Pigeon racers say scores of their birds are mysteriously vanishing in what some claim is Britain's bird equivalent of the Bermuda Triangle.
Fanciers say they are experiencing "disastrous" and unprecedented losses in an area between North Yorkshire and Country Durham.
In one recent event, only 13 of the 232 birds released in the region made it home to Scotland.
And 200 failed to show up after 1,000 were released over the Triangle, which spans from Wetherby near Leeds to Consett, Co Durham.
Keith Simpson, of the East Cleveland Federation of pigeon fanciers, said: "They're calling it the Bermuda Triangle but who knows where they are going?
"Last weekend a mate had 63 birds away from Durham and 25 went missing.
"It's heartbreaking, it's puzzling and some people's seasons are finished because of this."
He said his club also got reports of 24 dead birds on a North Sea oil rig 40 miles off the Yorkshire coast.
Mr Simpson added that it was impossible to say why flocks were going AWOL, but it could be down to freak weather patterns in the area or a mystery illness.
Racing pigeons can be identified by a tag on their leg and racing clubs often organise couriers to pick up lost birds and return them to their owners. Details of how members of the public can report a lost homing pigeon can be found at www.homingpigeons.co.uk.