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.
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.
— Text by Dave Mehlman, Cool Green Science Blog