How to Identify Great Shearwater Feathers

What Great Shearwater's Feathers Look Like

The Great Shearwater is a long-distance oceanic wanderer that breeds in the South Atlantic and ranges across the entire Atlantic basin, and its feathers are built for endless dynamic soaring low over waves. Crown and hindneck feathers are blackish-brown, sharply capped, contrasting with a pale, often whitish collar around the neck — a feather pulled from the crown will look distinctly darker and more solidly colored than one from the neck just below it. Back and upperwing covert feathers are grayish-brown with pale buffy fringes, creating a scaly, scalloped "M" pattern across the upperwing when the bird is seen in flight, so an individual back feather often shows a neat pale crescent edge rather than being uniformly dark.

Underparts are mostly white, but many individuals show an irregular dark smudgy patch on the belly, so a white body feather with a blotch of grayish-brown near its tip is still consistent with this species. Uppertail covert feathers are white, forming a pale horseshoe band at the base of the tail that's a useful diagnostic on its own. Flight feathers are long, narrow, and blackish-brown, stiff and tapered for gliding rather than flapping, and the underwing shows white with dark margins and a diagonal dark bar crossing the coverts.

Step-by-Step: Is This Feather From a Great Shearwater?

• Measure it. Primaries typically run 22–27 cm, long and narrow — a shape built for gliding, not the broader flight feathers of a hawk or gull of similar length.
• Check for a dark cap. A blackish-brown feather with a fairly sharp lower edge, as if capping off against paler feathers, fits the crown/nape area.
• Look for scaly fringing. Back and covert feathers with a neat pale buff edge around an otherwise gray-brown feather create the scalloped "M" pattern typical of this species.
• Inspect white feathers for smudging. A mostly white body feather with an irregular dusky patch near the tip is consistent with this species' variable belly patch.
• Note the horseshoe band. White uppertail covert feathers, if found in a cluster, support the pale rump band this species shows at the tail base.
• Consider the source. A feather found washed up on an ocean beach, especially after a storm, fits this pelagic species far better than a shorebird or gull that frequents the same coastline.

Similar Species & How to Tell Them Apart

The Cory's Shearwater, sharing much of the same North Atlantic range, is larger and paler overall with a more uniform grayish-brown head that lacks the Great Shearwater's sharply demarcated dark cap, and it typically lacks the bold scaly upperwing pattern. The Sooty Shearwater is entirely dark sooty-brown both above and below, with a silvery-white underwing lining, quite different from the Great Shearwater's white belly and dark cap. The much smaller Manx Shearwater shows crisp black-and-white contrast with no scaly back pattern and noticeably smaller feathers overall.

Where & When You'll Find Them

Great Shearwaters breed on a handful of remote South Atlantic islands, chiefly the Tristan da Cunha group and Gough Island, during the austral summer, then undertake a massive transequatorial migration to spend the Northern Hemisphere summer and autumn feeding across the North Atlantic, including waters off eastern North America and Europe. Because they molt flight feathers gradually while in these northern waters before returning south, worn or dropped feathers most often wash ashore on North Atlantic coastlines from late spring through autumn, especially after strong onshore storms that strand feathers and, occasionally, exhausted birds.