Welcome to The Vireo Home Page. This is intended to be a resource for those interested in learning some of the basics about members of the vireo family and aspects of their natural history. I'll be adding information occasionally so check back. I also include links to other sites that provide information about vireos. If you know of any others, please let me know.
The vireo family is a group of exclusively New-World birds, mostly residing in the Nearctic and tropics. In general vireos are rather small, nondescript (vireo is from the Latin word for "greenish"), mostly yellowish or greenish with varying amounts of gray, black or white. Most rely primarily on insects and arthropods for food, and incessantly search dense foliage in various layers for food. Most species in the four genera are found in northern South America, Central America or Mexico, and most are non-migratory. A handful of species, in the genus Vireo, migrate into the United States during the breeding season. These species breeding in North America are the most familiar. But these migrants comprise only a subset of the vireo family.
As if to compensate for a crypic lifestyle and cryptic habitat, many species of vireos are notable for their vocal complexity. Most species have repertoires consisting of many songs, ranging from about a dozen to over 100 in some species. Many are persistent singers, delivering songs throughout the day. A number of species show contextual variation in their delivery of songs. Examples of songs from different vireo species can be found on my songs page. The vireo family has a number of species that are good choices for studies of vocal communication, and the varity of vocal behaviors seen/heard offers considerable opportunity for studies of function and evolution of vocal signals.
The nesting behavior and chronology are known primarily from the species that breed in The United States and Canada. The behavior and nesting of the nonmigratory species, especially the greenlets, are very poorly known. They are all very cryptic and secretive, and difficult to study. The vireos all build what is called a pensive nest, which is attached to branches and hangs below. A couple of nest pictures can be seen in the pictures on the songs page. A generalized nesting pattern can be described for the migratory species. After their arrival on the breeding grounds in the spring, pairs form quickly and the birds soon begin by selecting a nest site. This is usually a small horizontal "Y"-shaped branch, just about the size you can form by spreading out your index and middle fingers into a "Y". The size is carefully chosen, usually by the female, who can be seen perching on likely "Y" branches and pivoting as if to size up the spot. Different species nest at different heights, with Bell's and White-eyed vireos nesting just a few feet off the ground, and Red-eyed and Philadelphia vireos usually nesting high in trees. The pair begins by collecting spider and silkworm webbing, packing into a loose nest blob at the site. As it takes shape, the female begins to form a cup by using her body, sitting in/on the material. As it takes shape, the pair starts to add plant matter including bark fragments, grass, moss, paper from wasp nests and the like. After about a week of work, the final step is to line the nest with fine grass, rootlets, and animal hair. In some species both parents help with the nest, in others, only the female. After building, the female lays one egg per day, usually in early morning, until all are laid, usually 3 or 4. The pair takes turns incubating the eggs for about 12-14 days, and feed the nestlings a variety of insects for about 9-11 days. When the birds leave the nest, they are not very good fliers, but can scramble quite effectively in scrubby growth. The parents continue to feed the fledglings for up to three weeks. After the first nest of the season, the pair usually resets and nests a second, or even perhaps a third time. Most of the nests in any given year are unsuccessful, falling prey to any of the many predators who find the tiny sitting-duck (or rather sitting vireo) eggs or nestlings a nice high-protein meal. Nest predators include snakes and lizards, both small and larger mammals, including racoons, skunks, chipmunks and mice, and oppossums, other birds such as jays, and even ants. The vireos are also the frequent target of cowbirds, who lay their eggs in other species' nests. The cowbird eggs hatch before the vireos and the parents begin feeding those young. The neglected vireo eggs then usually don't hatch. Over the course of the summer the young vireos become more independent, and eventually wander off on their own. The adults and young migrate separately. The birds then migrate to their wintering grounds, and return to the breeding grounds the following spring, to an available area suitable for their habitat needs. They find a mate, and the cycle begins again.The family can roughly be divided into three groups: The true vireos (genus Vireo), the greenlets (genus Hylophilus), and the peppershrikes and shrike-vireos (genera Cyclarhis and Vireolanius). The several species that nest in North America are in the vireo genus; the other two groups have no representatives north of the Mexican/United States border. The Vireo genus can be further divided on the basis of plumage morphology into those with wingbars and eye-rings (e.g. V. griseus and solitarius) and those with plain wings and eye stripes (e.g. V. olivaceus and gilvus). Alternatively, the vireo genus might be divided behaviorally on the basis of those species that tend toward arboreal habits (e.g. V. olivaceus and solitarius) and those that inhabit scrubby or successional growth (e.g. V. griseus and V. bellii).
