The bright orange and black Baltimore Oriole (Icterus galbula) was named in reference to the colors of the coat of arms of the 17th century Lord Baltimore. These orioles are widespread in North America east of the Great Plains during the northern summer and winter mainly from Mexico south to northern Colombia, northern Venezuela, and Trinidad, although small numbers may winter in the southeastern United States and Greater Antilles.

As a result of frequent hybridization between the Bullock's (I. bullockii) and Baltimore Orioles where their ranges meet in the Great Plains, these two orioles were at one time treated as conspecific (i.e., members of the same species), representing two forms of a species that was known as the Northern Oriole. However, genetic studies have indicated that these two species are not even each other’s closest relatives (for a full discussion of this issue, see Jacobsen and Omland 2011).

Baltimore Orioles breed in deciduous and mixed woodlands, usually in open woods or along edges rather than in the interior of dense forests. They may be common in towns and other relatively developed areas with appropriate trees (especially elms). The familiar nest of the Baltimore Oriole is a hanging pouch woven of plant fibers and may be seen in shade trees in towns and suburbs. The nest is typically attached firmly by its rim near the end of a slender drooping branch 6 to 9 (sometimes 2 to 18 or more) meters above the ground. There are 4 to 5 eggs (range 3 to 6) eggs. Eggs are incubated by the female for around 12 to 14 days. Nestlings are fed by both parents and leave the nest around 12 to 14 days after hatching.The diet include mainly insects in summer, especially caterpillars, including hairy types avoided by many other birds. They also consume many berries and sometimes cultivated fruit. They may feed on nectar from some flowers and will take sugar water at feeders. The liquid, musical tones of the Baltimore Oriole's song floating down from the treetops are a familiar harbinger of spring in the eastern United States.

(Kaufman 1996; AOU 1998)

Baltimore orioles are neotropical migrants. They spend summers in the Nearctic, primarily the eastern United States. They breed from Wisconsin to Maine and south to central Mississippi and Alabama, northern Georgia, and western South Carolina and North Carolina. They winter in the neotropics as far north as Mexico and sometimes the southern coast of the United States.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

Global Range: Breeding range extends from central Alberta, central Saskatchewan, southern Manitoba, western Ontario, northern Michigan, southern Ontario, southwestern Quebec, central Maine, southern New Brunswick, and central Nova Scotia south to eastern Texas, central regions of Gulf coast states except Florida (accidental), north-central Georgia, western South Carolina, central North Carolina, central Virginia, Maryland, and Delaware, and west to the western edge of the Great Plains (AOU 1998). Range during the northern winter extends from Nayarit and Veracruz (casually from coastal California and Sonora) south through Middle America to northern Colombia, northern Venezuela, and Trinidad, regularly in small numbers in the Atlantic states north to Virginia, in the Greater Antilles east to the Virgin Islands, and casually elsewhere in eastern North America (AOU 1998). This species migrates regularly through the southeastern and south-central United States and northeastern Mexico, and in coastal California, rarely through the northern Bahama Islands and Yucatan Peninsula, and casually elsewhere in western North America (AOU 1998).

Adult birds are 17 to 20 cm long, somewhat smaller than a robin. There is sexual dimorphism in plumage and in size; males are 1-5% larger than females in a variety of measurements. Adult males have a black head, bill, and back, and a bright orange breast, rump, and underparts. Their wings are black with orange and white wing bars, and the tail is orange with black streaks. Adult females are paler than males, olive-brown to orange. Their wings are brown with white wing bars, and the bill is gray. She may have traces of black on her head. Immature animals are variable, but typically resemble the female. Males take over a year to reach adult plumage.

Range mass: 28 to 42 g.

Range length: 17 to 20 cm.

Range wingspan: 9 to 10 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful

Average basal metabolic rate: 0.5052 W.

Length: 22 cm

Weight: 34 grams

Systems

• Terrestrial

Baltimore orioles prefer open woods, with a strong preference for deciduous over coniferous trees. They are very adaptable, however, and can be found breeding in a variety of habitats. They are rare on farmlands but have adapted well to urban parks and suburban landscapes. In Mexico, they winter in flowering canopy trees over shade coffee plantations.

