Cory's Shearwater is a large Shearwater species of the Atlantic. They breed in the Mediterranean and on islands in the eastern Pacific, but wander widely after the breeding season. In North America, they are most often seen off the East Coast in summer or early fall. It is thought that most birds seen off North America are likely juveniles or non-breeding adults. They tend to prefer areas with relatively warmer waters, and thus in North American waters, are often seen in and around the Gulf Stream.
Habitat
Nests on islands with suitable nesting habitat, either islands with soil suitable for digging burrows, or rocky islands with crevices for nesting. Outside of the breeding season, they disperse widely in the Atlantic, usually over warmer water areas or areas with upwelling currents.
Diet
The Cory's Shearwater feeds primarily on fish, squid, and other marine organisms captured near the ocean surface. It often forages by pattering on the water, making shallow dives, or seizing prey while sitting on the surface, and it frequently follows schools of predatory fish, dolphins, whales, and fishing vessels to take advantage of concentrated food sources.
Behavior
Forages by flying above the water's surface, and plunge diving from near the water's surface. They will also swim on the water's surface and grab items with their bill. They will also follow fishing boats for discarded scraps.
Nesting
Colonial breeder. Nests are usually burrows in the ground, but they will also sometimes use crevices in rocky areas, or nest on the ground in thickly vegetated areas. The nest itself is a basic pile of shells, pebbles, and other debris. The female lays a single egg, and both parents help to incubate it. Upon hatching, both parents help to feed and raise the nestling.
Song
The Cory's Shearwater is generally silent at sea but becomes highly vocal at breeding colonies, especially at night. Its calls are loud, eerie, and far-carrying, often described as wailing, moaning, cackling, or cat-like cries. These haunting vocalizations are used for mate recognition, territorial defense, and communication among birds nesting in burrows and rocky crevices.
Migration
The Cory's Shearwater breeds on islands in the northeastern Atlantic, particularly in the Azores, Madeira, Canary Islands, and other Atlantic archipelagos. After breeding, it undertakes a long transoceanic migration, crossing the Atlantic to winter mainly in the South Atlantic off the coasts of Brazil, Argentina, and southern Africa. During migration, some birds regularly occur off the eastern coast of North America, particularly in the western North Atlantic, where they are a familiar pelagic species.
Similar Species
Most likely to be confused with Great Shearwater in range. The two species are similar in size, with light coloring below and dark coloring above, but Cory's Shearwaters have a much "cleaner" look on the underwing, with white and a dark border. Cory's Shearwaters also have a thick yellow bill, vs. the thin black bill of a Great Shearwater.
Conservation Status
The Cory's Shearwater is generally considered a species of low conservation concern, with a large global population and extensive range across the Atlantic Ocean. However, breeding colonies can be affected by introduced predators such as rats and cats, disturbance at nesting sites, light pollution, bycatch in fisheries, and marine pollution. Continued protection of nesting islands and reduction of threats in marine environments are important for maintaining healthy populations. The IUCN lists the Cory's Shearwater as a species of "Least Concern".
Photo Information
Photo taken by Artie Kopelman - Photo licensed under Creative Commons Attribution NonCommercial 2.0 Generic license .
Interactive eBird Map
Click to access the interactive eBird species sightings page for Cory's Shearwater
