Baltimore Oriole Nesting (Behavior, Eggs + Location)

Last updated: 23 January 2023

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Baltimore Oriole Nesting (Behavior, Eggs + Location)

The Baltimore oriole (Icterus galbula), named after the yellow-orange and black colors of Baltimore heraldry, is an icterid blackbird common throughout North America. The male Baltimore oriole is strikingly colored and tough to miss among its deciduous forest habitats.

Here, we’ll investigate Baltimore oriole nesting, including habitat, nest appearance, construction, and more.

Baltimore oriole nests are exceptional, consisting of a suspended pendulum-like sac about the size of a baseball. The nest is typically precariously attached to a drooping branch of a deciduous tree. While the nest looks exposed to bad weather, it’s strong and is well out of the way of predators.

The female builds the nest, and the process requires determination, patience, and craft. First, she weaves strong fibers together like strips of bark, flexible twigs, string, and milkweed silk, which are attached to the branch and strengthened by coiling the materials together.

The rim is constructed first, and the female will then hang upside down and build the cup.

Baltimore oriole nests are some of the most remarkable of any North American bird - read on to learn more about them!

Baltimore oriole nests are exceptional, consisting of a suspended pendulum-like sac about the size of a baseball

Baltimore oriole nests are exceptional, consisting of a suspended pendulum-like sac about the size of a baseball

Nest Location

Where do Baltimore Orioles nest?

Baltimore orioles live east of the Rocky Mountains in both Canada and the USA. They typically nest in deciduous trees and tall mature shrubs within open woodland or forest fringes. They usually avoid deep forests.

Nests are built on the narrow shafts of long, drooping branches.

Do Baltimore Orioles nest in the same place every year?

Baltimore orioles typically do not nest in the same place every year, though they do return to the same breeding territories.

Others claim they might return to the same tree each year - especially if they raised a successful brood there. Nests are sometimes recycled for material, but seldom re-used.

Do Baltimore Orioles nest in backyards?

Baltimore Orioles typically nest in the upper branches of deciduous trees in wooded areas. They rarely nest in backyards unless the backyard contains suitably mature deciduous trees.

Close up of a nesting Baltimore Oriole

Close up of a nesting Baltimore Oriole

Do Baltimore Orioles use nest boxes?

Baltimore Orioles construct incredible pendulum-like nests that are not suitable for nest boxes. Instead, they prefer to make their nests out of grass, leaves, and twigs in deciduous trees and, rarely, tall shrubs.

What trees do Baltimore Orioles nest in?

Baltimore Orioles typically nest in the outer branches of deciduous trees, such as oaks, maples, elms, and sycamores, and fruit trees, such as apple and cherry. They choose slim drooping branches to attach their nest to in what looks like a very precarious structure!

How high are Baltimore Oriole nests?

Baltimore Oriole nests are usually built between 10 to 30 feet above the ground, but some have been recorded as high as 90 ft.

This means that nests are tough to spot with the naked eye as they’re usually well-hidden in mature trees.

Baltimore Oriole nest suspended from a tree during the early spring

Baltimore Oriole nest suspended from a tree during the early spring

Nest Appearance

What do Baltimore Oriole nests look like?

Baltimore Oriole nests are cup-shaped hanging or pendulum structures made of grasses, string, and other plant fibers, lined with softer materials like hair and feathers.

They are usually suspended from dropping branches or hanging from shrub branches. The nests are usually about the size of a baseball and look like a hanging pouch or sock.

They’re certainly one of the more striking nests of any North American bird and look incredibly precarious hanging among drooping deciduous branches.

However, their strength belies their appearance, as some Baltimore oriole nests have been recorded for more than one year. In fact, 85% of nests in one study lasted for over a year.

How big are Baltimore Oriole nests?

Baltimore oriole nests are pretty small. They measure around 4 to 6 inches wide, and 4 to 8 inches deep and have a 2 - 3 inch wide opening. They’re compact and cozy inside.

Inside of a Baltimore Orioles nest

Inside of a Baltimore Orioles nest

Phenology

What time of year do Baltimore Orioles nest?

Baltimore Orioles stick to the traditional spring breeding season, which spans late April through July. Nesting peaks in May, especially further north, as it’s colder. Nesting is earlier in the south, where it’s milder in early spring. Nest construction is delayed if the weather is poor.

How long do Baltimore Orioles nest for?

Baltimore orioles nest for two to three months at the most. During this time, the male claims a territory, and the female will get to work constructing the complex nest, which takes up to three weeks to complete.

Eggs are laid and incubated for around 12 to 14 days, and the chicks fledge after a couple of weeks. With no interruptions, the entire process takes just longer than a month. In reality, nest building may be delayed by adverse weather, or the nest could fail.

