Madeiran Storm-petrel/Oceanodroma castro

The Band-rumped Storm Petrel is 19–21 cm in length with a 43–46 cm wingspan, and weighs 44–49 g. It is mainly black with an extensive white rump. Similar to Leach's Storm Petrel with the forked tail, long wings, and flight behaviour, but Leach's has a more forked tail and differently shaped white rump.

It breeds on islands in the warmer parts of the Atlantic and Pacific Oceans. These include the Azores and Madeira in the Atlantic, and the Galapagos Islands in the Pacific. It nests in colonies close to the sea in rock crevices and lays a single white egg. It spends the rest of the year at sea. They feed by picking up prey items (invertebrates, small vertebrates and sometimes carrion) from the water's surface. Occasionally, they make shallow dives, generally to 40–120 cm below the water's surface; a recorded maximum depth of 170 cm seems highly unlikely and is probably due to equipment malfunction.

This storm petrel is strictly nocturnal at the breeding sites to avoid predation by gulls and skuas, and will even avoid coming to land on clear moonlit nights. Like most petrels, its walking ability is limited to a short shuffle to the burrow.

Recent discoveries of 'cold season' and 'warm season' populations, which use the same nest sites at different times of year, and also differ in terms of vocalisations and moult, may hint at the existence of two 'cryptic species' within the currently understood limits of the species. After population genetic analyzes of mtDNA the warm season population in the Azores have been recognized as a separate species, Monteiro's Storm Petrel.


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