Pterodroma inexpectata

Mottled Petrel

Family: Procellariidae · Class: Aves · Order: Procellariiformes

The Mottled Petrel is a medium-sized seabird with distinctive plumage patterns that distinguish it from other petrels in the North Pacific. Adults measure 33 to 35 cm (13 to 14 inches) in length with a wingspan of 74 to 82 cm (29 to 32 inches). The species exhibits a dark gray-brown dorsal surface with a distinctive white belly and underwing pattern. The wings display a characteristic dark 'M' pattern across the back when viewed from above, formed by darker flight feathers contrasting with lighter wing coverts. The underwings show a distinctive dark diagonal stripe from the body to the wingtip, creating a bold pattern against white underwing coverts. Mottled Petrels breed exclusively on islands off New Zealand, including the Snares Islands, Stewart Island, and several offshore islets. During the non-breeding season, the species undertakes extensive trans-Pacific migrations, with regular occurrence in waters off California from May through October. The species is most commonly observed in deep oceanic waters beyond the continental shelf, typically 50 to 200 kilometers offshore of California. Mottled Petrels occasionally venture closer to shore during periods of strong onshore winds or when following upwelling events that concentrate prey. The species inhabits pelagic marine environments, preferring areas where cold, nutrient-rich waters support abundant planktonic life. Off California, Mottled Petrels are most frequently encountered in areas of upwelling along the continental shelf edge, where water depths exceed 1,000 meters. The species shows preference for areas with sea surface temperatures between 12 and 18°C (54 to 64°F), often associating with other seabirds at convergence zones where different water masses meet. Mottled Petrels are primarily nocturnal feeders, using their excellent night vision to locate prey at the sea surface. The diet consists mainly of small fish, squid, and crustaceans, particularly lanternfish and other mesopelagic species that migrate vertically in the water column. The species employs surface-seizing and shallow diving techniques to capture prey, rarely diving deeper than one meter. Breeding occurs during the austral summer from November to April on New Zealand islands, where pairs excavate burrows in soil or nest among rocks and vegetation. The Mottled Petrel is not federally listed in the United States, as it is not a breeding resident. The species is considered Near Threatened globally by the IUCN, with an estimated population of 150,000 to 200,000 individuals. Primary threats to the breeding population include introduced predators on nesting islands, habitat degradation, and climate change effects on marine food webs. In California waters, the species faces potential threats from plastic pollution, oil spills, and fisheries bycatch, though quantitative impacts on the population are not well documented. Conservation efforts focus primarily on predator control and habitat protection at breeding sites in New Zealand.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.