local pub Jeff and a couple of weeks a go we were regularly hearing Tawny Owls as we wended our way home. The timing was probably a good hour to two hours after dusk, it had got completely dark by then and they were calling non-stop. Now the day length has increased we are walking back at dusk & in the half-light and no calls at all, so agree early evening does not seem to be the best time.