Habitat Regions: temperate ; tropical ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; rainforest ; scrub forest

Other Habitat Features: urban ; suburban ; agricultural ; riparian

Comments: Habitat includes open woodland, deciduous forest edge, riparian woodland, partly open situations with scattered trees, orchards, and groves of shade trees. In migration and winter this oriole also occurs in humid forest edge, second growth, and scrub; treetop level in coffee and cacao plantations, and savanna groves. Nests are placed in trees, an average of around 25-30 feet (8-9 meters) above ground, usually at the end of a drooping branch.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some 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.

Most Baltimore orioles migrate north through the southeastern United States in March-April, arrive in the northern states and Canada in April-May; males precede females by a few days. Southward migration begins in late July or early August and continues in the United States through August and September and sometimes later. South-bound migrants arrives in Costa Rica early September, depart by early May (Stiles and Skutch 1989). The species is present in South America mostly October-April (Ridgely and Tudor 1989).

Most individuals from eastern North America probably cross Gulf of Mexico en route to winter range (Rohwer and Manning 1990).

Baltimore orioles eat primarily caterpillars, including many pest species. They also eat other insects, some small fruits, and nectar. They are an important predator of the nuisance forest tent caterpillar, Malacosoma disstria, which it eats in both its larval and pupal forms. Large larvae are seized and smashed against a twig to break them open and avoid the setae (stiff, hair-like structures). Pupae are pulled out of their cocoon.

In suburban and rural areas, I. glabula can be attracted to feeders by providing orange halves, grape jelly, or artificial nectar. Adults who come to feeders will take their young to the feeder once they are fledged.

Baltimore orioles eat primarily caterpillars, including many pest species. They also eat other insects, some small fruits, and nectar. They are an important predator of the nuisance forest tent caterpillar, which it eats in both its larval and pupal forms. Large larvae are seized and smashed against a twig to break them open and avoid the setae (stiff, hair-like structures). Pupae are pulled out of their cocoon.

In suburban and rural areas, Baltimore orioles can be attracted to feeders by providing orange halves, grape jelly, or artificial nectar. Adults who come to feeders will take their young to the feeder once they are fledged.

Animal Foods: insects; terrestrial non-insect arthropods; mollusks

Plant Foods: fruit; nectar

Primary Diet: carnivore (Insectivore )

Comments: Gleans insects, especially caterpillars, from trees and shrubs; also eats various fruits (Terres 1980) and nectar (Stiles and Skutch 1989). South America: often feeds in flowering trees (Ridgely and Tudor 1989).

Baltimore orioles are important predators on insects in the communities in which they live. Because they live in forested areas and prey on caterpillars, the lifestage at which many insects do most damage to plants, they are especially important in protecting forest trees from damage.

Baltimore orioles have many different kinds of predators, including larger birds and mammals. Most predators take eggs, nestlings, or fledglings. In western Massachusetts, avain predators caused 16% of egg losses and 9% of nestling and fledgling losses. In response to predators, both males and females give alarm calls, and chase and mob (harass) predators.

Known Predators:

• common grackles (Quiscalus quiscula)
• American crows (Corvus brachyrhynchos)
• eastern screech owls (Otus asio)
• blue jays (Cyanocitta cristata)
• black-billed magpies (Pica pica)
• red squirrels (Tamiasciurus hudsonicus)
• fox squirrels (Sciurus niger)
• eastern gray squirrels (Sciurus carolinensis)
• domestic cats (Felis silvestris)

Icterus galbula Linnaeus: Icteridae, Passeriformes
(this is the Baltimore Oriole; this bird perforates [prf] the flowers of Trumpet Creeper to steal the nectar [sn@prf]; this observation is from Bertin)

Bignoniaceae: Campsis radicans prf sn@prf np (Brt)

Icterus galbula (Baltimore oriole, chickadee, least flycatcher, rosebreasted grosbeak, willow thrush) is prey of:
Accipiter striatus
Accipiter cooperii
Bubo virginianus

Based on studies in:
Canada: Manitoba (Forest)

This list may not be complete but is based on published studies.

Icterus galbula (Baltimore oriole, chickadee, least flycatcher, rosebreasted grosbeak, willow thrush) preys on:
Araneae
Insecta

Based on studies in:
Canada: Manitoba (Forest)

This list may not be complete but is based on published studies.

