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Home/Species/ Bullock's Oriole

Icterus bullockiorum

(Swainson, 1827)

Bullock's Oriole

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G5SecureGlobal Rank
Least concernIUCN
Identity
Unique IDELEMENT_GLOBAL.2.102107
Element CodeABPBXB9220
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAves
OrderPasseriformes
FamilyIcteridae
GenusIcterus
Synonyms
Icterus bullockii(Swainson, 1827)Icterus galbula bullockii
Other Common Names
Bolsero Calandria (ES) Oriole de Bullock (FR)
Concept Reference
American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Taxonomic Comments
Formerly considered conspecific with I. galbula and I. abeillei under the name I. galbula (Northern Oriole) but resplit into separate species by AOU (1995). See AOU (1995, 1998) for a brief summary of the bases for the split.

According to AviList (2025), "Swainson’s (1827) original spelling was bullockii in the singular, but he made it clear that it referred to two Bullocks (father and son). There is currently great heterogeneity in the way various zoological disciplines deal with such issues. While the original spelling remains preserved in many animal groups, the prevalent ornithological practice is to change endings to reflect the correct grammatical circumstances, as is done herein by adopting "bullockiorum". The upcoming fifth edition of the ICZN Code will introduce standardization into this heterogeneity, which may or may not be in agreement with the position taken herein."
Conservation Status
Rank MethodExpertise without calculation
Review Date2016-04-08
Change Date1996-12-04
Range Extent Comments
BREEDS: southern interior British Columbia, southern Alberta, southwestern Saskatchewan, eastern Montana, southwestern North Dakota, and central South Dakota south (east of coastal areas of Washington and Oregon) to northern Baja California, central Sonora, northern Durango, Coahuila, and central and southern Texas, and east to western Nebraska, western Kansas, and western Oklahoma (AOU 1983). WINTERS: regularly in coastal California, and from southern Sinaloa, the state of Mexico, and Puebla south to Guatemala (casually to northwestern Coasta Rica), in small numbers in the Gulf coast region from Texas to southern Georgia and Florida, and casually north to central California and southern Arizona (AOU 1983). MIGRATES: regularly through western North America west of the Rockies, including Baja California (AOU 1983).
Ecology & Habitat

Habitat

Open woodland, deciduous forest edge, riparian woodland, partly open situations with scattered trees, orchards, shade trees. In migration and winter also in humid forest edge, second growth, and scrub; Nests in trees, average of 8-9 m above ground, usually at end of drooping branch.

Ecology

Thought to be a solitary nester, but tends to aggregate nests (williams 1988). Females foraged regularly more than 200 meters from nest, and up to 1 kilometer away (Williams 1990).

