The family Hydrobatidae, known as storm petrels, are the smallest of all the seabirds, ranging in size from 13–26 cm in length. Storm-Petrels include the families Hydrobatidae and the Oceanitidae. The Hydrobatinae have longer wings, forked or wedge-shaped tails and shorter legs. The legs of all storm petrels are proportionally longer than those of other Procellariiformes, but they are very weak and unable to support the bird’s weight for more than a few steps.
Storm petrels are notoriously difficult to identify at sea. Storm petrels use a variety of techniques to aid flight. Most species will occasionally feed by surface pattering, holding and moving their feet on the water’s surface while holding steady above the water. This method of feeding flight is most commonly used by Oceanitinae storm-petrels. There is 1 genus and 7 species in the family Hydrobatidae known to occur in Peru. Photo: Elliot’s Storm-Petrel