Expanding the marine range of the endangered black-capped petrel Pterodroma hasitata: Occurrence in the northern Gulf of Mexico and conservation implications

ABSTRACT

The black-capped petrel (Pterodroma hasitata) is an endangered seabird endemic to the western north Atlantic. Although estimated at ~ 1,000 breeding pairs, only ~ 100 nests have been located at two sites in Haiti and three sites in the Dominican Republic. At sea, the species primarily occupies waters of the western Gulf Stream in the Atlantic and the Caribbean Sea. Due to limited data, there is currently not a consensus on the marine range of the species. There are several maps in use for the marine range of the species and these differ with respect to the north, south, and eastward extent of the range. None of these maps, however, includes the Gulf of Mexico. Here, we report on observations of black-capped petrels during two vessel-based survey efforts throughout the northern Gulf of Mexico from July 2010 - July 2011, and from April 2017 - September 2019. During the 558 days and 54.7 km of surveys from both efforts we tallied 40 black-capped petrels. Most observations occurred in the eastern Gulf, although birds were observed over much of the east-west and north-south footprint of the survey area. Predictive models indicated that habitat suitability for black-capped petrels was highest in areas associated with dynamic waters of the Loop Current, similar to habitat used along the western edge of the Gulf Stream in the western north Atlantic. We suggest that the range for black-capped petrels be modified to include the entire northern Gulf of Mexico although distribution may be more clumped in the eastern Gulf and patchier elsewhere. It remains unclear, however, which nesting areas are linked to the Gulf of Mexico.