In the 1990s, eagles in the Southeastern U.S. began dying of a mysterious brain disease. Many years of research identified the culprit: a cyanobacteria that grows on an invasive aquatic plant called Hydrilla — also known as waterthyme. Fish ingested the cyanobacteria, and eagles ate the affected fish. Biologists are now working to contain Hydrilla to prevent more harm to ecosystems. Learn more about invasive plants and their effect on birds, waterways and more on this special season of the Bring Birds Back podcast.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.