The Indigo bunting is one of North America’s most-loved songbirds. The male Indigo bunting is a beautiful indigo-blue color and is tough to miss as it sings throughout the day across much of the eastern USA.
Indigo buntings breed in the USA and winter in Central America and the northern coast of South America, but where do they nest?
Indigo buntings return from migration in late winter to early spring and begin courtship in April. Once paired, they start building the nest, and females lay the first brood in early May. Nests are constructed in low-lying vegetation at the height of around 1m or less.
Most nests are built in fields, at the roadside, near footpaths, and in hedges and shrubs. The female does all the work, using small supporting forks in shrubs and foliage to support a small open-cupped nest that measures less than 10 cm across.
There is so much more to learn about the nesting behaviors of this charming bird - read on to find out!
Female Indigo Bunting feeding chicks inside of the nest
Most Indigo Bunting nests are built in wild or semi-wild locations near the edges of paths, railways, roadsides, fields, and open areas neighboring forests and woodlands. While Indigo buntings nest in shrubs and bushes near or in backyards, they don’t nest in bird boxes.
Indigo buntings breed across North America north of Mexico, including some parts of southern Canada. They’re common across the Great Plains, west to Colorado, south to Arizona, New Mexico, Texas, and Florida. They’re most abundant in Arkansas, Illinois, Missouri, Indiana, Kentucky, and Tennessee.
There’s no substantial evidence that Indigo buntings nest in the same place each year, but they may return to the same breeding grounds each year after migration.
If the backyard contains dense low-lying shrubs, then Indigo buntings could certainly take up residence there in the breeding season. However, they don’t use bird boxes.
Close up of an Indigo Bunting nest with newly hatched chicks inside
Indigo buntings don’t use nesting boxes. Instead, they build small dome-shaped nests in shrubs and bushes at a height of 1m or lower.
Nests are typically built in low-lying dense shrubs and vegetation. Some 40 plant species have been recorded as nesting sites; raspberries, dogwood, goldenrod, poison ivy, stinging nettles, rose, juniper, and various species of herbs are all popular choices.
Nests are infrequently built in the lower story of a tree or young tree saplings. Chosen species require enough vertical stability to support the nests, but other than that, these flexible birds make use of whatever shrubs are available.
A small percentage of nests are built in trees at a height of 10m or above (around 1% in one study).
Indigo bunting nests are built at a height of just 1m or less. They prefer to nest in bushes, hedges, and shrubs rather than trees, but some nests are constructed in young tree saplings.
On rare occasions, Indigo buntings choose to build nests in the lower story of a tree at the height of around 10m or so at the most, but studies suggest this consists of less than 1% of nests.
Nesting male and female Indigo Buntings
Indigo bunting nests are open cups built from leaves, grasses, bark, and stems. The base of the nest is built from leaves which act as a platform. Then, other materials are woven around the stems and forks of the supporting shrubs.
Materials are woven into a cup with looser threads and spider web acting as binding. The cup is lined with softer materials like grasses, rootlets, and soft leaves. The resulting cup is firmly attached to the supporting vertical stems of the bush, shrub, or hedge.
Indigo bunting nests are small, measuring around 10cm in diameter and 10cm deep. Earlier nests are usually bigger, presumably as it’s colder, and they require extra insulation. This also means that they take longer to build, around 8 to 10 days in some cases.
The nest of an Indigo Bunting, with two eggs and one Cowbird egg inside
Indigo buntings nest in May through until as late as August and September. However, studies in Michigan and Ontario found that first eggs are typically laid in mid-May.
Many pairs raise two broods; second clutches may be laid in late August or even September - one nest contained young on 26th September!
Indigo buntings have a relatively long breeding season that lasts from late April and early to mid-May until August or even September. Indigo buntings often raise two broods to three broods, which partly accounts for their long breeding season.
Most female Indigo buntings lay eggs in mid-May. However, pairs will re-attempt if the first nest(s) fails until around August or even September.
Many pairs raise two broods also, in which case they lay eggs through July and August or even September. The very latest young fledge in September - though they’re unlikely to survive unless the weather is particularly mild.
The female handles all nest construction duties. The male might attend the construction process but doesn’t actually do any work. It’s a pretty arduous process that takes around 7 to 8 days to complete in most cases.
Female Indigo Buntings build the nests without any help from the males
The female Indigo bunting collects material and assembles the nest on her own. The male attends but doesn’t help. It’s a pretty arduous process which usually takes around 6 to 8 days.
Nests in warm weather are quicker to build, presumably as the nest doesn’t need to be so thick and insulated. The nest is woven around the vertical stems of a low-lying bush or shrub.
Indigo bunting nests are built with a base of leaves, particularly aspen. Materials are woven together with fine plant threads and spider webs. The nest cup is lined with various types of grass, thistledown, bark and animal hair.
The female builds the nest without any assistance from the male. The male attends and watches, but doesn’t help.
Male Indigo Buntings can often be found watching the nest building process, but don't help with the build
Indigo bunting eggs are tiny, measuring around 20mm x 18mm. They weigh just 2 grams. They’re wholly white, although a small percentage (<1%) are marked with reddish-brown blotches.
The average clutch is 3 to 4 eggs, though eggs have been found with as many as six eggs.
The male takes no part in nest building or incubation, nor does he feed the chicks until they’re old enough to fly.
Three unhatched white Indigo Bunting eggs inside of the nest
Young Indigo buntings fledge after 9 to 12 days, but this might be accelerated to 8 days if the nest is disturbed. The young might remain in the nest for around 14 days in cold weather with no disturbances.
Indigo buntings typically have two broods, though three have also been recorded. The male feeds the fledged young while the female prepares for the next brood - which is just about the only part he plays in raising the chicks!
Many Indigo bunting nests fail to predation (88% of all nest failures in one study). Predators include opossums, red foxes, wildcats, corvids - especially Blue jays, the Eastern racer and raccoons.
Nests are parasitized by cowbirds - the cowbird lays eggs in the Indigo bunting’s nest so the female bunting incubates the cowbird egg in addition to its own. This vastly increases the risk of nest failure.
Female Indigo Bunting returning to feed hungry chicks inside the nest
Indigo buntings only abandon their nests if they have no choice, for example, if it’s destroyed by predators or adverse weather. However, they’re reluctant to approach the nest if humans are nearby, so nests built near humans risk failure if this impacts the feeding of the chicks.
An exception is when the female Indigo bunting spots a cowbird in the vicinity. Cowbirds regularly parasitize Indigo bunting nests and lead to high nest failure rates.
Indigo buntings don’t nest on the ground but do nest very near the ground at the height of just 1m or so.
Indigo buntings roost in the trees. If the female is incubating the chicks, she’ll sometimes remain in the nest all night.
Indigo buntings visit back garden bird feeders, where they’ll feed on various seeds and mealworms. They may nest in backyards, provided there are substantial bushes or shrubs.
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