June 28 (UPI) -- Residents of a Norwegian condominium building said swallows are nesting inside their parking garage after mastering the technique of opening the door.
The residents of the building in Tonsberg said swallows used to follow their cars through the garage doors so they could build nests away from predators, but the birds have now mastered the art of opening the doors themselves.
Ulf Bottolfs Andersen, chairman of the condo association, said the swallows have learned to follow a specific flight path that takes them past the motion detectors that control the garage doors. He said the birds follow the same path every time and have been seen operating the door on their own more than 100 times.
Ornithologist Ragnar Syvertsen said he was surprised when he viewed footage of the swallows opening the door.
"This I have not seen before," he told NRK. "There is no doubt that the barn swallows have learned this on their own over a period of time."
The Norwegian Ornithological Society said barn swallows are well known to prefer indoor areas for nesting, but the behavior of the Tonsberg swallows is highly unusual.
"Swallows are just so cool! Barn swallows build their nests in buildings, mostly barns. In Tonsberg, a family has settled in a parking garage, and has their own way to fly in and out through the gate," the society said in a Facebook post.
Andersen said officials are considering adjusting the sensitivity of the sensors to prevent the birds from operating the doors on their own.