Socorro Mockingbird

The Socorro mockingbird (Mimus graysoni), a stout and distinctive bird, bears a striking resemblance to some thrashers in its general appearance. It is an endangered species, unique to Socorro Island in the Revillagigedo Islands of Mexico. The bird is named in honor of the American ornithologist Andrew Jackson Grayson.

Identification Tips

Adult Socorro mockingbirds exhibit a robust build and possess a distinct juvenile plumage that is more rufous above with a heavily patterned underside. This plumage bears an uncanny resemblance to the gray thrasher of Baja California, although this is a result of convergent evolution rather than relatedness.

Habitat

The preferred habitat of the Socorro mockingbird is the unmodified low forest above 600 meters, where it favors groves of Oreopanax xalapensis and the endemic Guettarda insularis, with an understory dominated by Triumfetta socorrensis and the endemic Eupatorium pacificum.

Distribution

This mockingbird is endemic to Socorro Island, part of Mexico's Revillagigedo Islands, and is not found anywhere else in the world.

Behaviour

Socorro mockingbirds are generally reluctant to fly, preferring to hop away when threatened. They are solitary and aggressive, living alone or with a mate. Social hierarchy is evident when feeding at abundant food sources, with dominant birds feeding first.

Song & Calls

The call of the Socorro mockingbird consists of two medium whistles followed by a lower one. Occasionally, it may produce a full song, a variable warbling tune repeated several times, typical of many mockingbirds. It is not confirmed if this species imitates other birds.

Breeding

The breeding season is extended, with nests attended from November to July and peak laying in March and April. The species lays three eggs, which hatch in no more than 15 days.

Diet and Feeding

The diet includes small invertebrates, remains of land crabs, and fruit from endemic shrubs like Ilex socorrensis and Sideroxylon socorrense. Flies are also consumed but not typically caught in flight.

Conservation Status

The Socorro mockingbird is critically endangered, with fewer than 400 individuals remaining. Threats include habitat loss due to feral sheep and locusts, and predation by feral cats. Conservation efforts are focused on habitat restoration and predator control.