Vireo griseus relies heavily on acoustic and visual forms of communication. The primary call of this species has an explosive quality and may be described mnemonically as "quick-with-the-beer-check." Both the first and last notes are short and sharp, while the middle notes are a rapid warble. This song is given by males during the breeding season to establish territory and attract females. Fledgling males learn their father's song very early in life, and may begin mimicking his call as early as one month after leaving the nest. Young Vireo griseus may also develop some elements of their song by mimicking their neighbors. Both males and females give a harsh chattering call in response to predators or in territorial encounters between males. Within a mated pair, both also give short 'pik' contact calls to each other when nearby. Adults and nestlings that are several days old will emit a harsh squeal if captured and handled by humans (during banding) and likely serves to startle a predator or alert a mate.
Vireo griseus also uses body postures and behaviors to communicate, which may be done with or without vocal accompaniment. Alert, anxious individuals may perform exaggerated neck movements or wing flicks. These movements likely serve to intimidate predators or territorial intruders. Other warning behaviors include pecking at a nearby perch or their own feet. If the threat does not retreat, these vireos will perform an aerial attack.
Like most birds, Vireo griseus perceives its environment through auditory, visual, tactile and chemical stimuli.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
The International Union for Conservation of Nature and Natural Resources (IUCN) currently considers Vireo griseus to be of least concern. This is due to the large population size, current increasing trend in population numbers, and relatively large geographical range. Although stable now, this species may be threatened by habitat loss in the future. The shrubby habitats that Vireo griseus prefers are often easy targets for human development including urbanization and conversion to agricultural fields.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of Vireo griseus on humans.
Vireo griseus has no known economic impacts on humans.
Vireo griseus serves as predator, prey, and seed dispersant within the ecosystems it inhabits. This species is largely insectivorous, particularly during the breeding season. These feeding habits likely have a significant impact on local insect communities, especially populations of Lepidoptera which are the preferred prey. During the non-breeding season Vireo griseus consumes mostly fruit and is likely an important seed dispersant for many plant species. Vireo griseus has a strong relationship with one fruit-bearing species, Bursera simaruba, and is the primary seed dispersant. Vireo griseus remains highly territorial during the non-breeding season and is known to aggressively defend Bursera simaruba plants in particular. The eggs and young of Vireo griseus are also prey for a variety of predators.
The diet of Vireo griseus varies seasonally, as it is primarily insectivorous during the breeding season and frugivorous during the non-breeding season. When foraging for insects, this species often perches motionless and tilts its head to visually locate and watch prey before acting. This is a foliage gleaning species, and after locating a prey item it will capture prey by hovering, hanging, lunging or picking. Caterpillars are preferred prey items, but Vireo griseus may also consume flies, spiders and their egg cases, damselflies, mayflies, beetles, cockroaches, stink bugs, leafhoppers, lacewings, bees, ants, and wasps, and grasshoppers.
During the non-breeding season, Vireo griseus consumes a wide variety of insects but is mostly frugivorous. This species has a very strong relationship with Bursera simaruba trees and is the primary seed dispersant. Unlike many species, Vireo griseus establishes territory during the non-breeding season and Bursera simaruba trees are often aggressively guarded. Across wintering regions, Vireo griseus may consume the fruit of sumac, dogwood, poison ivy, pokeweed, and waxmyrtle as well as wild grapes.
Animal Foods: insects
Plant Foods: fruit
Primary Diet: carnivore (Insectivore )
Vireo griseus is a Neotropical migrant that inhabits both the Nearctic and Neotropical regions. During the breeding season in the spring and summer months, these birds inhabit the southeastern United States and northeast Mexico. The northern extent of their range stretches from southern Iowa, across southern Michigan and to southern Massachusetts. They travel as far west as eastern Nebraska, Oklahoma and Texas. They are year-round residents along the southeast coastal United States from South Carolina to Texas, and also down through the east coast of Mexico. White-eyed vireos also overwinter in southern Mexico, Belize, Guatemala, Cuba, the Cayman Islands and the Bahamas.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Vireo griseus prefers brushy habitats defined by a dense understory layer, and generally located near a water source. They often inhabit abandoned agricultural fields that have lain fallow for 20 to 50 years to allow for adequate shrubby successional vegetation to grow. White-eyed vireos are frequently found in thickets alongside marshes and are one of the most prevalent avian species in the Central Everglades. In this region, white-eyed vireos prefer "bayhead" areas which are dominated by red bay (Persea borbonia), sweet bay (Magnolia virginiana), dahoon holly (Ilex cassine), and wax myrtle (Myrica cerifera).
