Dabbling ducks suspected in spread of deadly bird flu.

A panzootic outbreak of avian flu has killed hundreds of thousands, if not millions, of wild birds across five continents, including endangered species like the California condor. The virus, which has also infected mammals, including foxes, coyotes, mink, and seals, could pose a threat to humans if it evolves traits that make it more dangerous. The outbreak has become one of the worst wildlife disease outbreaks in history, exacerbating an ongoing extinction crisis and causing an animal welfare crisis in the poultry industry.