By Craig Sailor

The News Tribune

A mysterious ailment that has killed or paralyzed sea gulls around the Port of Tacoma this week is baffling wildlife biologists.

About 50 sea gulls have been found dead or paralyzed from the neck down.

“We have never seen a situation like that,” said state Department of Fish and Wildlife biologist Michelle Tirhi. “It was a mystery to our biologists and veterinarians.”

Ill birds have been found in a seated position with only their heads moving.

“One could walk up to them and pick them up,” Tirhi said. “They can’t fly, they can’t walk, they can’t move.”

Port workers began finding dead and sick gulls Sunday night.

“By the time they got to work on the 23rd they were finding more dead and sick birds,” Tirhi said. “Ground zero for this mortality event was Port of Tacoma.”

Ill birds were found at three shipping terminals and other points around Commencement Bay, including Ruston Way, Browns Point, Point Defiance Park and as far north as Kent and Redondo Beach, according to Tirhi.

The mass die-off is affecting only glaucous gulls — the common sea gull.

“This is the thing that’s odd to us, they’re only gulls,” Wildlife spokeswoman Madonna Luers said of the fatalities.

Though other species, including crows and ducks, wing around the port, there have been no reports of other species affected. That could mean the gulls ate something that is causing the illness, Tirhi said.

“Perhaps no other species was attracted to it,” Tirhi said.

What that might have been is unknown.

Port of Tacoma spokeswoman Tara Mattina said there have been no recent contaminations.

“I can confirm that there was no spill of any sort,” she said.

Tirhi said the sick and ill birds were clean.

“They have no odor or anything discernible on their body,” she said.

Toxicology testing has ruled out lead poisoning and other heavy metals.

Sick birds are still being found. On Friday, Wildlife agency biologist Emily Butler picked up a sick gull at Owen Beach in Point Defiance Park.

It will join 19 others at PAWS Wildlife Center, an animal rehabilitation center in Lynnwood.

Staff members at PAWS have been nursing the birds back to health.

“A number of the gulls had significant breathing difficulties on arrival but have since stabilized with oxygen therapy,” said Dr. Bethany Groves, a wildlife veterinarian at PAWS.

No evidence of trauma has been found.

While some gulls are thin, others have a healthy body condition. That indicates a sudden onset of illness, Groves said.

“All of the gulls are undergoing intensive rehydration efforts, nutritional support and parasite treatment, in addition to daily veterinary exams and bloodwork,” she said.

Groves has seen mild improvements in strength but she couldn’t say whether the birds will fully recover.

Larus hyperboreus, the glaucous gull, is a large white and gray gull. Juvenile gulls are more likely to be all gray, according to the Cornell Lab of Ornithology.

The gulls have yellow bills with a distinctive red spot on the lower mandible. They breed in Arctic regions but travel as far south as California.

The Tacoma bird deaths are not the only mass avian die-off in the state.

An outbreak of avian cholera has killed about 500 birds in the past week at McNary National Wildlife Refuge along the Columbia River, just downstream from the Tri-Cities.

“At this point there seems to be no connection to that mortality event,” Tirhi said.

Further test results on the Tacoma gulls will come in next week. Until then, “It’s a complete mystery to us,” Tirhi said.

Craig Sailor: 253-597-8541, @crsailor