Uncommon and often local winter migrant to coastal bays and inshore waters. Less often, singles occur on reservoirs and larger lakes; breeds at lakes in remote northern moorland. Smaller and sleeker than Common Loon (Great Northern Diver). Larger and darker than Red-throated Loon, with straight, daggerlike bill. All plumages have white "hip patch" usually visible on swimming birds. Breeding plumage distinctive, with pale gray head and hindneck, white-checkered back. Nonbreeding plumage has an even border between gray and white on neck (jagged on Common), and gray hindneck paler than back.