Smaller (6-7 inches) and darker than the Northern Oriole (Icterus galbula), the male Orchard Oriole is most easily identified by its black upper body, dark orange-brown underparts, and thin white wing bars. The female Orchard Oriole is mostly yellow-green overall with grayish wings with white wing bars. Immature Orchard Orioles resemble females, but young male birds have a solid black throat. The Orchard Oriole breeds widely across the eastern United States and southern Canada from Manitoba and New York south to central Florida and Texas. Smaller numbers breed in central Mexico and along the Mexican Gulf coast. In winter, Orchard Orioles migrate south to southern Mexico, Central America, and northern South America. Orchard Orioles breed in open deciduous forest, usually near water. During the winter, this species inhabits similar kinds of habitat around humid tropical forests. Orchard Orioles primarily eat insects and other invertebrates, adding fruit to their diets when available, particularly in winter. In appropriate habitat, Orchard Orioles may be observed foraging for insects in the branches of trees, often in the tree canopy but sometimes quite close to the ground. This species occasionally visits oriole nectar feeders or hummingbird feeders. Orchard Orioles are primarily active during the day, but, like many migratory songbirds, this species migrates at night.
- Scharf, William C. and Josef Kren. 2010. Orchard Oriole (Icterus spurius), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/255
- Peterson, Roger Tory. Birds of Eastern and Central North America. Boston: Houghton Mifflin, 1980. Print.
- eBird Range Map - Orchard Oriole. eBird. Cornell Lab of Ornithology, N.d. Web. 20 July 2012. http://ebird.org/ebird/map/orcori.
- Icterus spurius. Xeno-canto. Xeno-canto Foundation, n.d. Web. 20 July 2012. http://xeno-canto.org/browse.php?query=Icterus+spurius.
- Orchard Oriole (Icterus spurius). The Internet Bird Collection. Lynx Edicions, n.d. Web. 20 July 2012. http://ibc.lynxeds.com/species/orchard-oriole-icterus-spurius.
Orchard orioles breed in Canada, the United States, and Mexico. Their breeding range extends north to southeast Saskatchewan, through southwest Manitoba, southern Ontario, central New York and extreme southern Maine, along the entire east coast of United States through northern Florida, southwest from the Gulf coast of northern Florida through southern Texas (but absent from Rio Grande Valley), and into inland central Mexico to southern Guanajuato. The breeding range extends west to eastern Montana and Colorado, western Texas, and northwestern Oklahoma.
The winter range of orchard orioles includes both coasts of Mexico, through Central America, and northern South America. On the Pacific Coast they occur north to central Sinaloa and south to central Oaxaca, where they also occur inland. On the Gulf Coast they are found as far north as southern Tamaulipas and south to southern Veracruz, where they are also found inland. Orchard orioles are present on all of the Yucatan Peninsula and throughout Central America except the highlands of Guatemala and southern highlands of Nicaragua. They winter as far south as northern Colombia and northwestern Venezuela.
Orchard orioles migrate over southern Florida in large numbers, and have (very rarely) been recorded wintering there as well as southern Louisiana.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
- Jaramillo, A., P. Burke. 1999. New World Blackbirds: The Icterids. Princeton: Princeton University Press.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Breeding
Regularity: Regularly occurring
Type of Residency: Breeding
Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: southeastern Saskatchewan, southern Great Lakes region, and southern New England south to central Mexico, southern Texas, Gulf Coast, and central Florida, west to Colorado and southeastern New Mexico. NON-BREEDING: central Mexico to northern and western Colombia and northwestern Venezuela (small numbers in South America).
Orchard orioles are the smallest of the North American orioles, averaging 15 to 18 cm in length, with males marginally larger than females. They have a short, squared-off tail and small, slender bill. The legs and feet are blue-gray and the eyes are dark brown for both sexes (Jaramillo and Burke 1999).
Breeding adult males are black on the head, neck, upper breast, nape, back, and scapulars. The rump, upper-tail coverts, and underparts from breast to under-tail coverts are rich chestnut. The wings are primarily black, except for chestnut epaulets and white wing bar and tips. The tail is black with narrow brownish-white tips (Jaramillo and Burke 1999).
