Bird of the Month: Indigo Bunting
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
An Indigo Bunting, a common bird of the Eastern United States, made a rare visit to the west at Marymoor Park in Redmond, WA in June 2020.
The lovely all blue male Indigo Bunting has been called the Blue Canary (Dunne) for good reason. Its song is a bright and cheery combination of whistled notes, often in pairs, which can continue for hours throughout the day. This bunting loves to sing from a high and open perch. The song of the Indigo Bunting can be heard at the Macaulay Library.
Indigo Bunting
Scientific Name: Passerina cyanea
Length: 5.5”
Wingspan: 8”
Weight: 0.51 oz (14.5 g)
AOU Alpha Code: INBU
ONE OF OUR FOUR PASSERINA BUNTINGS
Along with the Indigo Bunting, the Lazuli (P. amoena), Varied (P. versicolor), and Painted (P. ciris) Buntings, comprise the four buntings in the genus Passerina, from the Latin for sparrow. The Blue Grosbeak (P. caerulea) is also in this genus, but we will focus on the four buntings. All four species display strong sexual dimorphism. The males are brightly colored in alternate (breeding) plumage and the females are more cryptically colored in brown plumage.
THE COLOR BLUE
The species epithet cyanea is from the Greek kuaneos, dark blue (Holloway). The male Indigo Bunting in summer is entirely bright blue with the color darker and almost purple on the head (Payne). The female in contrast is a pale brown with two faint wing bars and streaks on the chest and flanks. In winter, the female takes on a more cinnamon coloration following a late summer molt.
The male Indigo Bunting which was seen at Marymoor Park in June sported plumage that was a mix of blue and brown, which was the result of the molt strategy of birds in the genus Passerina (Howell). The male Indigo Bunting takes two spring cycles to molt into all blue plumage. After its first winter it will undergo its first pre-alternate molt in which feathers on its head, body, and some wing and tail feathers will be blue and other feathers will be brown. These first spring males can have a blotchy appearance and often have white feathers under the belly (Payne). The Marymoor Indigo Bunting was a bird in this stage of development. After its second winter it will molt into its definitive alternate all-blue plumage and will do so every spring after that.
FAVORS BRUSHY EDGE HABITAT
The Indigo Bunting is a bird that inhabits dense shrubs and low trees. The male will mark the territory with song and can have more than one female in the territory. The female does almost all the caring for the nest and hatchlings. The nest is an open cup of grass, weeds, and leaves lined with finer materials. Usually three to four bluish-white eggs are deposited and will hatch in less than two weeks. The female feeds the chicks and they will fledge in about 10 more days. The males will sometimes assume the feeding of the fledglings as the female attempts a second brood (Kaufman).
STATUS AND DISTRIBUTION
The Indigo Bunting is widespread from the northern Great Plains across all the eastern United States and in southern Canada south of the coniferous forests. Sine the 1940s it has expanded its range as a summer resident into parts of the southwestern United States. It has bred at Grand Canyon National Park since 1964. Indigo Buntings winter almost entirely outside the United States and migrate to Mexico, Central America, and some Caribbean Islands. However, some individuals can move to sites far outside their normal migration route and be seen in British Columbia and Washington (Payne).
The population of Indigo Buntings is healthy and in some places in the southeastern United States it may be the most common songbird along roadsides. Their numbers increase in areas of shrubs with weeds and herbs, and diminish in areas of agriculture, urbanization, and where old fields are returning to forest (Payne). There are no management plans for this abundant species.
Photo credit Alabama Rick. References available upon request from amccormick@eastsideaudubon.org.