Indigo Bunting

The bright blue Indigo Bunting is most frequently seen along forest edges, here including habitats such as power line cuts, rows of trees between fields, and regenerating forest stands. Unlike many other species that use such habitats they seem to prefer trees over shrubs and are thus less common in the earliest stages of succession. Perhaps this variation in habitat use explains why they are not showing the consistent population declines seen in species like Eastern Towhee. While buntings show gradual declines in the southeastern United States, here in the northeast their populations appear highly variable but averaging out to relatively stable.

There have been extensive studies of song development in the Indigo Bunting. The typical song is a series of paired notes or phrases, often rendered as “fire fire where where here here” and variations thereof. Like all songbirds they need to learn their songs when young by listening to other males, In the case of the Indigo Bunting however, they learn from neighboring males rather than from their father. When they return to breed their first year, they switch songs to match those of nearby males, resulting in “neighborhoods” where all the buntings sing a similar set of songs. As birds come and go from these clusters the dominant songs continue to change.

In late summer Indigo Buntings congregate in weedy and grassy areas, including corn fields, where they often join sparrows to feed on abundant seeds. Adult males start losing their blue body feathers in August, sometimes while they are still singing on territory, and by winter the only blue that remains is in their wing and tail feathers. During this time the young males look like females but with scattered blue feathers. As a result, these pre-migration flock can contain a wide range of plumages, from all blue males to dull brown females, with some of the latter revealing themselves to be males when they flash blue in flight. The blue in Indigo Buntings is not a pigment but caused by light refracting through microscopic structures in the feathers, so if you see a bunting in the shade it will appear brown or black.