Chickadee with deformed bill the first spotted in Alberta
A rare chickadee with a deformed bill has been spotted in southern Alberta.
The bird, whose upper bill curves down and crosses over its lower bill, is believed to be the first of its type seen in Alberta, says naturalist Brian Keating.
The chickadee was spotted in Ray McKay's backyard in Cochrane, where it sat underneath the bird feeder waiting for crumbs to land at its feet, Keating said. Then the bird used its foot to brush the food into its mouth.
Noticing the chickadee was having trouble feeding itself, McKay shelled some sunflower seeds for it to feed on.
Keating said the cause of the deformity is still under investigation, but may be related to a number of factors including injury, disease, parasites, nutritional deficiencies, a genetic defect or exposure to some kind of contaminant.
Similar birds studied in Alaska
In Alaska, biologist Colleen Handel has been examining the causes behind beak deformations for more than 20 years. In that time, she has identified 28 different species of birds, both year-round residents and migratory animals, with a similar abnormality to that spotted in the Cochrane chickadee.
Of the birds surveyed, more than 1,400 were identified to be chickadees with deformed bills.
What's interesting, Keating said, is that all of the migratory birds found with bent beaks in that study were juveniles, implying they had not yet left Alaska.
Handel's team also captured and banded more than 2,000 chickadees, allowing the scientists to monitor them over a longer period of time.
When recaptured, some of the chickadees that had been born with normal bills were found to have developed deformities later in life. In one case, a chickadee's bill became deformed before it was six months old.
Looking for answers
While no clear cause for the change in bill shape is known, Keating said scientists are investigating the cause of the abnormality in several ways, including monitoring nesting chickadees and testing blood and DNA samples for possible contaminants, and monitoring nests where one or both of the adults have a deformed bill to determine whether the trait is passed on to offspring.
So far, no evidence has been found that the chicks of deformed bill parents carry the same trait. However, since chickadees are known to tend the eggs laid by other individuals, a genetic influence cannot be fully ruled out, Keating added.
Scientists are also looking into the possibility that the abnormal beaks are the result of DNA damage following exposure to a contaminant, or are caused by a deficiency in calcium or vitamin D. However, no clear correlations have yet been found.
Hoping to study a larger sample of the deformed birds, Handel has launched Project Feeder Watch, which asks citizens to report any birds they see with crossed bills or deformed beaks.
