Vireonidae – Vireos, Greenlets & Shrike-babblers

The Vireonidae (Vireos, Greenlets and others) make up a family of small to medium-sized passerines restricted to the New World – until recent DNA studies show two genera in the Old-World. ‘Vireo’ is a Latin word referring to a green migratory bird, perhaps the female Golden Oriole, possibly the European Greenfinch.

Traditionally the family was considered to include four New World genera containing the Vireo (true vireos), Hylophilus (Greenlets), Vireolanius (Shrike-vireos) and Cyclarhis (Peppershrikes). However, phylogenetic studies found Hylophilus to be polyphyletic, with the greenlets split into three distinct groups: the ‘scrub’ greenlets in a restricted Hylophilus, the ‘canopy’ greenlets in resurrected genus Pachysylvia and the tawny-crowned greenlet in new genus Tunchiornis.

In addition, biochemical studies have identified two babbler genera (Pteruthius and Erpornis) which may be Old World members of this family. Observers have commented on the vireo-like behaviour of the Pteruthius shrike-babblers, but apparently no-one suspected the bio-geographically unlikely possibility of vireo relatives in Asia. Some recent taxonomic treatments, such as the IOC taxonomy and combined AviList followed here, include Pteruthius and Erpornis in Vireionidae, whereas other place them in their own families Pteruthidae and Erpornidae.

Red-eyed Vireo Vireo olivaceus

Blue-headed Vireo Vireo solitarius

They are typically dull-plumaged and greenish in colour, the smaller species resembling wood warblers apart from their heavier bills. They range in size from the Chocó Vireo, Dwarf Vireo and Lesser Greenlet, all at around ten centimetres and eight grams, to the peppershrikes and shrike-vireos at up to seventeen centimetres and forty grams.

Ashy-headed Greenlet Hylophilus pectoralis

Buff-cheeked Greenlet Pachysylvia muscicapina

Males of most species are persistent singers. Songs are usually rather simple, monotonous in some species of the Caribbean littoral and islands, and most elaborate and pleasant to human ears in the Chocó vireo and the peppershrikes.

Grey Vireo Vireo vicinior

Chestnut-sided Shrike-Vireo Vireolanius melitophrys

Most species are found in Middle America and northern South America. Thirteen species of true vireos occur farther north, in the United States, Bermuda and Canada; of these all but Hutton’s Vireo are migratory. Members of the family seldom fly long distances except in migration. A few species in the genus Vireo have appeared on the eastern side of the Atlantic as vagrants to the Western Palearctic, the most frequent being Red-eyed Vireo. They inhabit forest environments, with different species preferring forest canopies, undergrowth, or mangrove swamps.

Clicking Shrike-babbler Pteruthius intermedius

Slaty Vireo Vireo brevipennis

The resident species occur in pairs or family groups that maintain territories all year (except Hutton’s Vireo, which joins mixed feeding flocks). Most of the migrants defend winter territories against conspecifics. The exceptions are the complex comprising the Red-eyed Vireo, the Yellow-green Vireo, the Black-whiskered Vireo, and the Yucatan Vireo, which winter in small wandering flocks.

Black-capped Vireo Vireo atricapilla

Golden Vireo Vireo hypochryseus

The nests of many tropical species are unknown. Of those that are known, all build a cup-shaped nest that hangs from branches. The female does most of the incubation, spelled by the male except in the Red-eyed Vireo complex.

All members of the family eat some fruit, but mostly consume insects and other arthropods. They take prey from leaves and branches; true vireos also catch insects in flight, and the Grey Vireo takes around five percent of its prey from the ground.