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Home/Species/ Western Warbling-Vireo

Vireo swainsoni

Baird, 1858

Western Warbling-Vireo

GNRUnranked Found in 10 roadless areas NatureServe Explorer →
GNRUnrankedGlobal Rank
Identity
Unique IDELEMENT_GLOBAL.2.1368059
Element CodeABPBW01300
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAves
OrderPasseriformes
FamilyVireonidae
GenusVireo
Concept Reference
American Ornithological Society (AOS). Chesser, R. T., S. M. Billerman, K. J. Burns, C. Cicero, J. L. Dunn, B. E. Hernández-Baños, R. A. Jiménez, O. Johnson, N. A. Mason, and P. C. Rasmussen. 2025. Sixty-sixth Supplement to the American Ornithological Society’s Check-list of North American Birds. Ornithology 142:1-19.
Taxonomic Comments
Formerly (AOU 1983, 1998) considered conspecific with Vireo gilvus, but separated based on concordant differences in a suite of traits, including genetics (Slager et al. 2014; Lovell et al. 2021; Carpenter et al. 2022a, b), morphology (Lovell 2010), song (Lovell 2010, Spencer 2012), molt and migration (Voelker and Rohwer 1998), and response to brood parasitism (Sealy et al. 2000). The two species show low levels of hybridization and cytonuclear discordance across a large area, even where males of the two taxa occupy adjacent territories (Lovell et al. 2021) (AOS 2025).
Ecology & Habitat

Habitat

Open deciduous and mixed deciduous coniferous woodland, coniferous forest interspersed with aspen stands, riparian forest and thickets (commonly in association with cottonwoods, aspen, and tree willows; often near water), pine-oak association, orchards, and parks, in foothills and mountains; in migration and winter, a variety of wooded habitats (Subtropical and Temperate zones) (AOS 2025).

Ecology

Density figures of 13.4 birds/40 ha have been recorded in flatland aspen; 60.0/40 ha in scrub-meadow; 5 pairs/40 ha in Douglas fir forest (Bureau of Land Management, no date). Nests often parasitized by Brown-headed Cowbirds, suffering up to 80% parasitism in some areas; this high rate, combined with the fact that parasitized nests typically produce no vireo young, can create sink populations, even in areas where vireos are common (Ward and Smith 2000).

Reproduction

Male and female, in turn, incubate 4, sometimes 3-5, eggs for about 12 days. Altricial young are tended by both parents, leave the nest in about 12-14 days.
Terrestrial Habitats
Forest - HardwoodForest - MixedWoodland - HardwoodWoodland - MixedSavannaSuburban/orchard
Palustrine Habitats
Riparian
Other Nations (2)
CanadaNNR
ProvinceRankNative
Northwest TerritoriesS5Yes
British ColumbiaS5BYes
Yukon TerritoryS2BYes
SaskatchewanS5BYes
United StatesNNR
ProvinceRankNative
Navajo NationS4BYes
WashingtonS5BYes
New MexicoS4B,S5NYes
NevadaS4BYes
AlaskaS4BYes
ColoradoS5BYes
ArizonaS5Yes
WyomingS5BYes
OregonS5Yes
CaliforniaSNRYes
UtahS4BYes
IdahoS5BYes
Roadless Areas (10)
Arizona (2)
AreaForestAcres
Cdo WsaCoronado National Forest1,955
Sierra Ancha Wilderness ContiguousTonto National Forest7,787
California (1)
AreaForestAcres
Benton RangeInyo National Forest9,637
Colorado (1)
AreaForestAcres
Long ParkRoutt NF42,100
Montana (3)
AreaForestAcres
Freezeout MountainBeaverhead-Deerlodge National Forest97,305
Patricks Knob - North CutoffLolo National Forest16,970
South Siegel - South CutoffLolo National Forest13,474
New Mexico (2)
AreaForestAcres
Mt. TaylorCibola National Forest6,355
South Guadalupe MountainsLincoln National Forest20,930
Washington (1)
AreaForestAcres
Mt. Baker MaMt Baker-Snoqualmie National Forest24,847
References (15)
  1. American Ornithological Society (AOS). Chesser, R. T., S. M. Billerman, K. J. Burns, C. Cicero, J. L. Dunn, B. E. Hernández-Baños, R. A. Jiménez, O. Johnson, N. A. Mason, and P. C. Rasmussen. 2025. Sixty-sixth Supplement to the American Ornithological Society’s Check-list of North American Birds. Ornithology 142:1-19.
  2. American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
  3. Barlow, J.C. 1980. Patterns of ecological interactions among migrant and resident vireos on the wintering grounds. Pages 79-107 in A. Keast and E.S. Morton, editors. Migrant birds in the neotropics: ecology, distribution, and conservation. Smithsonian Institution Press, Washington, DC.
  4. Bureau of Land Management. Life History Summaries.
  5. Droege, S., and J.R. Sauer. 1990. North American Breeding Bird Survey, annual summary, 1989. U.S. Fish and Wildlife Service, Biological Report 90(8). 22 pp.
  6. Hagan, J. M., III, and D. W. Johnston, editors. 1992. Ecology and conservation of neotropical migrant landbirds. Smithsonian Institution Press, Washington, D.C. xiii + 609 pp.
  7. Harrison, C. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Cleveland, Ohio.
  8. Johnson, N. K., R. M. Zink, and J. A. Marten. 1988. Genetic evidence for relationships in the avian family Vireonidae. Condor 90:428-445.
  9. Keast, A., and E.S. Morton. 1980. Migrant birds in the neotropics: ecology, distribution, and conservation. Smithsonian Institution Press, Washington, DC.
  10. Murray, B.W., W.B. McGillivray, and J.C. Barlow. 1994. The use of cytochrome B sequence variation in estimation of phylogeny in the Vireonidae. Condor 96(4):1037-1054.
  11. Sauer, J.R., and S. Droege. 1992. Geographical patterns in population trends of Neotropical migrants in North America. Pages 26-42 in J.M. Hagan, III, and D.W. Johnston, editors. Ecology and conservation of Neotropical migrant landbirds. Smithsonian Institution Press, Washington, DC.
  12. Sibley, C.G., and B.L. Monroe, Jr. 1990. Distribution and Taxonomy of Birds of the World. Yale University Press, New Haven, CT. xxiv + 1111 pp.
  13. Stiles, F. G. and A. F. Skutch. 1989. A guide to the birds of Costa Rica. Cornell University Press, Ithaca, New York, USA. 511 pp.
  14. Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
  15. Ward, D., and J. N. M. Smith. 2000. Brown-headed Cowbird parasitism results in a sink population in Warbling Vireos. Auk 117:337-344.