The sooty-faced finch (Arremon crassirostris) is a species of bird in the family Emberizidae, the New World sparrows. It is found in Colombia, Costa Rica, and Panama.AviList Core Team. 2025. AviList: The Global Avian Checklist, v2025. https://doi.org/10.2173/avilist.v2025 retrieved June 11, 2025
Taxonomy and systematics
The sooty-faced finch has a complicated taxonomic history. It was formally described in 1865 with the binomial Buarremon crassirostris. In 1898 Robert Ridgway erected a new genus for it, Lysurus. He also assigned what is now the olive finch (then Buarremon castaneiceps, now Arremon castaneiceps) to the new genus. In 2008 taxonomists began merging Lysurus into Arremon.Richard C. Banks, R. Terry Chesser, Carla Cicero, Jon L. Dunn, Andrew W. Kratter, Irby J. Lovette, Pamela C. Rasmussen, J. V. Remsen, Jr., James D. Rising, Douglas F. Stotz, and Kevin Winker. "Forty-ninth supplement to the American Ornithological Society s Check-list of North American Birds". The Auk 2008, vol. 125:758-768 retrieved January 27, 2023 The sooty-faced and olive finches are now treated as sister species.Cadena, C. D., J. Klicka and R. E. Ricklefs. (2007). "Evolutionary differentiation in the Neotropical montane region: molecular phylogenetics and phylogeography of Buarremon brush-finches (Aves, Emberizidae)." Molecular Phylogenetics and Evolution. 44(3): 993-1016.
The sooty-faced finch is monotypic.
Description
The sooty-faced finch is long and weighs . The sexes have the same plumage. Adults have a rusty crown and a white down-sweeping "moustache" on an otherwise blackish gray head and nape. Their upperparts are dark olive-green and their wings and tail a slightly browner olive-green. Their upper breast, sides, and flanks are dark olive-green and their lower breast and belly yellow. They have a dark brown or chocolate-brown iris, a dark gray maxilla, a pale yellow or whitish mandible, and dark legs and feet. Juveniles are mostly rich olive-brown with a black-smudged dull yellow belly.Rising, J. D. and A. Jaramillo (2020). Sooty-faced Finch (Arremon crassirostris), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.soffin1.01 retrieved May 8, 2026
Distribution and habitat
The sooty-faced finch is found primarily in Costa Rica and Panama. In them ranges from the Cordillera de Tilarán in Costa Rica's northern San José Province south along the Cordillera de Talamanca into Panama as far as Coclé Province. It also has a small population on Cerro Tacarcuna that straddles the Panama-Colombia border. It inhabits montane evergreen forest in the subtropical and lower temperate zones. There it favors dense undergrowth, especially in ravines and along streams. Sources differ on its elevation range. An older one states that it overall ranges between and a much more recent one says between . In most of its Costa Rican range it is found between but on the Pacific slope of the northern Cordillera de Talamanca is found between .
Behavior Movement
The sooty-faced finch is a year-round resident.
Feeding
The sooty-faced finch feeds on insects, spiders, and berries. It forages on or near the ground, flicking its wings and tail as it hops along. It sometimes attends army ant swarms.
Breeding
Only one sooty-faced finch nest is known; it was found in May 1993 in Costa Rica. It was a dome made from moss, fern leaves, and Selaginella spike-moss and lined with bamboo leaves and fern rootlets. It had a side entrance. It was attached to a fern stem about above the ground. It held two eggs that were ivory-colored with vinaceous-pinkish spots and speckles. The incubation period, time to fledging, and details of parental care are not known.
Vocalization
One sooty-faced finch song is a "high-pitched, thin, emphatic pseee-psééét". Another is a "high-pitched, thin whistled see see seeya sue sue sisi see". Its call is a "sharp, thin, whistled pu-pee".
Status
The IUCN has assessed the sooty-faced finch as being of Least Concern. It has a restricted range; its estimated population of at least 50,000 mature individuals is believed to be decreasing. No immediate threats have been identified. It is considered "frequent to common" overall. It is fairly common in most of its Costa Rican range but rare on the Pacific slope of the northern Cordillera de Talamanca. It is "very local" on Cerro Tacarcuna.
References