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Art by Barry Kent MacKay

(Artwork - 238)
Great Shearwater (Ardenna gravis)

The Great Shearwater (Ardenna gravis) ranges over most of the Atlantic Ocean. Shearwaters belong to the family, Procellariidae, also known as the “tube-nosed swimmers” because their nostrils are at the end of small, tubular projections on the top of the beak. Shearwaters soar, often very low to the ocean’s surface, on stiffly spread wings, at times just touching, or “shearing”, the water with their wingtips. The Great weighs about 720 to 950 grams (about 25.4 to 33.5 ounces) and has a wingspread of about 105 to 122 cm., or about 3.5 to 4 feet, roughly a meter, or somewhat longer than a yardstick.

I saw the species for the first time one foggy day nearly sixty years ago, while crossing the Bay of Fundy from New Brunswick to Nova Scotia, in August. They were easily identified by the dark cap, narrow white rump patch, and a smudge of brownish colour on the belly that looks like a smear of dirt but is an actual marking. They, and the Sooty Shearwaters and the Cory’s Shearwaters keeping them company, were my first tube-nosed swimmers and were thrilling to watch, so adept were they at gliding through the troughs formed between waves that towered over them.

Yes, it was August, but these birds were on their wintering grounds, because where they nest, in the southern hemisphere, it was winter. Their migration route may take them across the Atlantic after first following the coast, often well out to sea, off South and North America, then crossing to Europe and then heading back south to a tiny archipelago of islands known as Tristan da Cunha, the only place where they have been found to nest, which they do during the austral summer. I have shown the distinctive, volcanic shape of Tristan, the main island, off on the horizon. Nearby are the other breeding grounds, Nightengale, Inaccessible and Gough Islands.

Great Shearwaters nest in colonies, having a single egg, often laid in small burrows or declivities in the grass, or on open ground. While predation of eggs or chicks by native gulls and other predatory scavengers is high, the most serious threat to eggs and young are non-native mice which also threaten the critically endangered Tristan Albatross (Diomedea dabbenena), which only nests on Gough Island. There the single chick this large seabird produces may be eaten alive by the mice, which are rapidly evolving into rat-sized predators. I have shown a Tristan Albatross in the background of my painting, although too far away to be distinguished from some similar species. They are nearly identical to the Snowy Albatross (D. exulans) and so were not formally identified as a distinct species until 1998.

Because the shearwaters eat fish and various marine organisms, including offal dumped by fishing boats, they have evolved to grab and swallow objects on or a little below the surface. That has led to them swallowing a lot of plastic waste, which is non-digestible, and can block their stomachs and intestines, leading to a slow death. Great Shearwaters are among the most heavily impacted seabird species, with the highest incidence of plastic in their digestive systems. They, like other seabirds, are also highly vulnerable to oil slicks, drowning in fish nets, and being caught on hooks attached to longlines, some kilometers long, set by commercial fishers.

The painting is in oils on compressed hardboard and is about 20 by 16 inches in size. Oh…and I also attached a detail from a little study in acrylics I did very many years ago, of a Great Shearwater with a Humpback Whale background. I was going to some day use the idea in a full painting, but never got around to it.

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