In migratory populations, most warbling vireos arrive on the breeding grounds from mid-April to Mid-May and most have already formed pairs. Nest construction begins 2 to 7 days after arrival or pair formation on the breeding grounds. Nests are built by both males and females (though more-so by females) and are typically located high in the canopy, but height can range from 1 to 37 m. Like most vireos, they form a deep, hanging cup secured in a forked branch. Construction lasts 6 to 7 days and pairs incorporate leaves, grass, bark strips, pine needles, feathers or hair into the nest. Females lay an average clutch size of 4, white eggs which are spotted with brown or black. Eggs measure 19 mm in length. Incubation lasts 12 days on average, and the young fledge after 13 to 14 days. Parents continue to feed their fledglings for at least 2 weeks post-fledge, but exact independence date is unknown. Age at reproductive maturity is unknown but is presumed to be approximately 10 months or during an individual's first spring. In locations with long breeding seasons, two broods have been reported. (Ehrlich, et al., 1988; Gardali and Ballard, 2000)
Territory size ranges from 1.2 to 3 hectares. Size is likely influenced by population density and habitat quality. Warbling vireos defend their territories but do not often use physical contact to deter intruders. They have been observed tolerating red-eyed vireos and yellow-throated vireos that sing within their territories. (Gardali and Ballard, 2000; James, 1976)
Like all birds, (Gardali and Ballard, 2000)perceives its environment through visual, auditory, chemical and tactile stimuli. Vocal communications include male territorial song, courtship call, and a variety of contact, begging, and warning calls. The typical song is mnemonically described as "If I see you, I will seize you, and I'll squeeze you 'til you squirt!". Compared to other vireos, this call is undulating and more connected with an overall warbling quality. Calls are used between mates to locate each other, as well as warn of nearby predators. Pairs also use body postures to communicate during courtship. Male courtship begins with an aerial chase of the female which is followed by a stationary interaction where the male fans his tail and turns his body back and forth. The female responds with wing-quivering and will eventually peck at the male's beak when he approaches.
Lepidoptera), true bugs (Hemiptera), ladybug beetles (Coccinellidae), beetles (Coleoptera), as well as spiders (Arachnida). Non-insect items consumed include elderberries and poison oak berries. (Ehrlich, et al., 1988; Gardali and Ballard, 2000; James, 1976)is primarily an insectivore but will also consume spiders and berries in the fall and winter. They utilize a hover and glean feeding strategy, and capture nearly all of their food from peripheral leaves of trees or shrubs. Prey items include caterpillars and pupae of butterflies and moths (
Currently there have been no observations of adult or nest predation, though it is known to occur. Certain bird species are heavily mobbed by Steller’s jays, western scrub-jays, blue jays and common grackles. Western mammalian predators include red squirrels and western gray squirrels. Their dull, olive-gray coloration likely serves as camouflage in the tree canopy. (Gardali and Ballard, 2000; Gardali and Ballard, 2000)and are presumed to be predators. These species include
brown-headed cowbirds and have not evolved any method to remove or destroy the foreign eggs. During fall and winter, these birds include berries in their diets, and may serve a small role as a local seed disperser. One individual has been reported to have have been captured with feather mites of the genus Proctophyllodes. (Ehrlich, et al., 1988; Gardali and Ballard, 2000; Ortega and Ortega, 2003)is primarily an insectivore that likely impacts local prey populations. They are common hosts of brood parasitic
There are no known adverse effects of warbling vireos on humans.
brown-headed cowbird brood parasitism. Warbling vireos have not yet evolved a method to identify, remove or destroy cowbird eggs which results in low productivity and may cause future population declines. Another concern is pesticide application, as warbling vireo populations may become locally extinct after foraging and nesting trees are sprayed. (Ehrlich, et al., 1988; Gardali and Ballard, 2000)is of least concern to the IUCN Red List as it has a large population size dispersed across a wide geographic range. As migratory birds, they are protected under the United States Migratory Bird Act. This species prefers forested habitats with significant portions of canopy openings and may thrive as a result of careful selective harvesting by the logging industry. There is a minor concern with regards to the effect of
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.
Referring to an animal that lives in trees; tree-climbing.
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
active at dawn and dusk
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
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
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).
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
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.
living in cities and large towns, landscapes dominated by human structures and activity.
uses sight to communicate
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.
Gardali, T., G. Ballard. 2000. "The Birds of North America Online" (On-line). Vireo gilvus. Accessed March 28, 2011 at http://bna.birds.cornell.edu/bna/species/551 doi:10.2173/bna.551.
Gardali, T., G. Ballard, N. Nur, G. Geupel. 2000. Demography of a declining population of warbling vireos in coastal California. The Condor, 102: 601-609. Accessed March 29, 2011 at http://www.prbo.org/cms/docs/terre/Gardali%20et%20al.%202000.pdf.
James, R. 1976. Foraging Behavior and Habitat Selection of Three Species of Vireos in Southern Ontario. The Wilson Bulletin, 88/1: 62-75.
Ortega, C., J. Ortega. 2003. Brown-headed cowbird (Molothrus ater) parasitism on warbling vireos (Vireo gilvus) in southwest Colorado. The Auk, 120/3: 759-764. Accessed March 29, 2011 at http://www.colostate.edu/depts/sjbrc/pubs/BrownHeadedCowbirdsParasitism.pdf.
Sibley, D. 2000. The Sibley Guide to Birds. New York: Alfred A. Knopf, Inc..