A group of American Crows (possibly up to 4) were calling, one was making a “rattle” (a similar sound to the “knocking” sound of Common Ravens). In this partial recording, 12 “rattles” can be heard in under 2 minutes.
Recording location is Cobscook Point at Cobscook Bay State Park in Edmunds Township, Maine. at 10:09 am on August 10, 2021.
The full recording, 8.5+ min, can be heard here: macaulaylibrary.org/asset/361178511