Yellow-green Vireo

The Yellow-green Vireo, Vireo flavoviridis, is a small passerine bird, a vibrant blend of olive-green and yellow hues. Adults typically measure between 14 to 14.7 cm in length and weigh around 18.5 grams. They are characterized by olive-green upperparts and a dusky-edged gray crown. A distinctive dark line extends from the bill to the red-brown eyes, complemented by a striking white supercilium. The underparts are predominantly white, with a touch of yellow on the breast sides and flanks. Juveniles present a more subdued appearance with brown eyes, a brownish back, and less pronounced yellow on the underparts.

Identification Tips

To distinguish the Yellow-green Vireo from its close relative, the Red-eyed Vireo, look for the Yellow-green's more vividly yellow underparts, a less defined gray crown without a black border, and a different eye color. The upperparts are also a more pronounced yellow. However, some individuals may be challenging to differentiate, even when observed closely.

Habitat

This species is found in the canopy and middle levels of light woodland, forest edges, and gardens. It thrives at altitudes ranging from sea level to 1500 meters.

Distribution

The Yellow-green Vireo breeds from Mexico to Panama, with occasional sightings in southern Texas, USA. It is a migratory bird, spending winters in the northern and eastern Andes and the western Amazon Basin.

Behaviour

The Yellow-green Vireo is a migratory species, with breeding birds returning to Central America from early February to March. They typically depart southwards by mid-October. During the breeding season, they are known for their industrious nest-building and attentive care for their young.

Song & Calls

The call of the Yellow-green Vireo is a nasal "nyaaah," while its song is a repetitive and rhythmic "veree veer viree, fee’er vireo viree." This song is shorter and faster than that of the Red-eyed Vireo and is infrequently heard on its wintering grounds.

Breeding

The female constructs a 6.5-cm-wide cup nest from various plant materials, securing it to a sturdy twig typically 1.5–3.5 m above ground, though sometimes as high as 12 m. The clutch usually consists of two or three brown-marked white eggs, laid from March to June. The female incubates the eggs alone, but both parents participate in feeding the chicks.

Diet and Feeding

Yellow-green Vireos primarily feed on insects gleaned from tree foliage, with a preference for caterpillars and beetles. They also consume small fruits, such as mistletoe berries, and in their winter habitat, they may eat fruits from Cymbopetalum mayanum and gumbo-limbo trees.

Conservation status

The Yellow-green Vireo is currently listed as Least Concern by the IUCN, indicating that it does not face any immediate threat of extinction.