Friday, November 12, 2010

Gnarley Beaks

Chickadee- USGS Photo
Avian Keratin Disorder

Mysterious new disorders in wildlife are always worrisome signs of possible pollution or other human impacts on wildlife.  Some like white nose syndrome signal a new infectious disease.  Others like the thinning of egg shells in birds of prey and waterfowl have led to the banning of DDT, an action which may have contributed to the comeback of the bald eagle.

A new troubling finding called Avian Keratin Disorder is cropping up in the Arctic.  There is a rising incidence of beak disorders in Alaska and the Pacific northwest.  Initially noted in a few crows, it is now estimated to occur in 17% of the coastal Alaska crow population.  Now it is found in 6.5 percent of adult black-capped chickadees in Alaska.
"The keratin layer of the beak becomes overgrown, resulting in elongated and often crossed beaks. The deformity showed up in adults birds, most often in the upper beak but sometimes in the lower beak or both.  The abnormality sometimes is accompanied by elongated claws, abnormal skin or variations in feather color." *
Nuthatches and woodpeckers have lately been seen with beak distortions as well.  They all have in common the tendency to live year round in the area, but they have totally different food sources and habitats.  These factors suggest that the disorder is spreading.

The cause is unknown with theories including infection, nutritional deficiencies and pollution as factors.  Similar problems have been associated with environmental pollutants such as organochlorines in the Great Lakes region and selenium from agricultural runoff in California.  There should be more information as awareness of the condition increases.

*This story as reported in the Los Angeles Times.    The study is available in abstract in Auk, a Quarterly Journal of Ornithology.
Lisa Berger provided a 2007 resource that has a much deeper look at the disorder.  Download this pdf   

1 comment:

  1. I recall seeing at least 3 different species visiting my backyard (Springfield, MO) feeders more than 20 years ago that showed beak deformities. Carolina Chickadee, Downy Woodpecker, and Carolina Wren were the resident species represented. An article in ABA's Birding discussed this in 2007. Copy and paste the URL to your browser to learn more: http://www.aba.org/birding/v39n5p48.pdf
    Interesting Stuff--Lisa Berger

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