A Band-rumped Storm-Petrel (Oceanodroma castro) banded in the Azores was recovered in the Gulf of Mexico south of Pensacola, Florida. Research in breeding colonies in the Azores indicates that two genetically distinct breeding forms of this storm-petrel exist, one that breeds in the cool season (August–January), another that breeds in the hot season (April–September). The individual recovered from the Gulf was a representative of the cool-season breeders. Only recently has it become known that Band-rumped Storm-Petrels are regular in the western Atlantic Ocean when not breeding. Based on recent reports (sightings) and records (salvaged specimens), probably they also are regular in the Gulf of Mexico. If the two forms are determined to be separate species, a new challenge exists, namely to determine if they are distinguishable other than from measurements and genetic analysis. Careful record keeping and willingness to donate specimens to research institutions by persons in charge of rehabilitation facilities could help clarify this situation and others related to the distribution of pelagic birds.