The Masatierra Petrel is part of the Cook’s Petrel assemblage, often referred to as the subgenus Cookilaria, and occupies the southeastern portion of Cookilaria’s Pacific Ocean distribution. This species is moderately differentiated from the Cook’s Petrel with a stouter bill and darker eye patch. Still, the most distinctive attribute of this species relative to the other members of its subgenus is its breeding range, which is confined to three islands off the coast of Chile: Juan Fernandez Island, San Ambrosio Island and San Felix Island. Very little is known about this species, but presumably it is highly pelagic and it likely feeds on marine invertebrates such as squid. It is considered Vulnerable due to its extremely small (estimated at a few hundred), though stable, population.