The Mascarene Petrel is an all-dark seabird. It breeds on Réunion and ranges widely across the Indian Ocean at different times of year.
Males and females show no obvious color difference. Adults are entirely black, with a short, sturdy bill; part of each leg is pink, while the toes and outer webs are black.
Natural breeding sites are on ledges along difficult-to-reach cliffs on Réunion. Outside the breeding period, records show birds moving to several Indian Ocean areas, including southern Sri Lanka, the Arabian Sea, and the Bay of Bengal.
An extinction-risk assessment has not been added yet.