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. (Hopp, et al., 1995; Sibley, 2000)
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). (Ehrlich, et al., 1988; Gawlik and Rocque, 1998; Hopp, et al., 1995)
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. (Sibley, 2000)
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. (Ehrlich, et al., 1988; Hopp, et al., 1995)
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. (Ehrlich, et al., 1988; Hopp, et al., 1995)
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. (Ehrlich, et al., 1988; Hopp, et al., 1995)
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. (Hopp, et al., 1995)
Vireo griseus is largely a migratory species that performs two annual journeys: north to the North American breeding grounds in the spring, and south to the wintering grounds in Central America in the fall. Non-migratory populations remain year-round in southern coastal regions of the United States from South Carolina to Texas, and also along the Gulf Coast of Mexico. Although they make long-distance journeys at night, like many migratory birds, they are diurnal species for the remainder of the year.
Vireo griseus is a highly territorial species and remains so even throughout the winter and against other species. Males exhibit territorial behaviors against other males during the breeding season. On their wintering grounds, both males and females may defend small territories and are particularly defensive of their preferred food source, Bursera trees. However, during migrations this species may be seen in both inter- and intraspecies flocks. (Greenberg, 1992; Hopp, et al., 1995)
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.
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. (Greenberg, et al., 1995; Hopp, et al., 1995)
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. (Hopp, et al., 1995)
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. (Greenberg, et al., 1995; Hopp, et al., 1995)
Vireo griseus has no known economic impacts on humans.
There are no known adverse effects of Vireo griseus on humans.
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. ("Vireo griseus", 2009; Hopp, et al., 1995)
Rachelle Sterling (author), Special Projects, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
marshes are wetland areas often dominated by grasses and reeds.
makes seasonal movements between breeding and wintering grounds
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
Birdlife International. 2009. "Vireo griseus" (On-line). IUCN Red List of Threatened Species. Accessed June 07, 2011 at http://www.iucnredlist.org/apps/redlist/details/146454/0.
Bradley, R. 1980. Vocal and territorial behavior in the White-eyed Vireo. The Wilson Bulletin, 92/3: 302-311.
Ehrlich, P., D. Dobkin, D. Wheye. 1988. The Birder's Handbook: A Field Guide to the Natural History of North American Birds. New York, New York: Simon and Schuster.
Gawlik, D., D. Rocque. 1998. Avian communities in bayheads, willowheads, and sawgrass marshes of the Central Everglades. Wilson Bulletin, 110/1: 45-55. Accessed March 30, 2011 at http://elibrary.unm.edu/sora/Wilson/v110n01/p0045-p0055.pdf.
Greenberg, R. 1992. Ecology and conservation of neotropical migrant landbirds.. Washington, DC: Smithsonian Institution Press.
Greenberg, R., M. Foster, L. Marquez-Valdelamar. 1995. The role of the white-eyed vireo in the dispersal of Bursera fruit on the Yucatan Peninsula. Journal of Tropical Ecology, 11: 619-639.
Hopp, S., A. Kirby, C. Boone. 1995. "The Birds of North America Online" (On-line). Vireo griseus. Accessed March 30, 2011 at http://bna.birds.cornell.edu/bna/species/168.
Sibley, D. 2000. The Sibley Guide to Birds. New York: Alfred A. Knopf, Inc..