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Beak disorder baffles scientists

Chemicals and disease may be cause, but solid evidence is elusive

Posted: Sunday, June 22, 2008

You may have seen one of Caroline Van Hemert's research subjects at the Auke Bay Hot Bite, where he is a regular customer. He wears little ankle bands and appears to subsist on French fries, breakfast burritos, bits of hamburger, ketchup packets and sundry delicacies from the trash.

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Brian Wallace / Juneau Empire
Brian Wallace / Juneau Empire

Unlike the straight peck-peck-peck of most birds, this crow leans his head sideways to pick bits up off the ground.

"It's amazing how well they do, considering how grossly deformed their beaks are," said Van Hemert, a graduate student at the University of Alaska Southeast and a wildlife biologist for the U.S. Geological Survey who has studied beak deformities in northwestern crows for the last four years.

Crows, chickadees, nuthatches, woodpeckers, magpies, jays and other year-round Alaska resident birds appear to have unusually high proportions of beak deformities. For chickadees, the longest-studied species, the number is about 10 percent of adults. A normal proportion might be around ½ percent, Van Hemert said.

The numbers seem to be rising. And the reports, initially thought to be a local problem, are now coming from all over the Pacific Northwest.

"Whatever's happening is pretty bizarre," she said. "It's pretty clear that something has gone wrong."

So far, researchers are baffled as to what that is.

Colleen Handel, principal beak-deformity researcher at the USGS Alaska Science Center in Anchorage, started in 1999 looking into reports of black-capped chickadees in Anchorage with strange-looking beaks. The beaks varied a lot. They were often curved so the beak parts didn't meet, sometimes longer than the birds' bodies. Since then, she has identified nearly 2,000 deformed birds.

Beaks are made of keratin, a protein also found in human hair and fingernails. They grow continuously and are worn down in the course of ordinary feeding. But with a deformed beak, a bird like the Hot Bite crow may stop wearing down the beak, so it gets longer and longer. Van Hemert suspects the deformity might also involve some accelerated beak growth.

The cluster of deformities here is troubling partly because crows are so different ecologically from chickadees. Both are year-round residents, not migratory, that tend to hand out in urban areas. But chickadees specialize in seeds and insects, while crows are omnivorous and tend to eat things like mussels and other intertidal invertebrates.

The USGS researchers have struck out looking for parasites, disease or contaminants that correlate with the deformities. They don't think it's a genetic problem, partly because the deformities don't show up until adulthood.

The research has led to more questions than answers, especially as the geographic range of the deformity cluster has expanded.

"I think it's really fascinating. It's frustrating at times," said Van Hemert.

The birds are particularly hard to test. For one thing, chickadees are so tiny that you'd need a sample practically the size of their whole body to get a good tissue sample for testing. That makes the crow research promising, since those birds are so much bigger. Still, a lot of unknowns remain. Nobody knows what normal background levels of contaminants are. Or what all the different contaminants might be. Or how the chemicals interact with each other.

There have been a few related studies, but none has shed considerable light on the Alaska situation. In one the deformity was linked to high selenium levels, but the deformity was a necrosis rather than the overbite seen in Alaska birds. PCBs, a class of industrial organic chemicals called polychlorinated biphenyls, were tentatively linked to deformities in the Great Lakes. None of these populations had the high proportion of deformity found in Alaska, though, Van Hemert said.

In the last year she has trapped 130 crows, including 30 in Juneau and 37 in Haines.

Chickadees are easier to trap. They're either interested in the food or they're not.

"With the crows, they require a little bit of psychological persuasion. They're so smart - you have to come up with ways to convince them the food is worth the potential risk," Van Hemert said.

One version of a trap is a PVC frame with a net strung across the top. A bird has to be willing to walk under it to get the food, and then a researcher drops the net on top of it.

That only works once.

So the other trap she uses is called a "whoosh net." The bird walks over to the food, which is next to the net; a human releases a mechanism and the whole bungee-loaded thing flies up and over the bird.

Once they're caught, it's not too hard to measure and band them. Although there is a slight danger of what Van Hemert calls "the pinch and twist."

"They definitely bite, but they very rarely take a chunk out of you," she said.

The research has been helped tremendously by the public, which apparently keeps pretty good tabs on its bird populations. The USGS team has gotten about 2,000 reports of deformed birds since the chickadee project began, and Van Hemert said it's not unusual to get 10 reports in one day.

"It doesn't take a huge amount of knowledge to know that it doesn't look normal," she said.

Most of the time the birds are feisty and seem healthy. Van Hemert did find one bird in Valdez who had apparently been the subject of a layman's mark-recapture study. It was covered in red paint.

"I would definitely discourage people from doing that kind of study," she said.

• Contact reporter Kate Golden at 523-2276 or kate.golden@juneauempire.com.



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