Non-breeding adult males look much like breeding males, but olive or pale chestnut-tipped feathers may obscure the black coloration on the upperparts. The feathers on the rump and upper tail-coverts as well as the underparts from the breast to the undertail-coverts may have yellowish tips. Brownish white or gray tips on the tail may be more noticeable than on the breeding male (Jaramillo and Burke 1999).
Second year males are similar to adult females, but have a solid black bib and black between the eye and bill. The degree to which black adult plumage appears in this stage varies considerably between individuals, with some males of this age having more black feathering than others (Scharf and Kren 1996). Despite their lack of adult coloration, these males are sexually mature. Though they can breed, they are often unsuccessful in finding a mate because females generally select males with adult plumage (reviewed in Enstrom, 1993).
Hatch year males are similar to adult breeding females, but with more greenish, yellowish, or brownish upperparts and brighter yellow underparts (Scharf and Kren 1996). Flecked black feathering on the throat and between the eye and bill is possible (Jaramillo and Burke 1999).
Juvenile Orchard Orioles of both sexes are similar in appearance to adult females, but they are browner above and more yellow below (Scharf and Kren 1996). The wings are pale brown with dull white edges and two buff-white wing bars (Scharf and Kren 1996). The tail is yellowish olive green (Scharf and Kren 1996). The bill is tinged pink or orange at the base, fading with age to adult black and blue-gray (Jaramillo and Burke 1999).
Breeding adult females look much like non-breeding adult females, but have brighter underparts, a more mottled appearance on the upperparts, and a yellow sheen on the underside of the tail. Non-breeding adult females are brownish olive from forehead to uppertail-coverts on upperparts. This coloring is brighter on the forehead, more yellow on the rump and uppertail-coverts, and fades to olive on the flanks (Scharf and Kren 1996). The back is dark olive and the wings are dark gray with two white wing bars and white edging (Jaramillo and Burke 1999, Scharf and Kren 1996). The tail is olive above and yellowish underneath (Jaramillo and Burke 1999).
Second year and hatch year females are similar to adult non-breeding females. The second year females are browner on the underparts and more uniformly brown (less mottled) on the upperparts than adult females (Scharf and Kren 1996). The hatch year females are browner above and brighter yellow below than adults (Scharf and Kren 1996). The transition between these two plumage patterns is slight, and may not be noticeable in the field (Jaramillo and Burke 1999).
Range mass: 16 to 25 g.
Range length: 15 to 18 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently; male more colorful
- Enstrom, D. 1993. Female choice for age-specific plumage in the Orchard Oriole: implications for delayed plumage maturation. Animal Behavior, 45: 435-442.
Length: 18 cm
Weight: 20 grams
Habitat and Ecology
Orchard orioles exhibit a preference for settling near a source of water, such as a lake or river, and may be found in narrow riparian zones, floodplains, or marshes (Jaramillo and Burke, 1999). They are rather adaptable to local ecosystems. In the summer nesting season, for instance, they are found in mesquite brushland in Texas, orchards in Pennsylvania, and phragmite marshes in Louisiana (Scharf and Kren 1996). During migrations, they often inhabit forest edges where flowering trees and fruits are available (Scharf and Kren 1996). While overwintering in their southern ranges, they are found in the same types of habitats: light woods in Colombia, plantations in Honduras, and tropical forests in Mexico (Scharf and Kren 1996). Overall they tend to avoid dense forest, preferring more open woods or edge habitats, and are not usually found in the dry inland scrub regions of Mexico (Scharf and Kren 1996).
Orchard orioles are not particularly sensitive to human activity, and are found in suburbs, parks, and agricultural lands throughout their geographic range (Scharf and Kren 1996).
Range elevation: 1300 (high) m.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: forest
Aquatic Biomes: lakes and ponds; rivers and streams
Other Habitat Features: suburban ; agricultural ; riparian
- Scharf, W., J. Kren. 1996. Orchard Oriole. Birds of North America, 255: 1-23.
