Fly by night: Indigo buntings know something about that phrase.
These 5-inch, sparrow-sized birds migrate during the night using star patterns for navigation. They have internal clocks that enable them to continually adjust their angle of orientation to certain stars even as the stars move through the sky. Wow, the miracle of migration.
Indigo buntings return to Minnesota in mid-May from their winter bases in Mexico, Central America and northern South America.
Female indigo buntings are light brown with faint markings. Males are vibrant blue even though their feathers lack blue pigment and are actually black. Their dazzling blue comes from microscopic structures in the feathers that refract and reflect blue light, much like the airborne particles that cause the sky to appear blue. The male's showy plumage can be a handicap, as these iridescent blue birds are prized as caged birds in parts of Mexico. They have been trapped for illegal sale.
Male indigo buntings sing with cheerful gusto. We hear their whistled, bubbling songs through late spring into summer. The birds nest in fields, rural roadside thickets, along streams, and where woodlands meet open areas. They are a boon to farmers, consuming insect pests and weed seeds.
Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.
