the baltimore oriole (icterus galbula) is a small icterid blackbird common in eastern north america as a migratory breeding bird .
it received its name from the resemblance of the male's colors to those on the coat-of-arms of lord baltimore .
like all new world orioles , it is named after an unrelated , physically similar family found in the old world: the oriolidae .
observations of interbreeding between the baltimore oriole and the western bullock's oriole , icterus bullockii , led to both being classified as a single species , called the northern oriole , from 1973-1995. research by james rising , a professor of zoology at the university of toronto , and others showed that the two birds actually did not interbreed significantly .
the baltimore oriole is the state bird of maryland .
it is also the inspiration for the baltimore orioles baseball club .
this medium-sized passerine measures 1722 cm (6.78.7 in) in length and spans 2332 cm (9.112.6 in) across the wings .
their build is typical of icterids , as they have a sturdy body , a longish tail , fairly long legs and a thick , pointed bill .
the body weight averages 33.8 g (1.19 oz), with a range of weights from 22.3 to 42 g (0.79 to 1.48 oz) .
the male oriole is slightly larger than the female , although the size dimorphism is minimal by icterid standards .
adults always have white bars on the wings .
the adult male is orange on the underparts shoulder patch and rump , with some birds appearing a very deep flaming orange and others appearing yellowish-orange .
all of the rest of the male's plumage is black .
the adult female is yellow-brown on the upper parts with darker wings , and dull orange-yellow on the breast and belly .
the juvenile oriole is similar-looking to the female , with males taking until the fall of their second year to reach adult plumage .
baltimore orioles are found in the nearctic in summer , primarily the eastern united states .
they breed from minnesota to maine and south to central mississippi and alabama and northern georgia .
they migrate to winter in the neotropics as far north as mexico and sometimes the southern coast of the united states , but predominantly in central america and northern south america .
some areas of the southern united states may retain orioles all winter if they have feeders that appeal to them .
the range of this bird overlaps with that of the similar bullock's oriole in the midwest , and the two species were once considered to be conspecific under the name northern oriole because they form fertile hybrids .
the baltimore oriole is a rare vagrant to western europe .
baltimore orioles are often found high up in large , leafy deciduous trees , but do not generally reside in deep forests .
the species has been found in summer and migration in open woodland , forest edge , and partially wooded wetlands or stands of trees along rivers .
they are very adaptable and can breed in a variety of secondary habitats .
in recent times , they are often found in orchards , farmland , urban parks and suburban landscapes as long as they retain woodlots .
in mexico , they winter in flowering canopy trees , often over shade coffee plantations .
baltimore orioles are basically solitary outside their mating season .
the species is generally considered monogamous , although evidence suggests that extra-pair copulation is reasonably common .
in the spring , males establish a territory then display to females by singing and chattering while hopping from perch to perch in front of them .
males also give a bow display , bowing with wings lowered and tail fanned .
depending on their receptiveness , the females may ignore these displays or 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 .
the baltimore oriole's nest is built by the female .
it is a tightly woven pouch located on the end of a branch , consisting of any plant or animal materials available , hanging down on the underside .
trees such as elms , cottonwoods , maples , willows or apples are regularly selected , with the nest usually located around 7 to 9 m (23 to 30 ft) above the ground .
the female lays three to seven eggs , with the norm being around four .
the eggs are pale gray to bluish white , measuring 2.3 cm  1.6 cm (0.91 in  0.63 in) on average .
the incubation period is 12 to 14 days .
once the nestlings hatch , they are fed by regurgitation by both parents and brooded by the female for two weeks .
after this the young start to fledge , becoming largely independent shortly thereafter .
if the eggs , young , or nest are destroyed , the oriole is unable to lay a replacement clutch .
predation is a common source of mortality , typically also occurring with eggs , nestlings and fledgings .
common predators at baltimore oriole nests can include common grackles , american crows , blue jays , black-billed magpies , tree squirrels and domestic cats , which most commonly capture newly fledged orioles or adults engaged in brooding behavior .
rapacious birds commonly prey on both young and fully-grown orioles , the most prolific being the eastern screech owl and cooper's and sharp-shinned hawks .
somewhat larger rapacious birds also sometimes opportunistically predate the oriole , including peregrine falcons , great horned owls , and barn owls , while merlins may do so while orioles are migrating .
the record lifespan for a wild bird was 11 years and 7 months , with captive orioles living up to 14 years .
baltimore orioles forage in trees and shrubs , also making short flights to catch insects .
they acrobatically clamber , hover and hang among foliage as they comb high branches .
they mainly eat insects , berries and nectar , and are often seen sipping at hummingbird feeders .
their favored prey is perhaps the forest tent caterpillar moth , which they typically eat in their larval stage , and can be a nuisance species if not naturally regulated by predation .
the larvae caterpillar are beaten against a branch until their protective hairs are skinned off before being eaten .
unlike american robins and many other fruit-eating birds , baltimore orioles seem to prefer only ripe , dark-colored fruit .
orioles seek out the darkest mulberries , the reddest cherries , and the deepest-purple grapes , and will ignore green grapes and yellow cherries even if they are ripe .
baltimore orioles sometimes use their bills in an unusual way , called "gaping": they stab the closed bill into soft fruits , then open their mouths to cut a juicy swath from which they drink with their tongues .
during spring and fall , nectar , fruit and other sugary foods are readily converted into fat , which supplies energy for migration .
many people now attract baltimore orioles to their backyards with oriole feeders .
such feeders contain essentially the same food as hummingbird feeders , but are designed for orioles , and are orange instead of red and have larger perches .
baltimore orioles are also fond of halved oranges , grape jelly and , in their winter quarters , the red arils of gumbo-limbo (bursera simaruba) .
if they discover a well-kept feeder , orioles lead their young there .