Comments: Farms, suburbs, shade trees along roads, orchards, open woodlands, scattered trees in cultivated areas, riparian woods in prairie regions; also scrub, second growth, brushy hillsides (AOU 1983). Nest usually suspended at end of branch of tree or shrub, concealed among leaves, commonly 3-6 m above ground.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Arrives in the southern U.S. in March-April; moves up Mississippi Valley (where more numerous than in Atlantic states), reaches the northern U.S. in early May (Bent 1958). Migrates through Costa Rica late July or early August through October and March-April (Stiles and Skutch 1989). Present, but uncommon to rare, in Colombia early August-early May (Hilty and Brown 1986), mostly September-March (Ridgely and Tudor 1989).
During the breeding season (late April or early May to mid July), orchard orioles are mostly insectivorous, but also consume small, ripe fruits and berries, nectar, and small seeds (Thomas 1946, Dennis 1948, Bent 1965). Stomach content data from Maryland suggests that their diet consists of about 91% insects and 9% plant material during this season (Bent 1965).
During their fall migration to southern wintering ranges (arriving as early as the beginning of July in Mexico) their diet incorporates more ripe fruits and berries such as mulberries and chokecherries, as well as nectar from roadside flowering trees and hedges in Mexico (Howell and Webb 1995).
In winter ranges (early or mid July to January), they consume the nectar of tropical flowering trees and vines such as Erythrina fusca, fruits such as mistletoe Arceuthobium), and insects obtained from foliage (Scharf and Kren 1996).
During spring migration, an abundance of blooming plants makes nectar a significant food source along with insects (Scharf and Kren 1996). Orchard orioles passing through Florida consume blooming black locust (Robinia pseudoacacia) nectar in large numbers (Bent 1965), and those in California have been observed frequently feeding at hummingbird feeders (Small 1994).
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: fruit; nectar; flowers
Primary Diet: omnivore
- Howell, S., S. Webb. 1995. A guide to the birds of Mexico and northern Central America. New York: Oxford Univ. Press.
- Small, A. 1994. California birds: their status and distribution. Vista, CA: Ibis Publ. Co.
- Thomas, R. 1946. An Orchard Oriole colony in Arkansas. Bird Banding, 17: 161-167.
Comments: Eats mainly insects obtained in trees and shrubs, also eats spiders and fruits (Terres 1980). Nonbreeding: sometimes congregates to sip nectar from trees, vines, or banana plants; takes much fruit as well as insects gleaned from foliage (Stiles and Skutch 1989); especially attracted to Erythrina trees in South America (Ridgely and Tudor 1989).
Flowering Plants Visited by Icterus spurius in Illinois
(this is the Orchard Oriole; this bird perforates [prf] the flowers of Trumpet Creeper near the base to steal the nectar [sn@prf]; this observation is from Bertin)
Bignoniaceae: Campsis radicans prf sn@prf np (Brt)
Orchard orioles are omnivorous, consuming insects and spiders, fruits, nuts, and nectar. They may help stabilize insect populations through predation in their communities. Fruits consumed by orchard orioles pass quickly through the bird’s digestive system. The seeds contained by the fruit remain undigested, spreading the seeds to other areas through its defecation.
Though they consume nectar, they are not always pollinators of the species they feed on (Scharf and Kren 1996). For some species, such as the flowering trumpet creeper (Campsis radicans), the bird pierces the flower at the base to obtain the nectar, avoiding the stamens of the flower and not pollinating the plant (Bent 1965). For other species, such as Erythrina fusca, orchard orioles do serve as a main pollinator (Morton 1979).
Like many other bird species, orchard orioles are hosts for several types of parasites, including blood parasites and various mites (Scharf and Kren 1996). Nest parasitism by bronzed cowbirds (Molothrus aeneus) and brown-headed cowbirds (Molothrus ater) is fairly common, with parasitism rates being recorded as high as 28% (Jaramillo and Burke 1999).
Ecosystem Impact: disperses seeds; pollinates
- Morton, E. 1979. Effective pollination of Erythrina fusca by the Orchard Oriole (Icterus spurius):coevolved behavioral manipulation. Ann. Mo. Bot. Gard., 66: 482-489.
