Biologists are concerned about an uptick in bird flu this fall, as migrating birds bring the flu with them as they head south for winter. The current highly pathogenic avian influenza outbreak has been far more widespread among wild birds than past outbreaks, infecting over 100 species across nearly all of the United States. While a previous outbreak in 2015 faded away in the summer, this time, the virus has remained active. It is “radically different than what we’ve seen before,” Bryan Richards, the emerging disease coordinator at the National Wildlife Health Center told the New York Times. As birds head south, cases are climbing in some northern states and appearing for the first time in states like Mississippi, Arkansas and New Mexico.