GREAT SHEARWATER
GREAT SHEARWATER – (Ardenna gravis) – (See images below)
DESCRIPTION: The Great Shearwater is a pelagic (open sea) seabird with a dark brown head and upper parts, and white under parts with a washed out patch of brown on the belly. There is also another brown patch at the shoulders. Eyes and bill black, legs and feet pinkish. Bill upper mandible ends with a hook. Under side of the wings is white with brown edges. Both sexes are similar. Measures some 50 cm (20 inches) long.
VOICE: https://www.xeno-canto.org/species/Ardenna-gravis
NAME: ‘Shearwater’ stems from the way the bird flies over water, holding their long, narrow wings straight near the tip of the waves, almost ‘shearing’ them. The Latin genus name ‘Ardenna’ refers to a ‘seabird’, and the Latin species name ‘gravis’ means ‘heavy’.
HABITAT: Pelagic (open seas), only come to land (rocky islands) to breed.
DIET: Small fish, squid and crustaceans from schools near the water surface. Dive and swim under water to pursue their prey. Also feed near whales and dolphins, when those mammals bring schools of fish near the surface. Follow fishing vessels for scraps of fish. Feed in huge flocks sometimes, and can fight noisily over pieces of food.
NESTING: Great shearwaters breed in large colonies on isolated rocky islands, digging burrows around one meter (3 ft) long with a chamber at the end, at a higher level. They build their nest in that chamber, lay one white egg, and only visit the nest at night to deter predators. Incubation probably by both parents. Chick fed by both parents.
DISTRIBUTION: Breeds on small islands in the South Atlantic Ocean, such as Gough and Tristan da Cunha. Migrates north during the southern winter, ends up in the North Atlantic Ocean. This bird is one of the rare species with this ‘reverse’ migrating route.
DISTRIBUTION MAP: https://en.wikipedia.org/wiki/Great_shearwater#/media/File:Ardenna_gravis_map.svg
ON PEI: Does not breed on Prince Edward Island, occurrence recorded as ‘uncommon’ for summer and fall, most likely following storms.
CONSERVATION: Although numbering in the millions, adults and eggs of the great shearwater are harvested on their breeding grounds for human consumption at ‘unsustainable levels’. Being a species that builds an underground nest, it is highly vulnerable to feral predators such as rodents. Mice are present on some of their breeding islands and exact a toll. In spite of those threats, the species is currently listed as of ‘least concern’.
NOTES: Shearwaters are part of the Tubenose order of birds. They have a highly specialized bill made of plates, and the nostrils are inside one of them in the shape of a ‘tube’. They can drink seawater, and have glands in their bill to extract the salt from the water. Their nostrils also have a self-defensive feature – when threatened the great shearwater can spit out a foul-smelling oil from that organ.
SIMILAR SPECIES: Buller's shearwater, White-naped petrel
REFERENCES: https://en.wikipedia.org/wiki/Great_shearwater
https://www.audubon.org/field-guide/bird/great-shearwater
https://identify.whatbird.com/obj/616/overview/Great_Shearwater.aspx
http://www.neseabirds.com/birdsshearwatergreat.html (New England Seabirds)
http://nzbirdsonline.org.nz/species/great-shearwater (New Zealand Birds Online)
https://britishwildlife.fandom.com/wiki/Great_Shearwater
http://www.oiseaux-birds.com/card-great-shearwater.html
DESCRIPTION: The Great Shearwater is a pelagic (open sea) seabird with a dark brown head and upper parts, and white under parts with a washed out patch of brown on the belly. There is also another brown patch at the shoulders. Eyes and bill black, legs and feet pinkish. Bill upper mandible ends with a hook. Under side of the wings is white with brown edges. Both sexes are similar. Measures some 50 cm (20 inches) long.
VOICE: https://www.xeno-canto.org/species/Ardenna-gravis
NAME: ‘Shearwater’ stems from the way the bird flies over water, holding their long, narrow wings straight near the tip of the waves, almost ‘shearing’ them. The Latin genus name ‘Ardenna’ refers to a ‘seabird’, and the Latin species name ‘gravis’ means ‘heavy’.
HABITAT: Pelagic (open seas), only come to land (rocky islands) to breed.
DIET: Small fish, squid and crustaceans from schools near the water surface. Dive and swim under water to pursue their prey. Also feed near whales and dolphins, when those mammals bring schools of fish near the surface. Follow fishing vessels for scraps of fish. Feed in huge flocks sometimes, and can fight noisily over pieces of food.
NESTING: Great shearwaters breed in large colonies on isolated rocky islands, digging burrows around one meter (3 ft) long with a chamber at the end, at a higher level. They build their nest in that chamber, lay one white egg, and only visit the nest at night to deter predators. Incubation probably by both parents. Chick fed by both parents.
DISTRIBUTION: Breeds on small islands in the South Atlantic Ocean, such as Gough and Tristan da Cunha. Migrates north during the southern winter, ends up in the North Atlantic Ocean. This bird is one of the rare species with this ‘reverse’ migrating route.
DISTRIBUTION MAP: https://en.wikipedia.org/wiki/Great_shearwater#/media/File:Ardenna_gravis_map.svg
ON PEI: Does not breed on Prince Edward Island, occurrence recorded as ‘uncommon’ for summer and fall, most likely following storms.
CONSERVATION: Although numbering in the millions, adults and eggs of the great shearwater are harvested on their breeding grounds for human consumption at ‘unsustainable levels’. Being a species that builds an underground nest, it is highly vulnerable to feral predators such as rodents. Mice are present on some of their breeding islands and exact a toll. In spite of those threats, the species is currently listed as of ‘least concern’.
NOTES: Shearwaters are part of the Tubenose order of birds. They have a highly specialized bill made of plates, and the nostrils are inside one of them in the shape of a ‘tube’. They can drink seawater, and have glands in their bill to extract the salt from the water. Their nostrils also have a self-defensive feature – when threatened the great shearwater can spit out a foul-smelling oil from that organ.
SIMILAR SPECIES: Buller's shearwater, White-naped petrel
REFERENCES: https://en.wikipedia.org/wiki/Great_shearwater
https://www.audubon.org/field-guide/bird/great-shearwater
https://identify.whatbird.com/obj/616/overview/Great_Shearwater.aspx
http://www.neseabirds.com/birdsshearwatergreat.html (New England Seabirds)
http://nzbirdsonline.org.nz/species/great-shearwater (New Zealand Birds Online)
https://britishwildlife.fandom.com/wiki/Great_Shearwater
http://www.oiseaux-birds.com/card-great-shearwater.html
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| Great shearwater off NC, Patrick Coin |
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| Great shearwater in flight, J.J. Harrison |
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| Great shearwater off NC, Patrick Coin |
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| Great shearwater top view, NC, Dick Daniels |
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| Great shearwaters fighting, NC, Dick Daniels |