Photo: © Shutterstock.com/Paul Reeves Photography. The longevity record for wild Baltimore orioles is 11 years, in captivity they have been kept for more than 14 years
Bright, tuneful and with an elegant mating display, the Baltimore oriole has lots going for it, says Bill Naylor
THE Baltimore oriole (Icterus galbula) is one of nine American orioles in the family Icteridae, sometimes called the American blackbirds or American troupials. They are unrelated to the golden oriole (Oriolus oriolus) and the other 28 species of true orioles in the genus Oriolus.
Apart from a few species, icterids are sadly virtually unknown to European aviculture. They vary greatly in plumage and form, and are intelligent with strong vocals; many of the species are fine songsters. But the American colonists seemed to have chosen the common names for this family out of a hat. It includes grackles, which are unrelated too; mynas; blackbirds, which are not thrushes; meadow larks, which are not larks; and the parasitic cowbirds, which have no obvious connection to ruminants.
Although there has been a ban on the export of native North American birds for a long time, a number of American orioles – including the Baltimore – migrate to South America where, for many years, there was no ban on exporting birds. Consequently, at least six of the nine species of American orioles were infrequently exported from the Americas and kept by birdkeepers in Europe. The Baltimore, Bullock’s (I. bullockii), dark-throated (O. xanthonotus) and spot-breasted
(I. pectoralis) being the most commonly imported. In the summer months, American orioles breed in various parts of North America; some Baltimore orioles as far north as Canada. They then migrate south as far as South America, where they spend the winter months before returning in the spring.
The Baltimore oriole is named after the gold and black family coat of arms of Lord Baltimore, a popular politician who first colonised the state of Maryland. Apart from Audubon’s (I. graduacauda) and Scott’s oriole (I. parisorum), which are yellow, the male Baltimore oriole possesses the orange and black plumage common to most oriole species. The plumage of the Baltimore oriole is a deep fiery orange and its entire head is jet black. The female, like most female orioles, is more sombre coloured with no jet-black coloration. Some female Baltimore orioles have a black throat and can be confused with immature orchard orioles (I. spurius).
Apart from the South American troupials (also incterids), the only North American species the Baltimore oriole can be confused with is the closely related Bullock’s. Where their ranges coincide they hybridise and in these locations hybrids that display features of both species are common. For a while, both species were considered to be a single species. But after hybridisation was found to be restricted, the two reverted to being classed as separate species.
American orioles are extrovert and very much similar to corvids and starlings in personality and behaviour. Once they are acclimatised in temperate climates they become hardy, although they do not tolerate sub-zero temperatures.
Like starlings, they are omnivorous. They have a liking for nectar and sweet fruit, and sometimes cause damage to grape crops. Grapes or cherries are left on the vine and the fruit is pierced to extract juice and some pulp. In certain areas, they have become habituated to stealing nectar from hummingbird feeders. So much so, that bird-feeder manufacturers have designed an oriole feeder that can be loaded with soft fruits (newly imported Baltimore orioles were often given fortified nectar to supply nutrients). Being intelligent birds, they are opportunistic and will investigate most food sources. Occasionally, they use their feet to hold down food items. They are very assertive and their aviary companions have to be chosen with care, because they can bully and are not to be trusted with smaller birds. Although they have been kept in non-breeding groups for short periods, when breeding they are aggressively territorial. A pair to an aviary should be the rule.
Being birds of the high canopy, they are strong fliers and require a spacious aviary, as high as possible, ideally furnished with plants. A floor covering of bark and leaves will enable these inquisitive birds to forage and investigate. They are also enthusiastic bathers and an appropriate-sized pond will be much appreciated. In outdoor aviaries, similar to parakeets and pigeons, they will hang upside down from the aviary wire to enjoy rain and mist sprays. Captive Baltimore orioles thrive on a diet of fruit, insects, softfood and softbill pellets. They have a liking for soaked raisins, oranges, grapes and nectar, and soft-bodied insects such as caterpillars and locusts. In the wild, they have been observed killing and eating hummingbirds.
Throughout the year, American orioles are solitary. Ringing records show they return to the same location to breed and sometimes the same tree. As trees burst into leaf, males arrive first from the winter locations with females shortly after. Courtship starts almost immediately, with the male Baltimore displaying (preferably in bright sunlight) the orange plumage of his breast and then his rump. He lifts himself up, puffing his breast out and then bows in front of the female while spreading his tail and partly opening his wings. At the same time, he emits a low whistling song. If the hen is receptive, she cowers chattering and fluttering her wings.
The breeding territory usually only occupies the nesting tree. The nest site is high and often hidden; usually about 9-12m (30-40ft) in the canopy, and difficult to find. Here, suspended on the end of a thin branch, the female builds a woven pendulous nest. The unusual shape is the derivation of the American oriole’s alternative name “hangnest”.
The male brings nest material (sometimes material from old nests is used), but the female does the majority of the work. The base of the nest is woven from sturdy plant fibres, smaller fibres and string if the female can locate any. These are woven in a purse-shaped nest, which is usually lined with fine grass and horse hair. In warmer southern states, the nest lining is less dense. In captivity, a wide variety of nest material including raffia and short pieces of string (not nylon string) should be provided. The entrance hole is at the top of the nest rather than the side. Construction of the nest can take from three days to a week.
Three to four greyish-white eggs, blotched with black and brown, especially at the larger end, are incubated by the female for 12-14 days. They are single brooded, but they will lay again if unable to rear youngsters. The young are fed on a variety of insects, mainly caterpillars, beetles, etc, obtained from tree foliage.
For the first few days, the young are fed by regurgitation. They are reasonably silent until they fledge at about two weeks and then start to emit a mournful call earning them the nickname “cry baby”. This sometimes attracts predators such as squirrels and jays.
When the chicks leave the nest they resemble the females, minus the dark feathering on the head, and undergo a partial moult. The adults have a partial moult following breeding and later go through a complete moult revealing winter plumage.
Bill Naylor has worked in zoos, bird gardens and museums around the world.
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