Procellariiformes
Diet and feeding

The procellariiforms are for the most part exclusively marine foragers; the only exception to this rule are the two species of giant petrel, which regularly feed on carrion or other seabirds while on land. While some other species of fulmarine and Procellaria petrels also take carrion, the diet of most species of albatrosses and petrels is dominated by fish, squid, krill and other marine zooplankton. The importance of these food sources varies from species to species and family to family. For example, of the two albatross species found in Hawaii, the black-footed albatross takes mostly fish, while the Laysan feeds mainly on squid. The albatrosses in general feed on fish, squid and krill. Among the procellariids, the prions concentrate on small crustacea, the fulmarine petrels take fish and krill but little squid, while the Procellaria petrels consume mainly squid. The storm petrels take small droplets of oil from the surface of the water, as well as small crustaceans and fish.

Petrels obtain food by snatching prey while swimming on the surface, snatching prey from the wing or diving down under the water to pursue prey. Dipping down from flight is most commonly used by the gadfly petrels and the storm petrels. There have been records of wedge-tailed shearwaters snatching flying fish from the air, but as a rule this technique is rare. Some diving birds may aid diving by beginning with a plunge from the air, but for the most part petrels are active divers and use their wings to move around under the water. The depths achieved by various species were determined in the 1990s and came as a surprise to scientists; short-tailed shearwaters have been recorded diving to 70 m (230 ft) and the Light-mantled sooty albatross to 12 m (39 ft).
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