Reproduction

Clutch size is 3-6 (commonly 4-5). Incubation, by female, lats 12-14 days. Young are tended by both parents, leave nest at 12-14 days. Ejects brown-headed cowbird eggs from nest (Sealy and Neudorf 1995, Condor 97:369-375).
Terrestrial Habitats
Woodland - HardwoodShrubland/chaparralSuburban/orchard
Palustrine Habitats
Riparian
Other Nations (2)
CanadaN5B
ProvinceRankNative
SaskatchewanSUBYes
British ColumbiaS5BYes
AlbertaS2BYes
United StatesN5B
ProvinceRankNative
OklahomaSNRBYes
OregonS4BYes
New MexicoS4B,S5NYes
TexasS4BYes
KansasS3BYes
UtahS4BYes
ArizonaS3B,S2MYes
North DakotaSNRBYes
ColoradoS5Yes
MontanaS5BYes
South DakotaS4BYes
WashingtonS4BYes
NebraskaS3BYes
CaliforniaSNRBYes
IdahoS4BYes
WyomingS5B,S5NYes
Navajo NationS3BYes
NevadaS4BYes
References (33)
  1. American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
  2. American Ornithologists' Union (AOU). 1995. Fortieth supplement to the American Ornithologists' Union Check-list of North American Birds. Auk 112:819-30.
  3. American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in <i>The Auk</i>]. Also available online: http://www.aou.org/.
  4. AviList Core Team. 2025. AviList: The Global Avian Checklist, v2025. https://doi.org/10.2173/avilist.v2025
  5. Balda, R. P., and G. C. Bateman. 1971. Flocking and annual cycle of the piñon jay, <i>Gymnorhinus cyanocephalus</i>. Condor 73:287-302.
  6. Bent, A.C. 1958. Life histories of North American blackbirds, orioles, tanagers, and their allies. U.S. National Museum Bulletin 211. Washington, DC.
  7. BirdLife International. 2004b. Threatened birds of the world 2004. CD ROM. BirdLife International, Cambridge, UK.
  8. 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.
  9. Harrison, C. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Cleveland, Ohio.
  10. Harrison, H. H. 1979. A field guide to western birds' nests. Houghton Mifflin Company, Boston. 279 pp.
  11. Horn, H. S. 1968. The adaptive significance of colonial nesting in the Brewer's Blackbird. Ecology 49:682-694.
  12. Howell, S. N. G., and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, Oxford, UK.
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  14. Moore, W. S., and R. A. Dolbeer. 1989. The use of banding recovery data to estimate dispersal rates and gene flow in avian species: case studies in the Red-winged Blackbird and Common Grackle. Condor 91:242-253.
  15. Parker III, T. A., D. F. Stotz, and J. W. Fitzpatrick. 1996. Ecological and distributional databases for neotropical birds. The University of Chicago Press, Chicago.
  16. Peterjohn, B. G., J. R. Sauer, and W. A. Link. 1994. The 1992 and 1993 summary of the North American Breeding Bird Survey. Bird Populations 2:46-61.
  17. Peterson, R.T. 1990b. A field guide to western birds. Houghton Mifflin Company, Boston.
  18. Poole, A. F. and F. B. Gill. 1992. The birds of North America. The American Ornithologists' Union, Washington, D.C. and The Academy of Natural Sciences, Philadelphia, PA.
  19. Raffaele, H. A. 1983a. A guide to the birds of Puerto Rico and the Virgin Islands. Fondo Educativo Interamericano, San Juan, Puerto Rico. 255 pp.
  20. Rohwer, S., and J. Manning. 1990. Differences in timing and number of molts for Baltimore and Bullock's orioles: implications to hybrid fitness and theories of delayed plumage maturation. Condor 92:125-140.
  21. 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.
  22. Scott, S. L. 1983. Field guide to the birds of North America. National Geographic Society, Washington, D.C.
  23. Sealy, S. G. and T. J. Underwood. 2004. Accepters and rejecters of cowbird parasitism in the New World orioles (Icterus spp.). Ornitologia Neotropical 15:331-348.
  24. Sibley, D. A. 2000a. The Sibley guide to birds. Alfred A. Knopf, New York.
  25. 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.
  26. Tarvin, K. A., and G. E. Woolfenden. 1999. Blue Jay (<i>Cyanocitta cristata</i>). No. 469 IN A. Poole and F. Gill, editors. The birds of North America. The Birds of North America, Inc., Philadelphia, PA. 32pp.
  27. Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
  28. Thompson, F. R., III. 1994. Temporal and spatial patterns of breeding brown-headed cowbirds in the midwestern United States. Auk 111:979-990.
  29. Williams, L. 1952b. Breeding behavior of the Brewer blackbird. Condor 54:3-47.
  30. Williams, P. L. 1988d. Spacing behavior and related features of social organization in Northern Orioles of central coastal California. Ph.D. thesis, University of California, Berkeley.
  31. Williams, P. L. 1990d. Use of radiotracking to study foraging in small terrestrial birds. Studies in Avian Biology 13:181-186.
  32. Willson, M. F. 1966. Breeding ecology of the Yellow-headed Blackbird. Ecological Monographs 36:51-77.
  33. Zook, J. L. 2002. Distribution maps of the birds of Nicaragua, Costa Rica, and Panama. Unpublished.