Oregon is trying to say they were poisoned and maybe the eagle ate some of the poisoned small birds. Don't think so
A bald eagle, a red-tailed hawk and dozens of birds drop dead from the sky in Hillsboro, Oregon
Wildlife officials are investigating a mysterious mass bird death in Hillsboro, Oregon, where dozens of red-winged blackbirds and European starlings were found dead in a field off West Union Road, along with a bald eagle and a red-tailed hawk. There were no obvious signs of death. The birds are being tested by wildlife officials to figure out how they died.
https://www.kgw.com/article/news/mysterious-mass-bird-deaths-in-hillsboro/283-615308272