They drift over the fields like ghosts as the sun sinks, scanning the ground below for their prey.
As night falls, silent hunters are on the prowl over rural Norfolk.
But as the barn owls take to their wings over the countryside, they are being stalked by wildlife photographer Les Bunyan.
A barn owl about to swoop on its prey (Image: Les Bunyan)
Mr Bunyan, 67, from Snettisham, spends hours observing the nocturnal hunters as they search for mice and field voles.
He uses a long telephoto lens on his camera, so he can focus on his subject matter from a distance without alarming it.
For, although barn owls are apex predators at the top of the food chain, they are also easily spooked.
A barn owl takes a breather on a fence post before resuming its nightly hunt for prey (Image: Les Bunyan)
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"I always keep my distance but on occasions, after standing stilll for a long time, the owl will come close and perch on a post," said Mr Bunyan.
"The bird's well-being is always the most important thing, so if I think I am affecting their behaviour I leave, there's always another day."
The birds are nicknamed ghost owls because of their white plumage. Another moniker is screech owl, because of their piercing calls.
A barn owl on the wing over Norfolk (Image: Les Bunyan)
The owls' hunting flights will soon become more urgent as the breeding season brings more beaks to fill.
Yet their chicks' arrival comes just as rodents have their first young of the year, meaning a ready food supply.
Barn owls are not Mr Bunyan's only target. The retired joiner, a keen naturalist, has become renowned for his wildlife pictures since he moved to Snettisham nine years ago.
A barn owl on the hunt for prey (Image: Les Bunyan)
"My photography goes in cycles," he said. "At the beginning of the year owls and hares are my main focus, then as spring takes hold, things like marsh harriers and warblers become interesting.
"Summer brings late evening barn owl chicks fledging and then the autumn wader spectacles on The Wash."
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