Monteiro's Storm-petrel, Oceanodroma monteiroi, is a species of seabird in the storm-petrel family, Hydrobatidae. The cryptic species was once considered to be conspecific with the Madeiran Storm-petrel. The species is apparently endemic to the Azores.
The existence of a separate species was first hinted by the discovery of two distinct breeding seasons of Oceanodroma storm-petrels in the Azores. Both these populations were initially thought to be of Madeiran Storm-petrels; however, one population bred in the cool season, and the other in the hot season. Closer study of these two breeding populations found differences in their morphology and moult. Examination of the mtDNA found that the two populations were indeed genetically isolated from each other, and the hot-season-breeding population was elevated to a full species, Oceanodroma monteiroi, Monteiro's Storm-petrel. The species is named for the biologist Dr. Luis Monteiro, who discovered this cryptic species.
Monteiro's Storm-petrel breeds on two islets in the Azores. As in all Procellariiformes, a single egg is laid and is incubated by both parents. The egg-laying period for this species is May to early July (in contrast to the Madeiran Storm-petrel, which on these islands lays in October-December). The first chicks hatch in June and the last chicks fledge by October. The species is thought to forage in the local seas all year round, possibly near the breeding sites; this is in contrast to the Madeiran Storm-petrel, which disperses to the West Atlantic. Their diet is unknown, but analysis of stable isotopes in the feathers suggest that diet is different from that of the Madeiran Storm-petrel as well.
The species has a low reproductive output due to competition with other burrowing petrels, and the young are preyed upon by the Long-eared Owl. Conservation status of the species has not yet been evaluated by the IUCN, but the population is small (estimated at just 250"?300 pairs in 1999) and is in need of protection and active conservation.