Common grackles (Quiscalus quiscula) in western Nebraska expel young chicks from orchard oriole nests and break unhatched eggs (Scharf and Kren 1996). Nest parasitism by bronzed cowbirds (Molothrus aeneus) and brown-headed cowbirds (Molothrus ater) is fairly common, with parasitism rates being recorded as high as 28% (Jaramillo and Burke 1999). In California, greater roadrunners (Geococcyx californianus) have been observed preying on orchard orioles (Binford 1971).
- Binford, L. 1971. Roadrunner captures Orchard Oriole in California. California Birds, 2: 139.
NON-BREEDING: roosts gregariously, sometimes with northern oriole (Stiles and Skutch 1989), or solitary (Ehrlich et al. 1992).
Life History and Behavior
Communication and Perception
Females and young orchard orioles communicate vocally through short monotonal whistles (Scharf and Kren 1996). These vocalizations are especially common during mid-July to mid-August, after adult males leave the nesting grounds and before the females and young begin their fall migration (Scharf and Kren 1996).
Adult (including second-year) males sing upon reaching the breeding grounds, most likely in order to attract a mate, but perhaps to a limited degree to establish foraging and nesting areas (Scharf and Kren 1996). This song, a high-pitched series of notes that may include harsh interjections and downward slurs, is similar to that of Baltimore orioles (Icterus galbula) (Scharf and Kren 1996). A soft chuck and chatter may also be used (Scharf and Kren 1996).
Alarm calls comprised of chucks and chatters are used by orchard orioles to warn others of potential danger (Scharf and Kren 1996). Orchard orioles respond to these warning calls from their own species as well as similar calls from other species, such as Baltimore orioles (Icterus galbula) or Bullock’s orioles (Icterus bullockii) (Clawson 1980, Scharf and Kren 1996). Orchard orioles also use visual signals to attract mates (see Reproduction).
Communication Channels: visual ; acoustic
Perception Channels: ultraviolet
The oldest orchard oriole recorded was recaptured in the wild at 9 years and 7 months old (Scharf and Kren 1996).
Status: wild: 9 (high) years.
Status: wild: 131 months.
Lifespan, longevity, and ageing
Both second year and full adult males arrive in breeding ranges at the same time in mid May. Females arrive either with the males or, in the most northerly parts of their range, soon after (Jaramillo and Burke 1999). Both females and males use courtship displays to attract mates, including “bowing” (the head is lowered) “seesawing” (the head and tail are bobbed alternately), and “begging” (the wings are fluttered and a high trill is sung). The male also uses a flight display, during which he seesaws while flying (Scharf and Kren 1996).
Mating System: monogamous
After pair formation and copulation, females begin building a hanging cup-shaped nest (Scharf and Kren 1996). Orchard orioles generally prefer to build their nests in the fork of small branches in trees without a dense canopy, such as willows, elms, magnolia, and pecan (Scharf and Kren 1996). The nests are also commonly built in Spanish moss, and have more rarely been found in phragmites grasses (Dennis 1948). The nest takes the female about six days to complete and is woven from long strands of grass lined with animal hair, yarn, thin grass, feathers, or other available soft materials (though it may not be lined at all) (Scharf and Kren 1996).
About seven days after the female begins building the nest, she lays between two and seven eggs, depending on geographic area (Clawson 1980). The eggs are light blue, with irregular purple or brown markings mostly on the larger end of the egg (Jaramillo and Burke 1999).
The female incubates the eggs for 12-14 days, during which the male feeds her and may guard the nest (Johnsgard 1979, Foss 1994, Scharf and Kren 1996). Once the eggs hatch, the downy gray or buff-colored chicks are fed by both parents and fledge after 11-14 days in the nest (Scharf and Kren 1996).
The fledglings remain in densely covered habitat close to the nest until the family unit disbands after about a week (Sealy 1980). Adult females and fledglings of both sexes stay in the area and feed mainly on fruits in late July and early August when the males have begun their fall migration (Scharf and Kren 1996).
