Indigo Bunting
Most birds nest in early spring or, at the latest, early summer, but there are a handful of small birds that wait to reproduce until late summer. The American Goldfinch is a good example of a bird that waits until late summer when their main food source, small plant seeds, are more plentiful. They utilize the excess seeds to feed their young growing chicks.
But right now, in late summer, there is one small bird that is very actively reproducing: the Indigo Bunting (Passerina cyanea). The Indigo Bunting is a small, seed- and insect-eating bird in the cardinal family, Cardinalidae. It is highly migratory and is one of the last birds to arrive in spring and stays through late summer before heading back south for the winter.
As their name implies, the male Indigo Bunting is a brilliant blue color from head to tail, sometimes appearing cobalt, sometimes turquoise, sometimes almost black depending on the light. The surprising truth is that the bird has no blue pigment in its feathers. Like the blue of the sky, the color is produced by microscopic structures, deep within each feather barbule that bend and scatter light. Viewed in poor light on a cloudy or rainy day, the same blue bird looks gray and rather plain.
Females are a completely different story. They are warm brown, modestly streaked, and easy to overlook. This difference makes sense in the bird world. A male benefits from being visible as he sings and defends a territory. A female benefits from being hidden, especially when she is sitting on eggs or tending young in a nest tucked low in dense vegetation. In many ways, the quiet brown female is the reason the species succeeds, even if the blue male gets most of the attention.
Indigo Buntings favor forest edges. They are a bird of brushy fields, overgrown pastures, woodland borders, powerline cuts, roadside thickets, and abandoned farms where shrubs are reclaiming the ground. This is why they often show up where habitat is in transition. A manicured lawn will not do much for them. A messy corner with native grasses, blackberry canes, dogwood, sumac, goldenrod, and young trees is definitely more inviting.
During late summer, when these birds are reproducing, insects and spiders are important foods, especially for growing nestlings. Caterpillars, beetles, grasshoppers, and aphids are all on the menu. At other times, Indigo Buntings feed heavily on small seeds and even berries. This is another reminder that what we call weeds are often great food for wildlife. Remove every wild stem from a property, and you remove a portion of the local food web.
The nest is usually built by the female, placed low in a shrub or a tangle of branches, often only a few feet above the ground. It is a small cup of woven grasses, leaves, stems, and bark strips, secured with spider silk and lined with finer plant materials. A typical nest contains three or four pale blue eggs. Incubation lasts roughly two weeks, and the young leave the nest less than two weeks after hatching.
I find that at this time of year, the song is one of the best ways to find them. Males commonly sing a series of paired phrases, delivered again and again from an exposed perch. Birders sometimes describe the cadence as double notes: sweet-sweet, chew-chew, here-here. Young males learn their songs from other males and their fathers, creating local song neighborhoods.
Perhaps the most astonishing part of the Indigo Bunting’s life happens in early fall when they migrate. These tiny birds migrate at night from the breeding grounds across much of the eastern and central United States and southern Canada to wintering grounds in Mexico, Central America, the Caribbean, and northern South America. Several research studies on Indigo Buntings have shown that they use the stars to help guide their journey. Imagine a bird weighing about half an ounce lifting into the night and navigating by peering into the night sky.
For all their beauty, Indigo Buntings face familiar life challenges. Loss of brushy habitat, intensive mowing, expanding housing development, collisions with vehicles, and nighttime collisions with buildings or towers during migration all take a toll. Fortunately, they are still widespread and considered a species of low conservation concern, but common birds deserve our attention before they become uncommon.
If you want to help, leave some edges of your yard a little wild. Plant native shrubs. Reduce mowing where possible. Let a patch of goldenrods stand through the season. Keep cats indoors. Turn off unnecessary lights during migration. Small choices, repeated across many yards and farms, create the kind of living landscape these birds need.
When you are out enjoying the warmth of the late summer days, listen to the song or watch for a flash of blue along a fence row. It is the marvelous Indigo Bunting, a half-ounce traveler that knows the stars. Until next time…
About Stan
Stan Tekiela is an author, naturalist, and wildlife photographer who travels extensively to study and photograph wildlife. He can be followed on Instagram, Facebook, and YouTube, and contacted via his website at naturesmart.com.