Fresh Storm-Petrel Nesting Burrow

Fresh excavation of a storm-petrel nesting burrow on an island in Humboldt County. Note the fresh dirt that has been scraped by the bird onto grass in front of the burrow entrance. Storm-petrels only visit these secretive sites nocturnally and are very difficult to monitor or study, which is why USGS biologists are using acoustic monitoring technology to detect storm-petrel vocalizations at sites spanning the entire coast of California.