Choco Vireo vs Delacour's langur

Vireo masteri compared with Trachypithecus delacouri

Key Differences

• Choco Vireo is Endangered while Delacour's langur is Critically Endangered.

Taxonomic Classification

Rank	Choco Vireo	Delacour's langur
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Aves (Birds)	Mammalia (Mammals)
Order	Passeriformes (Songbirds)	Primates (Primates)
Family	Vireonidae	Cercopithecidae (Old World Monkeys)
Genus	Vireo	Trachypithecus
Species	Vireo masteri	Trachypithecus delacouri

Evolutionary Relationship

Choco Vireo and Delacour's langur share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Choco Vireo

EN — Endangered

Delacour's langur

CR — Critically Endangered

Physical Characteristics

Attribute	Choco Vireo	Delacour's langur
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Choco Vireo

Habitat

Found across multiple habitat types including tropical and subtropical dry broadleaf forests, flooded grasslands and savannas, and montane grasslands and shrublands, among 4 distinct biome types within the Neotropic biogeographic realm.

Range

Distributed across Colombia, Ecuador, and Norway. Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

Delacour's langur

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Choco Vireo

The Choco Vireo (Vireo masteri) is a small, poorly known passerine in the family Vireonidae, with a highly restricted range in the western Andes foothills on the Pacific slope of Colombia and possibly adjacent Ecuador. It was described scientifically only in 1997, reflecting the challenges of survey work in the remote, wet, and botanically complex terrain of the Colombian Chocó. The Choco Vireo is a small greenish-yellow vireo with a distinctive facial pattern including a pale supercilium and dark eye-stripe. Like other vireos, it forages methodically through mid-canopy and sub-canopy foliage, gleaning caterpillars, beetles, and other invertebrates from leaves. Its song is a series of high, slurred phrases repeated with characteristic vireonid persistence. The species appears restricted to humid montane and foothill forest at elevations roughly between 800 and 1,800 metres — a zone severely impacted by the expansion of coca cultivation, illegal logging, and cattle ranching in the Colombian Pacific region. The IUCN classifies the Choco Vireo as Endangered given its extremely small and severely fragmented range and continued loss of suitable forest habitat. Very little is known about its population size, ecology, or breeding biology, making targeted survey and monitoring urgently needed.