Why are swans turning up dead in Utah? Experts believe the birds fell from the sky.

(Al Hartmann | Tribune file photo) Tundra swans fly over Salt Creek Waterfowl Management Area south of Tremonton in November 2017. Some Davis County residents discovered dead or injured swans in their yards and pastures after Friday night’s winter storm.

Some Bountiful and Woods Cross residents discovered dead or injured swans in their yards and pastures after Friday night’s winter storm.

Wildlife experts aren’t sure how the birds died, but they suspect it might have had something to do with the weather.

Mark Hadley, northern region outreach manager for the Utah Division of Wildlife Resources, said over 20 dead and injured swans were found in Davis and Salt Lake counties as of Saturday evening.

The injured swans have been taken to wildlife rehabilitation centers, said Hadley. The dead ones will be taken to a lab on Monday to have their cause of death determined.

One of the DWR officers who picked up the birds inspected them enough to know they weren’t shot, said Hadley.

“No one is going around shooting swans and putting them in people’s yards,” he said.

Hadley said the DWR is speculating that the deaths had to do with the weather. He said he has never seen anything like this happen to swans in more than two decades at the DWR.

Dalyn Marthaler, executive director of the Wildlife Rehabilitation Center of Northern Utah, said she hasn’t seen signs of illness in swans that were taken to the center. The injuries the swans have suffered, broken legs and wings, are consistent with having fallen from the sky.

People reported seeing lighting, rain and hail on Friday night, said Marthaler. She said Utah is a major pathway for migration. It is not uncommon for birds to migrate at night guided by the stars. Marthaler said it is too soon to know for sure, but the birds may have been caught up in the storm and pushed out of the air while migrating.

Although such a fate is unusual, it is not entirely unprecedented. Several years ago there was a storm in Dugway that pushed down and killed over a thousand grebes, Marthaler said. She said some injured grebes were taken to the center on Saturday, although there were more injured swans.