Black-Capped Crossbill? I Don’t Think So!

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Published on December 8th, 2010  |  Discuss This Article  

Numerous recent press reports are calling attention to an ongoing avian disease mystery in Alaska and the Pacific Northwest: an outbreak of beak deformities, more formally known as avian keratin disorder. The USGS and U.S. Fish and Wildlife Service recently published an analysis of this intriguing and mysterious disease.

These beak deformities, some of which are very profound, cause great problems for the individual birds. They have difficulty feeding, if they can feed at all. They cannot preen their feathers, which means an accumulation of dirt and parasites and a loss of insulating function. Due to the difficulty feeding, they may spend more time feeding and risk greater exposure to predators. All of these would invariably seem to lead to a shorter life span.

They have now found evidence of beak deformities in 30 different species of birds, with the highest number of reports for Black-Capped Chickadee. Other species with multiple reports of beak deformities (in Alaska) include Northwestern Crow, Red-Breasted Nuthatch, Black-Billed Magpie, Steller’s Jay, and Downy Woodpecker (species listed in descending order of number of reports). While some birds have relatively minor deformities (hence my joking reference to a crossbill in the title), other birds’ beaks are severely malformed and distressing to look at.

The researchers have not yet been able to pin down an exact cause for this problem. The incidence of deformities is much higher in adult birds in both chickadees and crows, suggesting that this is something that develops over time after hatching. Another piece of evidence supporting this is that the research team found many cases of marked birds which had normal beaks upon first capture, but abnormal beaks upon a subsequent re-capture. Possible explanations, which remain to be tested, include a fungal, bacterial, or viral infection; parasites; malnutrition; or a chemical which affects proteins involved in beak development.

The researchers, who recently published their work in the ornithological journal The Auk, did a detailed analysis of the data on the Chickadee. By soliciting information from other scientists and the public, they found a total of 2,191 Black-Capped Chickadees with beak deformities in North America between 1986 and 2009. Of these, a whopping 98.6% of the records came from Alaska, which appears to be the epicenter of the disease outbreak. Similar surveys by a subset of the same research team for deformities in the Northwestern Crow also show a major concentration of cases in Alaska, but also many cases from the Puget Sound area of southern British Columbia and northwest Washington.  The latter zone is an area of overlap between the Northwestern and American Crow, so it was not possible to definitely identify the species involved in that area.

This mystery requires urgent and dedicated attention before avian keratin disorder spreads further across North America.

(Image: A Black-capped Chickadee with a beak deformity. Image Credit: Photo by Robert Gill, Jr.)

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5 Responses to “Black-Capped Crossbill? I Don’t Think So!”

  1. Donna says:

    I’ve noticed two magpies that feed in my yard have crossed beaks. I asumed it was genetic as a couple of magpies ( a parent and it’s young have a drooped wing. I’ll be paying more attention and going over photographs to see if I see one with it’s beeak chaanging.

    I live in Edmonton Alberta

  2. Alison Kerr says:

    The little chickadee pictured here makes me sad. What’s more important to a bird than its beak? If I see any in my area I will be sure to report them.

  3. Ginny says:

    We had a rufous hummer in 2003 that developed a deformed beak after being in our yard for 3 months. I wonder if that was the same disease? We couldn’t find anybody interested in taking the carcus to study it at the time.

  4. Don Smith says:

    In domesticated parrots this sort of beak deformity is caused by malnutrition(generally when infants), chemical exposure, and diease. If caught soon enough when small it can be fixed with break manipulation with fingers and or surgrey. Sometimes its permanent. Its heart breaking if you ask me. Slow painful death! If the beak deformity is human caused then shame on us!

  5. Anne says:

    I have a Mourning Dove with upper mandible extending downward and the lower mandible curves upward to the side. The length is not as extreme as this BC Chickadee. This dove has been with us over 1 month now. It is easier for it to feed on sunflower seed placed in a dish as seed in the snow gathers on the bill which it then has to scratch off.It is very aggressive when another dove approaches its dish. It is very co-operative for photos.

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