The Band-rumped Storm-Petrel, which is known as Madeiran Storm-Petrel in Europe, is found both in the Pacific and Atlantic oceans. What seemed like a simple taxonomic situation is becoming quite complex as genetic and vocal studies are published on this complex. The first level of complexity was that on the Azores this storm-petrel had both winter and summer breeding populations, and these differed morphologically, and molecularly; note however that in the Galapagos winter and summer breeders do not show the same level of difference. Traditionally considered a monotypic species, it may indeed result that this storm-petrel is comprised of several species in the Atlantic Ocean alone! More work is needed to sort out exactly how many taxa are involved, and if they all deserve to be at the species level. In South America Band-rumped Storm-Petrels may occur offshore off the northern Atlantic coast of the continent, and these are of unknown form. On the Pacific the species breeds on the Galapagos Islands, with summer and winter breeding population’s there. The unofficial moniker “Darwin’s” Storm-Petrel has been used informally for these birds.