Original description: Pipilo socorroensis Grayson 1867
Taxonomic history in AOU/AOS Check-list
AOU 6 (1983): Rufous-sided Towhee, Pipilo erythrophthalmus socorroensis
AOU 7 (1998): Spotted Towhee, Pipilo maculatus socorroensis
IUCN Conservation Status: Endangered
In the nineteenth century, visitors to Socorro found this bird “abundant” or “very common” across the island. In the 1990s, it was still said to be common to fairly common, and has recently been reported as common in forested areas at the island’s higher elevations.
Like many other oceanic islands, Socorro has suffered from the introduction of non-native vertebrates including sheep, housecats, lizards, and rodents. Grayson himself had abandoned a pair of domestic hogs on his first visit to the island in 1865, and was “gratified” in 1867 to find the sow “very fat, and far advanced in pregnancy.” By 2010, thanks to eradication efforts, the only invasive introduced mammals remaining on Socorro were the housecat and the house mouse. The immediate impetus for habitat restoration on the island is the scheme to re-introduce the severely endangered Socorro Dove (a species, now extinct in the wild, named in memory of Grayson’s son), but the removal of introduced predators and grazing ruminants is likely to be benefit native ground-feeding birds as well.H
Behavior: Where other Spotted Towhees are shy to the point of furtiveness, almost invariably keeping close to deep, dark cover, Socorro Towhees have been described from the very beginning as notably bold. Grayson found them “as tame as domestic fowls,” easily attracted to crumbs and basins of water; on his visit to Socorro a generation later, Anthony considered them “uniformly confiding, and often half a dozen would congregate within a few feet of a person, silently inspecting him with an air of trustful curiosity quite foreign to other species of the genus.”
Like other large sparrows, Socorro Towhees eat both seeds and insects, scratching and kicking through dried leaves and grass in search of prey.
Voice: The calls of the Socorro Towhee include a thin, hissing tzee and a harsh, rising and falling tzhurrEEa. A clearer, more musical doREE recalls the contact notes of some Eastern Towhees from the southern part of that species’ range.
The Socorro Towhee’s songs, like those of other Pipilo towhees, are variable. The song typically begins with one to three call-like notes, harsh or sweet, and concludes with a louder, higher-pitched buzz or rattle.
Detailed description and measurements drawn from standard reference works
Adult: Tail feathers, upper tail coverts, rump, back, head, throat, and upper breast olive-brown, warmer brown in male. Outer two pairs of tail feathers with small oval white spot at tip of inner web. Scapulars with small white spot at tips. Primaries and secondaries dark brown with faint gray edges. Tertials blackish brown tipped with white. Greater and median coverts blackish brown with white spot at tip, forming two conspicuous white wing bars.
Under tail coverts and vent pale rust. Center of belly and lower breast white, flanks and lower breast sides bright rust. Variable white spot on center of throat.
Length 147-179 mm (5.8-7.0 inches)
Wing chord 64-74 mm (2.5-2.9 inches)
Tail 70-81 mm (2.8-3.2 inches)