Orchard orioles are generally considered single-brooders, raising only one brood of offspring per season. When unseasonably harsh weather or other catastrophes destroy eggs early enough in the season, they may re-lay, raising one successful brood later in the breeding season (Scharf and Kren 1996). However, in 2004 three pairs of orchard orioles in Maryland were observed raising two successful broods in one season (Omland and Ligi, unpublished data). The second brood was laid as soon as a week to as late as a month after the young from the first brood had fledged (Omland and Ligi, unpublished data). Further research may help clarify the question of how prevalent this behavior is in orchard oriole populations.
Breeding interval: Orchard orioles typically breed once yearly.
Breeding season: Breeding occurs from May through August.
Range eggs per season: 2 to 7.
Average eggs per season: 4.
Range time to hatching: 12 to 14 days.
Range fledging age: 11 to 14 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Average eggs per season: 4.
Both male and female orchard orioles play a role in parental care. Females build the nest and incubate the eggs. During incubation, males feed the female and protect the nest. When the chicks hatch, the male and female share the responsibilities of feeding the young and carrying away feces (Scharf and Kren 1996). After the young have fledged, the male and female remain to forage with the fledglings for about a week, after which the male begins the fall migration (Sealy 1980). When males leave, females and young may stay behind and feed in large flocks (Jaramillo and Burke 1999).
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female)
- Jaramillo, A., P. Burke. 1999. New World Blackbirds: The Icterids. Princeton: Princeton University Press.
- Scharf, W., J. Kren. 1996. Orchard Oriole. Birds of North America, 255: 1-23.
- Dennis, J. 1948. Observations on the Orchard Oriole in the lower Mississippi Delta. Bird Banding, 19: 12-21.
- Foss, C. 1994. Atlas of breeding birds in New Hampshire. Arcadia: Audubon Society of New Hampshire.
- Johnsgard, P. 1979. Birds of the great plains: breeding species and their distribution. Lincoln: Univ. of Nebraska Press.
- Sealy, S. 1980. Breeding biology of Orchard Orioles in a new population in Manitoba. Can. Field-Nat, 94: 154-158.
- Clawson, S. 1980. Comparative ecology of the Northern Oriole (Icterus galbula) and the Orchard Oriole (Icterus spurius) in Western Nebraska. Master's Thesis, University of Nebraska: Lincoln.
Clutch size: 3-7 (usually 4-5). Incubation: 12-15 days, by female. Young are tended by both parents, leave nest at 11-14 days. Sometimes nests in loose colonies (114 nests on 3 ha in Louisiana).
Molecular Biology and Genetics
Barcode data: Icterus spurius
There are 2 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Icterus spurius
Public Records: 2
Specimens with Barcodes: 8
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2008Least Concern
- 2004Least Concern
Because of population declines since 1982, the American Birds Blue List considers orchard orioles a species of special concern (Scharf and Kren 1996). Overall, the eastern population is steady, but the central population has declined in recent years (Scharf and Kren 1996).
The main cause of population decline is thought to be loss or degradation of habitat. Destruction of riparian zones and other preferred areas might account for some of the population’s decline in the central range (Scharf and Kren, 1996). Pesticide spraying in orchards is another potential issue and has displaced birds in Texas and Pennsylvania (Oberholser, 1974; Scharf and Kren, 1996).
Orchard orioles are protected by the Migratory Bird Treaty Act of 1918, which prohibits hunting, trading, and disturbing the nests or eggs of orchard orioles (USFWS, 2002).
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
- 2002. "USFWS Division of Migratory Bird Management" (On-line). Birds protected by the Migratory Bird Treaty Act. Accessed April 19, 2005 at http://migratorybirds.fws.gov/intrnltr/mbta/mbtandx.html#alpha1.
