This condition, referred to as a “loon fallout,” occurs when the loons get weighed down by ice buildup while flying, becoming unable to remain airborne, the Raptor Education Group Inc. of Antigo, Wis., posted Thursday on its Facebook page.

“Once the ice accumulates on them, they’re no longer aerodynamic, and they fall,” Marge Gibson, founder and director of Raptor Education Group, told Wisconsin Public Radio. “They just happen to be in the wrong place.”

These iconic waterbirds of the northern forests are in danger if forced to the ground, as they have legs so far back they can’t walk on land, according to REGI.

“The current ice/rain and unstable air currents is a perfect set-up for this phenomena to occur,” REGI wrote in its Facebook post.

A FEMALE COMMON loon is cleaned off and evaluated at the Raptor Education Group Inc. facility in Antigo, Wis., after being found in a cow pen at a farm in Gleason, Wis. The bird was a little thin but had no serious injuries, REGI officials posted on their Facebook page. (Photo from Raptor Education Group Inc.)

Loons also can’t take flight unless they have a quarter-mile of open water as a runway, so may become trapped even if they make it to a pond or other small body of water, the bird rehabilitation and education group advised.

By Thursday, downed loons had been reported in Wausau, Gleason, Stratford, Neva, Rice Lake, Antigo and Drummond, all in Wisconsin, according to REGI. At least 25 loons had been rescued as of Friday.

Linda Grenzer, who operates Loon Rescue Inc. with her husband Kevin, was en route to the REGI facility in Antigo on Friday night with a loon captured in from a small pond in Curtis, Wis., after a 90-minute chase.

Three more loons had been seen on small ponds but eluded them by diving and swimming away, she said. Two others managed to take off on their own in Stratford and Wausau, Wis., from ponds that had no trees to clear.

This was the second loon the Grenzers, based in Tomahawk, Wis., had transported to REGI, and appeared to be a large male in relatively good shape, she said.

They also were the couple who picked up a female loon surrounded by curious Holsteins in a mucky cow pen in Gleason, Wis. REGI posted photos of the bird being hosed down to clean off the manure, then snapping up small fish in a tub. That bird was described as a little thin but with no serious injuries.

Anna Pidgeon, a professor of forest and wildlife ecology at the University of Wisconsin-Madison, told Gaby Vinick of WPR loons are built to swim fast and pursue fish underwater, so their legs are placed far back on their bodies.

“It’s distressing to think about loons being stuck on pavement or fields or just completely stranded and vulnerable. They’re way out of their element,” Pidgeon said.

REGI recommended that anyone who comes across a downed loon or one that appears to be trapped in a too-small body of water call REGI at 715-623-4015 or Loon Rescue at 715-966-5415 for advice before attempting to step in. Or contact a local wildlife agency. Loons are powerful birds with sharp beaks they will use for defense, they warned.

Depending on conditions, the best option might be to release the loon if enough open water is found for takeoff. If the bird needs care or to be evaluated, REGI advised: “You can cover them with a blanket to contain them. You can transport them in a Rubbermaid container with air holes in the top. Please put towels on the bottom of the container or box to cushion their V-shaped keel and prevent injury.”

A similar situation occurred at the end of April 2021, when the same Raptor Education Group reported roughly 35 phone calls about stranded loons after a late-season snow, according to an article that spring by Paul A. Smith of the Milwaukee Journal-Sentinel.