Virus linked to beak deformities in birds

Condition occurring more than 10 times what is expected in a wild bird population

Biologist Colleen Handel saw her first black-capped chickadee with the heartrending disorder in 1998.

The tiny birds showed up at bird feeders in Alaska’s largest city with freakishly long beaks. Some beaks looked like sprung scissors, unable to come together at the tips.

Others curved like crossed sickles. Handel, a US Geological Survey bird specialist, was sure the cause of avian keratin disorder would be found quickly: contaminated birdseed, a poison targeting spruce bark beetles, maybe some sort of bacterium or fungus.

Years went by. She found herself losing sleep over a mysterious ailment afflicting 6.5 per cent of south central Alaska’s black-capped chickadees and 17 per cent of the area’s northwestern crows, more than 10 times what is normally expected in a wild bird population. Distorted beaks were spotted in lesser numbers of jays, woodpeckers and nuthatches — 24 species in all.

Eighteen years later, after many possible causes were ruled out, Handel and other scientists from California and Alaska who tested beaks of affected birds found a previously unknown virus in every one.

“It’s the strongest lead that we’ve got so far,” Handel said.

Researchers are careful to say the virus — named Poecivirus after the black-capped chickadee genus — has not yet been nailed down as the cause of distorted beaks.

To validate their findings, scientists will grow the live virus in laboratory conditions. They also will work to determine whether the virus is in other bird species.