Nonbreeding: usually in groups of 2-5 (rarely 15), in definite home ranges; sometimes large communal roosts (Stiles and Skutch 1989).

The male sings all summer. His song is rich and flute-like, with each individual having a distinct song. The female song is generally shorter and simpler. The call, from both sexes, is a whistled "hew-li." Nestlings beg loudly.

Baltimore orioles also use postures and movements to communicate, such as male courtship displays, female wing-flutter displays, and nestling wing-flutters when begging for food.

Communication Channels: visual ; acoustic

The oldest recorded Baltimore oriole in the wild lived to 11 years and 7 months old. They have been recorded living 14 years in captivity.

Range lifespan

Status: wild: 11.5 (high) years.

Range lifespan

Status: captivity: 14 (high) years.

Average lifespan

Status: wild: 139 months.

Maximum longevity: 14 years

Baltimore orioles are generally considered monogamous, although evidence suggests that extra-pair copulation is reasonably common. In the spring, males display to females on their territory by singing and/or chattering while hopping from perch to perch in front of her. Males give a bow display, bowing with wings lowered and tail fanned. Some females ignore these displays while others sing and give calls or a wing-quiver display in response. The wing-quiver display involves leaning forward, often with tail partly fanned, and fluttering or quivering slightly lowered wings.

Mating System: monogamous ; polygynandrous (promiscuous)

Males arrive on breeding grounds in the spring a few days before females. Courtship displays by the male consist of bowing, to show off the bright orange front and black back, and singing. The female builds a woven pouch nest hanging from the end branches of trees, well concealed by leaves. She builds a new nest each year with little or no help from the male. Icterus galbula prefers to build in elms, maples, willow, or apples, twenty-five to thirty feet above the ground. Any available plant and animal fibers may be used.

The female lays four to six eggs, typically four. The eggs are pale grayish or bluish white, irregularly blotched and streaked with browns and black. The female incubates for twelve to fourteen days. Both parents feed the nestlings. Fledglings will stay with their parents for two weeks, and are fed by their parents duing that period. Baltimore orioles lay only one brood per season.

Breeding interval: Baltimore orioles breed once yearly.

Breeding season: Breeding occurs from May to June.

Range eggs per season: 3 to 7.

Average eggs per season: 4.

Range time to hatching: 11 to 14 days.

Average time to hatching: 12 days.

Average time to independence: 2 weeks.

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.

The female alone broods nestlings; the male occasionally feeds the brooding female, but she usually forages for herself. Parents feed nestlings by regurgitation during the first few days of the nesting period.

Parental Investment: no parental involvement; altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

In most areas, nesting begins in May (or late April in southern locations). Clutch size is 3-6 (commonly 4-5). Incubation, by the female, lats 12-14 days. Young are tended by both parents, leave nest at 12-14 days, generally in June oe early July. Yearling males (in their second calendar year) resemble adult females but nevertheless may successfully attract a mate and raise young. This species ejects brown-headed cowbird eggs from the nest (Sealy and Neudorf 1995, Condor 97:369-375).

The following is a representative barcode sequence, the centroid of all available sequences for this species. 

 
There are 11 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.
 

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 11
Species: 11
Species With Barcodes: 1

Baltimore orioles are protected by the Migratory Bird Treaty Act. They may be at risk due to habitat loss, as they prefer wooded areas, but this is not well documented. Although direct human impacts on oriole populations are unknown, the increase in number of orioles wintering in temperate North America may be due to an increase in bird feeders in backyards and elsewhere.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B - Secure

United States

Rounded National Status Rank: N5B - Secure

Rounded Global Status Rank: G5 - Secure

Baltimore orioles may occasionally damage crops of peas or small fruits.

Negative Impacts: crop pest

Baltimore orioles are attractive songbirds that will come to feeders. They are generally liked by both serious birdwatchers and casual backyard enthusiasts for both their appearance and song. They are also important predators on some insect pests such as forest tent caterpillars.

Positive Impacts: ecotourism ; controls pest population

Comments: Sometimes a pest of citrus crops in the winter range (Stiles and Skutch 1989).

Comments: Formerly considered conspecific with I. BULLOCKII under the name 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.