See all posts in the Birds of Carver County series

Indigo buntings (Passerina cyanea) are another of the colorful summer birds in Carver County as we benefit from our proximity with the Minnesota River. They are part of the finch family of birds, even though their beak gives the impression of a sparrow. If you have seed feeders in your area, you could see these buntings eating alongside American goldfinches.

As you walk near woods with shrubs or fields that have natural vegetation, you also might see an indigo bunting on the end of a high blade of grass that is producing seeds and is bending over with the weight of the feeding bunting. Or during its breeding season, you could see them in trees hunting for small spiders and insects that provide them with protein. If there is a group of them, you could see a variety of blue and brown plumages. Breeding males are bright blue in sunlight and more like black if they’re tucked behind leaves. Females and fledglings are all shades of brown. Males will have some brown if they haven’t gotten to breeding age yet, which might take two years.

Another characteristic that takes time to evolve is their singing. By late summer, juveniles will be trying out their song that will later be identified by their competitors and their reaction to it will influence their “pecking order.” Territories are based on this hierarchy. In detailed behavior studies, it has been found that most juvenile males will copy the song of a successful adult to try to achieve a copy of the older bird’s status. It doesn’t actually work out to give them more success at mating, but this trait provides lots of time for scientific investigation.

From The Birds of the World website species description: “Song is comprised of a series of loud, ringing metallic chirp-notes of nearly equal stress, the notes are usually given in pairs. Song is more patterned than melodic, and it lacks trills and complex bubbles.” With five songs every minute, and singing nonstop for an hour, you have to admire their energy and intent, even if their singing isn’t up to the musical ability of your neighboring robins and orioles.

Indigo buntings are about the same size as goldfinches and warblers—five to six inches long, a wingspan of seven to eight inches and a weight of half an ounce. During their breeding season in Minnesota, their mate may be hard to identify because she will look like a plain brown sparrow. She won’t sing, and after mating, the male will not do more than stay near her as she alone builds a nest, lays eggs and takes care of the young until they fledge. Her nest will probably be built near the ground in a field or nearby shrubs that provide the cover of a canopy. 

Like other nesting birds, she has to contend with the ever-present brown-headed cowbirds. As long as she has eggs of her own, she’ll raise and feed the cowbird hatchling. This results in her offspring being reduced in size and number due to the appetite and aggression of the larger step-sibling.

Their bright sky-blue color comes from the structure of their feathers and the reflection and refraction of sunlight. This condition is the same as for our blue jays. Both species can almost disappear if they are covered by shade and sunlight cannot perform its colorful magic. Let’s all hope for sunny days, energetic songsters and the opportunity to share time with our Indigo Buntings.

For more information:

• The Sibley Guide to Birds, David Allen Sibley
• Reader’s Digest Book of North American Birds
• Birds of Minnesota and Wisconsin, Janssen, Tessen, and Kennedy
• Breeding Birds of Minnesota, Pfannmuller, Niemi and Green
• The Audubon Society’s Encyclopedia of North American Birds, John K. Terres
• Birds of the World, Cornell Lab of Ornithology
• Online: All About Birds, Cornell Lab of Ornithology LINK
• Online: Minnesota Breeding Bird Atlas