Compiled from several sources.
Cyclarhis
Cyclarhis gujanensis Rufous-browed Peppershrike.
Cyclarhis nigrirostris Black-billed Peppershrike.
Vireolanius
Vireolanius melitophrys Chestnut-sided Shrike-Vireo.
Vireolanius pulchellus Green Shrike-Vireo.
Vireolanius eximius Yellow-browed Shrike-Vireo.
Vireolanius leucotis Slaty-capped Shrike-Vireo.
Vireo
Vireo brevipennis Slaty Vireo.
Vireo griseus White-eyed Vireo.
Vireo crassirostris Thick-billed Vireo.
Vireo pallens Mangrove Vireo.
Vireo bairdi Cozumel Vireo.
Vireo caribaeus St. Andrew Vireo.
Vireo modestus Jamaican Vireo.
Vireo gundlachii Cuban Vireo.
Vireo latimeri Puerto Rican Vireo.
Vireo nanus Flat-billed Vireo.
Vireo bellii Bell's Vireo.
Vireo atricapillus Black-capped Vireo.
Vireo nelsoni Dwarf Vireo.
Vireo vicinior Gray Vireo.
Vireo osburni Blue Mountain Vireo.
Vireo flavifrons Yellow-throated Vireo.
Vireo plumbeus Plumbeous Vireo.
Vireo cassinii Cassin's Vireo.
Vireo solitarius Blue-headed Vireo.
Vireo carmioli Yellow-winged Vireo.
Vireo huttoni Hutton's Vireo.
Vireo hypochryseus Golden Vireo.
Vireo gilvus Warbling Vireo.
Vireo swainsonii Western Warbling Vireo.
Vireo leucophrys Brown-capped Vireo.
Vireo philadelphicus Philadelphia Vireo.
Vireo olivaceus Red-eyed Vireo.
Vireo flavoviridis Yellow-green Vireo.
Vireo gracilirostris Noronha Vireo.
Vireo altiloquus Black-whiskered Vireo.
Vireo magister Yucatan Vireo.
Vireo masteri Choco Vireo
Hylophilus
Hylophilus poicilotis Rufous-crowned Greenlet.
Hylophilus thoracicus Lemon-chested Greenlet.
Hylophilus semicinereus Gray-chested Greenlet.
Hylophilus pectoralis Ashy-headed Greenlet.
Hylophilus amaurocephalus Grey-eyed Greenlet.
Hylophilus sclateri Tepui Greenlet.
Hylophilus muscicapinus Buff-chested Greenlet.
Hylophilus brunneiceps Brown-headed Greenlet.
Hylophilus hypoxanthus Dusky-capped Greenlet.
Hylophilus semibrunneus Rufous-naped Greenlet.
Hylophilus aurantiifrons Golden-fronted Greenlet.
Hylophilus flavipes Scrub Greenlet.
Hylophilus ochraceiceps Tawny-crowned Greenlet.
Hylophilus decurtatus Lesser Greenlet.
Links to Vireo-related Locations on the Web
Zoonomen: Zoological Nomenclature Resource
Includes Taxonomic listing for all birds!
The United States Geological Survey hosts the Breeding Bird Survey (BBS), source of
distribution and abundance information for all North American birds. Their
site has lots of information on all bird species, including natural history
information and maps of BBS results. They have individual listings for vireo
species breeding in North America, including:
White-eyed vireo Vireo griseus
Bell's vireo Vireo bellii
Gray vireo Vireo vicinior
Solitary vireo Vireo solitarius
Yellow-throated vireo Vireo flavifrons
Hutton's vireo Vireo huttoni
Warbling vireo Vireo gilvus
Philadelphia vireo Vireo philadelphicus
Red-eyed vireo Vireo olivaceus
Audubon Watchlist-- Species of concern with profiles and information:
Bell's Vireo
Gray Vireo
Endangered Species Information SystemFish and Wildlife Information Exchange at VA Tech.
Least Bell's Vireo Listing
Black-capped Vireo Listing
Texas Park and Wildlife Vireo Listing
Island Resource FoundationThreatened and Endangered Birds of the Insular Caribbean
listing for The SAN ANDRES VIREO Vireo caribaeus
Illinois Breeding Bird Atlas: Includes several Vireo Species
Mining Company Vireo listing with vireo-related links.
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