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: forest
Wetlands: marsh
Other Habitat Features: agricultural ; riparian
Lifespan for Vireo griseus is currently unknown. Adult survivorship ranges from 15 to over 57% depending on environmental conditions. First year survivorship is unknown. Possible causes of mortality include nest predation and severe weather.
Vireo griseus is a small, stocky vireo measuring 12.7 cm in length, with a 19 cm wingspan and weighing 11.5 g. They have dark olive backs, with darker, almost black wings and tails. They have two white wingbars and white to yellow edges on the primaries. The nape is gray and borders an olive-colored head. One of the most defining features of this vireo are the bright yellow "spectacles" that include the lores and surround the eyes. True to the common name, another identifying feature are the white irises that they develop as adults. They have whitish throats and undersides with pale yellow flanks and undertail coverts. Beaks and legs are black. Juveniles exhibit dark irises which will retain this coloration through their first year. Juveniles may also be identified by white "spectacles", an entirely pale gray head and overall paler plumage. This species displays no sexual dimorphism.
Average mass: 11.5 g.
Average length: 12.7 cm.
Average wingspan: 19.0 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Specific predators of Vireo griseus have rarely been documented. Most predation occurs during the breeding season as eggs and nestlings are abundant and make easy prey. Hypothesized predators include snakes, mice, chipmunks, blue Jays, raccoons, skunks, and opossums. There is very little evidence for predation of adults, but one case has been documented of adult capture and consumption by a short-tailed hawk in Florida.
When predators are near a nest, the Vireo griseus pair will emit harsh, rapid chattering. Adults will also peck at their perch or feet which may precede an aerial attack if the intruder does not retreat.
Known Predators:
Like all vireos, Vireo griseus is monogamous. Males establish territories and females visit several and eventually select a suitable mate. There are no specific courtship displays, but pairs appear to court each other for several days during which time they forage together with the male closely following the female. Pair bonds seem to last only one season.
Mating System: monogamous
Vireo griseus individuals breed once a year during the breeding season which lasts from late April to early August. Once pairs have formed, they begin searching for a nesting site which is usually less than 1 m from the ground in dense vegetation. Females select the site, while the males follow close behind. They usually select a suitable, forked branch where they can construct a suspended, cup-shaped nest. Both participate in nest building and they collect spiderweb silk, twigs, bark strips, and grass to incorporate into the nest. This process takes 3 to 5 days to complete. The female typically lays 4 eggs, and will lay one per day starting 1 to 3 days after the nest is complete. Incubation is done by both parents and will last 13 to 15 days. After the young hatch, they will fledge after 9 to 11 days and will be brooded by their parents for an additional 23 days at most. White-eyed vireos can breed during their first spring, though not all are successful.
Breeding interval: White-eyed vireos breed once yearly.
Breeding season: White-eyed vireos breed from April through August.
Range eggs per season: 3 to 5.
Range time to hatching: 13 to 15 days.
Range fledging age: 9 to 11 days.
Range time to independence: 23 (high) days.
Average age at sexual or reproductive maturity (female): <1 years.
Average age at sexual or reproductive maturity (male): <1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
After selecting a suitable nesting site and constructing a secure nest for their young, both parents participate in incubating the clutch. After hatching, the altricial young require constant feeding and brooding, again by both parents. Male and female white-eyed vireos develop brood patches, though the male's is not vascularized. Parents continue to brood their young throughout the nestling and fledgling periods, which may last up to 34 days total.
Parental Investment: altricial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)
