According to a new study, an evolutionary shift around 2020 helped the bird flu virus adapt better to wild birds.

Out on his farm in Dundee Township, Cliff McConville sees geese landing in the fields where his turkeys and chickens graze. It's a sight that often unnerves poultry producers, as migratory waterfowl carry and spread a highly infectious strain of bird flu that has been resurging in the United States for the last three years.