The bird field guides call the shearwaters and petrels “regular visitors”. They certainly are… they are regular visitors from far off coastlines and waters almost half way around the world.Individuals belonging to these species are seen in the waters off North America and South Africa. The same birds are not seen in these areas, but the species themselves are truly global in distribution.
My frequent travels between Norfolk, Virginia USA and points west for my work take me across the Hampton Roads Bridge Tunnel. In the middle of the tunnel’s crossing of a narrow portion of the Chesapeake Bay is a small artificial island where the maintenance crews keep their equipment so they can help those whose automobiles have stalled out in the tunnel. About half the island is set aside as a breeding area for seabirds. Sharing this island with gulls, endangered Least Terns and Common Terns are
Greater Shearwaters, here to spend some time relaxing. In the summer they will head back north.But in the cooler months along the United States’ east coast estuaries and large bays, they rest and put on weight for the hard work of breeding and nesting in the springin more northern latitudes. When they settle down to lay, they lay just one egg in a nest of feathers hidden in a rock crevice. That is their production of eggs for the year. One might think that such a slow rate of reproduction might make them rare birds. Many birds that reproduce in this way are indeed rare, but the shearwaters are among the more abundant and well distributed birds of the world. Most people are not familiar with shearwaters unless they spend time at sea oron the islands where they breed or rest. The Greater Shearwaters are roughly the size of gulls, about 45 centimeters in length, and can be distinguished from gulls by their darker colors and their stiff wingbeats. This species, called the “muttonbird” by New Zealand’s Maoris who use it for meat and oil, is also known by its scientific name Ardenna gravis, and occurs in the South Atlantic and south-western Indian Oceans, over southern sub-tropical and subantarctic waters. Many of the birds migrate to the North Atlantic during the southern winter. The Greater Shearwater’s range off the coast of Africa takes an interesting shape. They avoid the western coast of Angola and upward to Nigeria, and frequent only the coast of Namibia and the western and southern coasts of South Africa, and the northwest coast of the continent.
In the cloudy, chilly months of November in Virginia, after the thousands of tourists have long ago left the beaches and attractions, I see these birds near the tunnel and bridge, swooping low over the water’s surface, as though shearing off a bit of water. I have occasionally seen them plunge into the water to snatch marine life for a meal. Their life stories are similar to those of the smaller Manx Shearwater (Puffinuspuffinus), the Sooty Shearwater (Ardennagrisea) and the Wilson’s Storm Petrel (Oceanitesoceanicus),
all birds one can see following ships for scraps or breeding on islands near the Cape of Good Hope. The Manx Shearwater is about 33 centimetres in length and the little Wilson’s storm petrel is a mere 12.7 centimetres in length. Members of the tubenose family, their nostrils are two tubes situated atop their upper bill. With the help of the tubes the birds excrete salt accidentally ingested when they feed on fish, cephalopods and crustaceans. The shearwaters and petrels are not as long lived as parrots but they do live far longer than most birds. One individual Manx Shearwater was banded by a scientist in 1953 when the bird was already an estimated five years of age. In July 2003 it was trapped and the band examined. The bird was the same one originally trapped in 1953.
It is early autumn in North America now so I can look forward to glimpses of the Greater Shearwater, the Sooty Shearwater and perhaps even the Wilson’s Storm Petrel. But South Africans can see them all year long, skimming the constantly changing surface of the waves or walking briefly on the water to get airborne.