Once, California’s Suisun Marsh hosted the state’s largest breeding population of northern harriers. However, their populations have steadily declined over the past few decades, in part due to a loss of habitat.

Now, USGS biologists are studying northern harrier movements, habitats, and nesting behavior to inform ongoing wetland conservation efforts. The research is helping programs that aim to understand the ecology of Suisun Marsh and prevent population declines.

Pictured: An adult male Northern Harrier (Circus cyaneus) surveys Suisun Marsh, CA. Males are known for their beautiful, steel-gray plumage. Credit Billy Thein/USGS.