Indigo Buntings breed in brushy and weedy areas. They're common on the edges of woods and fields; along roads, streams, rivers, and powerline cuts; in logged forest plots, brushy canyons, and abandoned fields where shrubby growth is returning. While migrating and in winter, Indigo Buntings forage in fields, lawns, grasslands, rice fields, as well as in shrubs, and trees. Back to top
Indigo Buntings eat small seeds, berries, buds, and insects. Common seed forage includes thistles, dandelions, goldenrods, and grain such as oats; berries eaten include blueberries, strawberries, blackberries, serviceberries, and elderberries. Spiders and insect prey, which form the majority of their diet during summer months, may include caterpillars, grasshoppers, aphids, cicadas and beetles such as canker worms, click beetles, and weevils. The brown-tail moth caterpillar, which is covered with noxious hairs that cause nasty rashes and respiratory problems in people, presents no obstacle to a hungry bunting. On arrival to breeding grounds in spring, Indigo Buntings may feed on twigs, buds, and leaves of trees including aspen, cottonwood, oaks, beech, elm, maple, and hickory.Back to top
Indigo Buntings nest in fields and on the edges of woods, roadsides, and railroad rights-of-way. The female chooses a concealed nest site in low vegetation, within a meter of the ground. She locates the nest in a crotch or fork where branches meet, amid a supporting network of vertical and diagonal twigs. Occasionally an Indigo Bunting builds her nest in crop plants like corn or soybeans.
The female Indigo Bunting builds the nest alone—a process that takes up to 8 days early in the season and as little as 2 days later in the summer. The male may watch but does not participate. The nest is an open cup woven of leaves, grasses, stems, and bark, and wrapped with spider web. The inside of the cup is lined with slender grasses, tiny roots, strips of thin bark, thistle down, and sometimes deer hair. The cup is about 1.5 inches deep inside, with an outside diameter of 3 inches and an inside diameter of two inches.
|Clutch Size:||3-4 eggs|
|Number of Broods:||1-3 broods|
|Egg Length:||0.7-0.8 in (1.7-2.1 cm)|
|Egg Width:||0.5-0.6 in (1.3-1.5 cm)|
|Incubation Period:||11-14 days|
|Nestling Period:||8-14 days|
|Egg Description:||Unmarked white; a few have brownish spots.|
|Condition at Hatching:||Naked except for sparse down; eyes closed; helpless.|
Foraging for seeds and gleaning insects off branches in low vegetation, Indigo Buntings hop along the ground and cling athletically to stems and reeds. Singing males tend to perch high in shrubs, trees, or on telephone lines. When disturbed, an Indigo Bunting may fly to the top of a shrub, raise its crest feathers, and swing its tail from side to side. Indigo Buntings usually forage alone during the breeding season; on their wintering grounds and during spring and fall migration, they feed in flocks on lawns and open grasslands. Males defending territory approach each other with slow, fluttering "butterfly" display flight, holding their wings at right angles to their bodies. Early in the breeding season, you may see two males grappling in the air and falling to the ground, singing loudly, clasping each other's feet.Back to top
Indigo Buntings are generally abundant throughout their range, though populations have declined yearly by an estimated 0.62% for a cumulative decline of about 28% between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 77 million and rates them 9 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Indigo Bunting populations decrease with intensive agriculture, reforestation, frequent mowing of roadsides and fields, and increasing urbanization; they increase with the expansion of shrubby, weedy habitat. The males' showy plumage can be a handicap, as these bright blue birds are prized as cage birds in parts of Mexico, where they have been trapped for illegal sale. Unfortunately, Indigo Buntings and many other small birds are commonly hunted on their tropical wintering grounds. During migration, many die after flying into buildings and transmission towers. These birds breed and sing along roadsides, and collisions with vehicles kill many birds in summer. In the 1970s, Indigo Buntings colonized Canada's Maritime Provinces, moving northward from their established breeding range in Maine. A warming climate may drive populations farther northward.Back to top
Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.
Emlen, S. T. (1967b). Migratory orientation in the Indigo Bunting, Passerina cyanea. Part II: Evidence for use of celestial cues. Auk 84:309-342.
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