First records of Macgillivray’s prion Pachyptila macgillivrayi in Uruguayan and Argentine waters

The MacGillivray’s prion Pachyptila macgillivrayi is a small petrel that breeds at Saint-Paul Island, Indian Ocean, in addition to a population recently discovered at Gough Island, central-southern South Atlantic Ocean. The non-breeding distribution of the Gough Island population is poorly known. Tracking data revealed a westward dispersion to oceanic waters off southeastern South America. Here, we report photographs of a MacGillivray’s prion taken in waters off Argentina on 5 March 2017 and off Uruguay on 21 July 2022. These constitute the first photo documentation of the species for Uruguay and Argentina, where it appears to be foraging extensively after its breeding season.