On their breeding grounds in eastern and east-central North America, you’ll most often find Baltimore Orioles high in leafy deciduous trees, but not in deep forests; they prefer open woodland, forest edge, river banks, and small groves of trees. They also forage for insects and fruits in brush and shrubbery. Baltimore Orioles have adapted well to human settlement and often feed and nest in parks, orchards, and backyards. On their winter range in Central America, Baltimore Orioles occupy open woodlands, gardens, and shade-grown coffee and cacao plantations. They frequently visit flowering trees and vines in search of fruit and nectar.Back to top
Baltimore Orioles eat insects, fruit, and nectar. The proportion of each food varies by season: in summer, while breeding and feeding their young, much of the diet consists of insects, which are rich in the proteins needed for growth. In spring and fall, nectar and ripe fruits compose more of the diet; these sugary foods are readily converted into fat, which supplies energy for migration. Baltimore Orioles eat a wide variety of insects, including beetles, crickets, grasshoppers, moths, and flies, as well as spiders, snails, and other small invertebrates. They eat many pest species, including tent caterpillars, gypsy moth caterpillars, fall webworms, spiny elm caterpillars, and the larvae within plant galls. However, orioles can also damage fruit crops, including raspberries, mulberries, cherries, oranges and bananas, and some fruit growers consider these birds a pest. Back to top
The female chooses a nest site within the territory defended by her mate. She anchors the nest firmly to a fork in the slender upper branches of a tree. Baltimore Orioles often nest in American elms, but will build in other trees, especially maples and cottonwoods. The distinctive nest usually hangs below a branch, but is sometimes anchored along a vertical tree trunk.
Baltimore Orioles build remarkable, sock-like hanging nests, woven together from slender fibers. The female weaves the nest, usually 3 to 4 inches deep, with a small opening, 2 to 3 inches wide, on top and a bulging bottom chamber, 3 to 4 inches across, where her eggs will rest. She anchors her nest high in a tree, first hanging long fibers over a small branch, then poking and darting her bill in and out to tangle the hank. While no knots are deliberately tied, soon the random poking has made knots and tangles, and the female brings more fibers to extend, close, and finally line the nest. Construction materials can include grass, strips of grapevine bark, wool, and horsehair, as well as artificial fibers such as cellophane, twine, or fishing line. Females often recycle fibers from an old nest to build a new one. Males occasionally bring nesting material, but don’t help with the weaving. Building the nest takes about a week, but windy or rainy weather may push this as long as 15 days. The nest is built in three stages: first, the female weaves an outer bowl of flexible fibers to provide support. Next, springy fibers are woven into an inner bowl, which maintains the bag-like shape of the nest. Finally, she adds a soft lining of downy fibers and feathers to cushion the eggs and young.
|Clutch Size:||3-7 eggs|
|Number of Broods:||1 brood|
|Egg Length:||0.8-1.0 in (2.1-2.5 cm)|
|Egg Width:||0.6-0.7 in (1.5-1.7 cm)|
|Incubation Period:||11-14 days|
|Nestling Period:||11-14 days|
|Egg Description:||Pale grayish or bluish white blotched with brown, black, or lavender.|
|Condition at Hatching:||Helpless, eyes closed, with sparse white down.|
Baltimore Orioles are agile feeders that comb the high branches of trees in search of insects, flowers and fruit. They are acrobatic foragers, clambering across twigs, hanging upside down, and fluttering to extend their reach. They also fly out from perches to snatch insects out of the air. Because they forage in the treetops, they are more often seen than heard, but males often sing from conspicuous posts at the tops of trees, where their blazing orange breast attracts the eye. Both males and females may be glimpsed fluttering among the leaves, and come readily to bird feeders supplied with fruit or nectar. Many other birds defend large feeding territories, but orioles defend only the space near their nests, and so you may see several neighboring orioles feeding close to each other. When courting, the male displays by hopping around the female, bowing forward and spreading his wings to reveal his orange back. A receptive female responds by fanning her tail, lowering and fluttering her wings, and making a chattering call.Back to top
Baltimore Oriole populations have been declining throughout their range by an estimated 0.84% per year for a cumulative decline of 36% between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 12 million. They rate a 10 out of 20 on the Continental Concern Score, indicating a species of relatively low conservation concern. Because they breed in North America and winter in Central and South America, Baltimore Orioles are vulnerable to deforestation and habitat loss in many different countries and their conservation requires international cooperation. Spraying insecticides onto trees not only kills off Baltimore Orioles’ insect prey but may poison the birds directly. In addition, Orioles and many other songbirds migrate at night, when they can become disoriented by lights or rainstorms and crash into tall structures such as skyscrapers and radio towers.Back to top
Ehrlich, P. R., D. S. Dobkin, and D. Wheye (1988). The Birder's Handbook. A Field Guide to the Natural History of North American Birds, Including All Species That Regularly Breed North of Mexico. Simon and Schuster Inc., New York, NY, USA.
Lee, C., and A. Birch (1998). Field identification of female and immature Bullock's and Baltimore orioles. Birding 30:282-295.
Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
Rising, James D. and Nancy J. Flood. (1998). Baltimore Oriole (Icterus galbula), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.
Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.