DistributionRead full entry
Icterus pustulatus, also known as streak-backed orioles, have a range that extends along most of the Pacific coast of Central America. They occur from northwestern Mexico in northeastern Sonora and western Chihuahua south into into Sinaloa, along the coast. Streak-backed orioles are common throughout the rest of the western slope of Mexico. They are seldom observed in Guatemala, but documentation of their range resumes in El Salvador and into central Honduras and western Nicaragua. They have very rarely been seen in the southwestern United States.
In their book, "New World Blackbirds: The Icterids," Alvaro Jaramillo and Peter Burke assert that there are six subspecies of I. pustulatus, divided among three groups.
The northernmost group is the scarlet-headed oriole group. This includes I. p. pustulatus, which occurs south from Colima to Northern Oaxaca and east from Guanajuarto to Merelos, Puebla, and West Vercuz, and I. p. microstictus, which can be seen from Sonora and Chihuahua, south to Jalisco. The northern subspecies are partially migratory. While little is known of their seasonal movements (Jaramillo and Burke 1999), some I. p. microstictus have been observed wintering to the south, in the state of Guerrero (Howell and Webb 1995).
The Tres Marías oriole group consists only of I.p. graysonii. This subspecies is restricted to the Tres Marías islands which lie along the coast of Nayarit, Mexico.
Finally, the largest group, and found farthest to the south, is the streak-backed oriole group. Members of this group include I. p. alticola, found mostly in dry areas of southern Guatemala and central Honduras. Icterus pustulatus sclateri is the most southerly population and may occasionally breed with I. p. alticola, as morphologically intermediate specimens have been found. Icterus pustulatus formosus is found in the extreme south of Mexico and northwestern Guatemala. This subspecies is endemic to the vicinity of Volcán San Miguel, in southern El Salvador. Lastly, I. p. maximus is endemic to the arid Rio Negro Valley in Guatemala (Jaramillo and Burke 2000). In spite of their morphological similarity, all of these subspecies are very closely related and have diverged very recently based on mitiochondrial DNA data (Nandadevi Cortes-Rodriguez, Adolfo Navarro, UNAM Mexico; Kevin Omland, UMBC - unpublished data).
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Other Geographic Terms: island endemic