If the nest fails early in the season, pairs don’t re-attempt - the nest is simply too arduous to build - so they only get one shot per season!

Female Baltimore Oriole outside of her nest

Female Baltimore Oriole outside of her nest

What month do Baltimore Orioles lay eggs?

In most regions, egg-laying peaks in May. It’s usually slightly later in the north and earlier in the south. In any case, egg laying might be postponed due to adverse weather, as this makes it tough for the female to build the nest.

Where do Baltimore Orioles nest in the winter?

Baltimore orioles migrate in the winter and usually head to the Gulf Coast, Antilles, and Central America as far south as Panama and isolated parts of extreme northern South America.

Female Baltimore Oriole gathering nesting materials

Female Baltimore Oriole gathering nesting materials

Nest Construction

How do Baltimore Orioles build their nests?

Baltimore Orioles build their nests in the fork of a deciduous tree, typically high up in the tree on a drooping branch. The female is the master builder and does the vast majority of the work, while the male sometimes delivers material.

First, the female oriole gathers materials like strips of plant material like grasses, twigs, thin strips of bark, thin fibers, and cotton-like materials like hair or wool.

Fibers are initially tied to branches and are gradually woven together in twirls and coils - some nests are thought to involve around 10,000 individual ‘stitches’. The nest is usually made in two halves or from top to bottom. The separate parts are then stitched together.

The resulting pendulum-like nest is sturdy despite seemingly floating in the air without a platform or support. In addition, the female seems to ‘stress test’ the nest at intervals to ensure its strength.

In one study, 85% of nests lasted at least a year, a testament to the female’s immense abilities. Nests take 40 hours to build, or two to three weeks.

Female Baltimore Oriole weaving to make her nest

Female Baltimore Oriole weaving to make her nest

What do Baltimore Orioles use for nesting?

Nests are created from various materials, including grapevine bark, milkweed silk, wool, strips of park, soft twigs, horsehair, and artificial fibers such as string, cellophane, twine, and fishing line. The complete nest is lined with feathers, wool, and other soft fibers.

Do male or female Baltimore Orioles build the nest?

The female Baltimore oriole builds the nest while the male occasionally supplies material. The female definitely masterminds the intricate process.

Female (left) and male (right) Baltimore Oriole breeding pair building the nest together

Female (left) and male (right) Baltimore Oriole breeding pair building the nest together

Baltimore Oriole Eggs

What do Baltimore Oriole eggs look like?

Baltimore oriole eggs are blue-gray with brown-to-black markings concentrated at the larger end of the egg. Some markings are blotchy, whereas others are web-like.

How many eggs do Baltimore Orioles lay?

Female Baltimore orioles nearly always lay 4 to 5 eggs, rarely 3 to 6.

Do male Baltimore Orioles sit on eggs?

The female Baltimore oriole incubates while the male takes close attention, often lingering near the nest. He sometimes feeds the female and chases away parasitic Cowbirds and other intruders.

Baltimore Oriole chick peeking out the top of the nest

Baltimore Oriole chick peeking out the top of the nest

Fledgling and Parental Care

When do baby Baltimore Orioles leave the nest?

Baby Baltimore orioles fledge after 12 to 14 days. Both the male and female intensively feed the young during this time.

How many broods do Baltimore Orioles have?

Baltimore orioles have just one brood. If that brood fails, they’ll not re-attempt, as the nesting process is simply too complex and long-winded.

Who feeds Baltimore oriole chicks?

Both the male and female contribute evenly to feeding chicks. Chicks are generally fed regurgitated insects.

Close up of a recently fledged Baltimore Oriole chick

Close up of a recently fledged Baltimore Oriole chick

FAQs

Do Baltimore Orioles abandon their nests?

In the early breeding season, Baltimore orioles usually wait for bad weather to subside before the female begins nest construction.

Once constructed, the nest is almost invulnerable to land predators but is still vulnerable to other birds, like Cowbirds, who lay their eggs inside the oriole’s nest. Cowbirds generally find it difficult to lay their eggs inside the oriole’s pouch, however.

They won’t abandon the nest unless it irretrievably fails.

Do Baltimore Orioles nest on the ground?

Baltimore orioles nest high up in the branches of a deciduous tree, often at a height of 30 ft at least.

Where do Baltimore Orioles nest at night?

The female sleeps in the nest during incubation. Otherwise, they sleep in treetop roosts.

How to attract nesting Baltimore Orioles?

Baltimore orioles are sometimes attracted by blossoms and fruit trees, like oranges. Provide them with fresh water, mealworms, and fruits. Milkweed silk and cotton may help them build their nests.

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