What’s this about dead Great Shearwaters on our beach?

On June 27, residents of Seabrook Island began hearing about sick and dead Great Shearwaters being seen from Murrells Inlet to Miami, Florida. A first reaction was “What’s going on here?” Research showed that although the strandings are not a good thing, the knowledgeable people are not concerned as this occurs every couple years.

Great Shearwaters are a common seabird off our Atlantic Coast, seldom coming close to shore except during storms. They often forage in flocks, commonly feeding around fishing boats, fighting over scraps and offal, seemingly fearless of humans. It is a medium-sized seabird (L: 19 inches) that is smaller than most gulls. Long, narrow wings are held quite straight when flying as it flies on deep wing beats followed by long glide. It has scaled, gray-brown upper parts, white underparts, and brown markings on belly. A dark cap contrasts with its white face. Its tail is dark above with conspicuous white rump band and gray below. The bill is dark and hooked. Its legs and feet are pink.  Pictures from Audubon’s web site are shown below.

Great Shearwater – Photo Credit Audubon
Great Shearwater – Photo Credit Audubon

Shearwaters are among the most widespread, abundant seabirds on the world’s oceans but are rarely seen on beaches. Although Great Shearwaters are often very numerous in North American waters, they nest only on a few islands in the South Atlantic almost half way between Africa and South America. In April they leave their breeding grounds and move north rapidly, mostly along western side of Atlantic, becoming common off the East coast of North America in June. They then spread eastward across North Atlantic during summer, and a southward migration is on a broad front during August. Non breeders remain in the North Atlantic at least through November.

Seabirds, especially Great Shearwaters, are greatly affected by oceanic conditions such as fronts, currents, salinity and surface temperature that affect the distribution and abundance of plankton and phytoplankton. Juveniles are especially susceptible to these variations. Al Segars of the South Carolina Department of Natural Resources indicates the stranding of Great Shearwaters on our beaches happens every couple of years at about this time. The birds appear to fall out during migration due to malnutrition and starvation. This occurs primarily during periods of onshore winds. Similarly, a 2009 article to the Carolina Bird Club says “Actually, spring migration die-offs of this species occur regularly and probably nearly annually. The magnitude of the die-offs, the degree of documentation, and the amount of media coverage are of course highly variable.”

Currently, the Center for Birds of Prey are interested in treating the sick Great Shearwaters and doing necropsy on the dead. Contact Glen Cox (703-201-8934) if you encounter a stranded Great Shearwater. The pictures below were provided by Glen. The first is of a Great Shearwater that died while being transported to the Center for Birds of Prey from Botany Bay and the second was seen at the inlet.

Great Shearwater – transported to the Center for Birds of Prey – Glen Cox
Great Shearwater found at the inlet on North Beach – photo by Glen Cox

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– Submitted by Judy Morr, Seabrook Island Birders Executive Board Member

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