Cory’s Shearwater: Seashore Saturday

The last few weeks have been about shorebirds, so today I wanted to write about a seabird.

Cory’s Shearwater (Calonectris diomedea)


Cory’s Shearwaters are the largest of the North American Shearwaters at around 19″.  They have sandy brown upperparts and white underparts. Their heads are mainly dark and their wings are broad and arched. Cory’s have distinctive, heavy yellow bills.

Cory’s Shearwater (Image by Adin Vella via


Found along the Atlantic and Gulf Coasts between March and October. . Cory’s have an extremely large range. They are native to North America, Africa, Europe, and many island nations. Savage Islands, Madeira, has the largest breeding colony of Cory’s Shearwaters.


Open oceans. Cory’s prefer warm waters. They nest on mountainous or rocky islands.


Fish, crustaceans, and squid. Cory’s forage by plunge diving into the water and grabbing prey from below the surface. Like many other seabirds, Cory’s also scavenge for food near fishing boats and sometimes associate with whales who scare small schools of fish to the surface. Cory’s are usually solitary but will gather in flocks with other shearwaters where food is abundant.

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Cory’s Shearwater in flight (Image by Jeff Slovin via


Cory’s Shearwaters breed between March and October in large colonies that are mainly active later in the day. During courtship pairs will sit close together and preen each others’ heads and bills. They mainly nest in crevices, burrows, or on the ground using shells and small pebbles. Females lay one egg per year that is incubated by both parents for 52-56 days. They parents feed the young primarily at night and eventually the chick goes out to sea to feed on their own. When tending to the young, parents switch incubation roles around every 6 days.  The young fledge about 90 days after hatching.

A Cory’s Shearwater at its nesting site (Image by Coimbra68 via wikimedia commons)


Silent when out at sea.

Fun Facts:

  • This species of  shearwater was named after American ornithologist Charles B. Cory.
  • Cory’s Shearwaters are in the family Procellariiformes, more commonly known as tubenoses. Members of this family have have distinctive nostrils, that are covered by tubes on their upper bills. Since they drink salt water they have to excrete excess salt. The nasal glands are above the eyes at the base of the bill. This gland removes salt and creates as saline solution that drips out of the nostrils of their bills. Tubenose birds have a great sense of smell, which aids them in finding prey as well as their nest sites.


Author: BirdNation

I am an avid birder, teacher, and nature lover. I primarily go birding in New Jersey and Pennsylvania, but love to travel. I am currently a biology student with interests in conservation biology, ornithology, and environmental sciences. My dream is to go birding in all 50 states.

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