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Birds with Deformed Beaks.

October 3, 2015

I noticed something odd the last couple of weeks.

Readers of this blog know that I feed birds and squirrels out in front of my apartment.  A flock of a dozen or so House Sparrows drops by for the occasional bite.  But something funny caught my eye.

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Here’s what a typical (female) House Sparrow looks like.  Notice the beak, which is short and robust, good for cracking seeds.

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Now look at this young male House Sparrow that hangs around my apartment.  His upper mandible is very long.

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Here’s a female hanging out too- her upper mandible is longer and the tip is curved slightly down over her bottom mandible.  It almost looks like another bird species’ beak.

So, 2 out of over a dozen sparrows have beak issues.  I’d never noticed this before, though you do have to look somewhat closely at them.

What is going on here?

These are examples of avian keratin disorder.

(USGS Alaska Science Center)

Sometimes birders observe birds with odd-looking beaks. Numerous Black-capped Chickadees with greatly elongated and down-curved upper beaks were reported in 1998-1999 in southern Alaska, for instance. Scientists studying this phenomenon have yet to determine a specific cause. Bird beaks are much like human fingernails—soft structures that actually grow at a constant rate all the time. Many factors have been implicated in causing birds’ beaks to grow abnormally, including structural damage to the beak, disease, parasites, nutritional deficiencies, genetic defects, exposure to extreme heat, and exposure to environmental contaminants.

A slight malformation may not affect a bird’s survival, but an extreme deformity may make normal feeding difficult if not impossible.

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At first I thought something was stuck to this bird’s beak- but unfortunately it is a deformity.

In the Pacific Northwest and Alaska several years ago, an increasing number of beak deformities were noted- the cause is still unknown.

“You see them feeding, and it looks like they shouldn’t live for more than a couple of days,” says Van Hemert, a University of Alaska graduate student and USGS employee. And yet they do: aided by food at bird feeders, some afflicted chickadees have survived for more than a year with overgrown bills. The scientists have even seen the bills grow so long that the elongated portions snap off, temporarily returning the bird to a normal appearance before it regrows.

Preening is also a problem. “They can’t access their preen gland as easily, and that reduces their ability to waterproof their feathers,” Van Hemert says. “A lot of the birds we catch are incredibly dirty, greasy, almost black.”

…The scientists have estimated the prevalence of what they now call “avian keratin disorder” (other body parts such as claws, feathers, and leg scales sometimes show abnormalities as well). Across a broad swath of coastal and interior Alaska, an average of 6.5 percent of Black-capped Chickadees show deformities. Across a smaller range of six sites (nevertheless spanning 550 miles), an average of 16.7 percent of Northwestern Crows were affected.

If those percentages sound high, they are—other deformity spikes, including cormorants affected by organochlorines and selenium in the Great Lakes during the 1970s and ’80s, topped out at about 3.3 percent.

“Everything hints at environmental contamination,” Van Hemert said. Birds don’t show symptoms until they’re adults, reducing the likelihood it’s a genetic disorder, and chickadees don’t disperse far, discounting the possibility that it’s a disease.

But the cases are spread across such a wide area, including some fairly unspoiled places, that it’s hard to identify a likely contaminant. Van Hemert now wonders if two disparate factors could be working together. She has shifted her attention from ecological patterns of the disorder and begun studying what goes wrong in the keratin-producing cells, hoping that will point toward the cause.

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This bird seems to be able to eat well enough, despite the beak.  Since he is a young male, I wonder if this is a birth defect- since the birds out in the Northwest were adults when this happened.  Its sad to see this, but the bird has adapted well to its beak.

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It takes a bit longer for him to manipulate his food to eat, but so far he’s doing alright.

I wonder if these 2 birds with beak issues are from the same nest?  There are many possible causes for this condition, but seeing 2 at the same time- when before I noticed none- makes me think its a possible birth defect, perhaps from the same parents.  But its hard to draw a conclusion for certain.

I’ll keep an eye out for these birds and let you know how things go.

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6 Comments leave one →
  1. October 4, 2015 7:21 am

    It’s distressing to see these deformities, but as you point out they seem to be coping with them. I do hope it is just a natural variation in genetics and not the results of environmental contamination in your particular area. Very interesting!

  2. October 4, 2015 3:32 pm

    I’ll be interested to hear if you learn anything more. Meanwhile I’m going to be paying closer attention when I look at the birds in our yard.

    • October 4, 2015 9:58 pm

      I was really surprised to see this, Robert & Donna! At first I thought something was stuck to the young male’s beak but no…hope he makes it.

  3. October 27, 2015 7:25 am

    Oh how sad. Made me think of the pictures of extra-legged frogs. 😦

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