According to a U.S. Geological Survey study on beak deformities, northwestern crows in Alaska, Washington and British Columbia follow a trend found earlier in Alaska's black-capped chickadees. Beak deformities are more than 10 times higher compared to the regular bird population and are called "avian keratin disorder". The cause hasn't been determined yet.
Go to this Oregonian website to read the full article. The study was published in the journal "The Auk" recently.