National NatureServe Conservation Status
Rounded National Status Rank: N4B - Apparently Secure
Rounded National Status Rank: N5B - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Comments: A common host for the brown-headed cowbird.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
Orchard orioles may cause some minor crop damage when nesting on plantations. They may consume small amounts of stamens from fruit trees, small cultivated berries and fruits (strawberries, raspberries, cherries), figs, and grapes (Bent 1965)
Negative Impacts: crop pest
Economic Importance for Humans: Positive
Orchard orioles prey upon the cotton boll weevil (Anthonomus grandis), a major crop pest for cotton farmers (Oberholser 1974). They are also predators of many other important agricultural pest species, including caterpillars, plant lice, beetles, and worms, making them quite beneficial to farmers (Bent 1965).
Positive Impacts: controls pest population
- Oberholser, H. 1974. The bird life of Texas Vol. 1. Austin: Univ. of Texas Press.
The Orchard Oriole (Icterus spurius) is the smallest North American species of icterid blackbird. The subspecies of the Caribbean coast of Mexico, I. s. fuertesi, is sometimes considered a separate species, the Ochre Oriole.
This species is 6.3 inches (16 cm) long and weighs 20 g. The bill is pointed and black with some blue-gray at the base of the lower mandible (Howell and Webb 1995). The adult male of the nominate subspecies has chestnut on the underparts, shoulder, and rump, with the rest of the plumage black. In the subspecies I. s. fuertesi, the chestnut is replaced with ochre (Howell and Webb 1995). The adult female and the juvenile of both subspecies have olive-green on the upper parts and yellowish on the breast and belly. All adults have pointed bills and white wing bars. (Orchard Orioles are considered to be adults after their second year.) One-year-old males are yellow-greenish with a black bib.
Habitat and range
The breeding habitat is semi-open areas with deciduous trees. I. s. spurius breeds in spring across eastern North America from near the United States-Canada border south to central Mexico. A 2009 study also found breeding in the thorn forest of Baja California Sur and the coast of Sinaloa during the summer "monsoon"; this region had previously been thought to be only a migratory stopover (Rohwer, Hobson, and Rohwer, 2009). I. s. fuertesi breeds from southern Tamaulipas to Veracruz (Howell and Webb 1995). These birds enjoy living in shaded trees within parks along lakes and streams. The nest is a tightly woven pouch attached to a fork on a horizontal branch. Their nests tend to sit close together.
The nominate subspecies' winter range extends from the coastal lowlands of central Sinaloa and southern Veracruz south to northern Colombia and northwestern Venezuela (Scharf and Kren 1996). The ochre subspecies has been observed in winter on the Pacific slope of Mexico (Howell and Webb 1995).
Nominate Orchard Orioles depart from their winter habitats in March and April and arrive in their breeding habitats from late April to late May. Usually, they leave their breeding territories in late July and early August and arrive on their winter territories in mid August. These birds are nocturnal migrants.
While in breeding season, they eat insects and spiders. When the season changes, their diet also includes ripe fruit, which quickly passes through their digestive tract. During the winter, their diet consists of fruit, nectar, insects and seeds.
When in flight, Orchard Orioles generally swoop close to the ground and fly at or below treetop level
During courtship, females display themselves in 3 unique ways. The first way is bowing their head and torso toward the male. Seesawing, the second courtship display, involves repetitively alternating lowering and raising the head and tail. The third display is begging, which is fast-paced fluttering of wings halfway extended, followed by a high whistle.
- Foster, Mercedes S. (2007): The potential of fruiting trees to enhance converted habitats for migrating birds in southern Mexico. Bird Conservation International 17(1): 45-61. doi:10.1017/S0959270906000554 PDF full text
- Hilty, Steven L. (2003): Birds of Venezuela. Christopher Helm, London. ISBN 0-7136-6418-5
- Rohwer, Sievert, Hobson, Keith A., & Rohwer, Vanya (2009): Migratory double breeding in Neotropical migrant birds. Proceedings of the National Academy of Sciences on line. doi:10.1073/pnas.0908121106 Abstract, PDF full text (subscription required)
- Scharf, William C. & Kren, Josef (1996). Orchard Oriole (Icterus spurius), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: full text (subscription required)
- Stiles, F. Gary & Skutch, Alexander Frank (1989): A guide to the birds of Costa Rica. Comistock, Ithaca. ISBN 0-8014-9600-4