Bicolored Antvireo Dysithamnus occidentalis Scientific name definitions

The Bicolored Antvireo is a poorly known species of antbird in the genus Dysithamnus that has a disjunct range in western Colombia, eastern Ecuador, and northern Peru. At least three different subspecies involved. It is mainly found in the subtropical zone at middle elevations in the Andes, and appears to be associated with Chusquea bamboo. Males are mostly uniform dark grayish-black, with faint white tips to the wing coverts forming rows of dots on the wings. Females are slaty gray below, brown above, with a brighter chestnut crown. Most likely overlaps (in eastern Ecuador) with very similar White-streaked Antvireo (Dysithamnus leucostictus), but is generally found at higher elevations. Females are quite different, and have bold white streaking on the face and underparts. In Ecuador it has two main vocalizations, a rapid “ji-ji-jerrr,” and a mellow “tew.” In Northern Peru, this species has a more “typical” antvireo song, a descending series of mellow whistles “wee-wee-wee-wu-wuwuwu” speeding up at the end, but this vocalization has not been detected for certain in Ecuador. Song of White-streaked Antvireo much slower. Formerly placed in the genus Thamnomanes and called “Western Antshrike.”

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Loudsong uncertain, may consist of one of the following calls. Calls include a brief series of notes (usually 3, sometimes 2 or 4) falling in pitch and intensity, repeated at rate of 1 per minute (but variable); short (e.g. 0·25 seconds), variable, downslurred whistle; and a short (less than 1 second) rising series of 3 abrupt notes followed by longer note.

VULNERABLE. Restricted-range species: present in Chocó EBA and Ecuador-Peru East Andes EBA. Both subspecies only recently rediscovered following decades without being recorded. Species is still known from only a few areas, one of which (the type locality for punctitectus) has suffered significant clearance for small-scale agriculture (primarily, planting of naranjilla). The recent Colombian record from headwaters of R Pance is from a site that appears to be just outside Farallones de Cali National Park, and it seems likely that this ornithologically underexplored park may contain a population of this species. Locality data from at least two of the Cauca specimens suggest that the sites may lie within current boundaries of Munchique National Park; this is adjacent to the 3000-ha Tambito Nature Reserve, where recent surveys found nominate race to be uncommon. In Ecuador, Volcán Sumaco is still largely pristine, with an intact forest corridor from lowlands to the highlands; large parts of this ecologically important area are protected, at least on paper, within the Sumaco-Galeras National Park. True conservation of this area would provide a significant reserve for punctitectus and many other threatened taxa. Recent range extensions in Ecuador, to Carchi and Morona-Santiago, offer hope that the species may be found in additional locations.