A trained observer can pick out two dozen different bird species in a June morning chorus of singers.
Birds begin singing close to 4:30 a.m. — American robins first. In the evening, the same robins sing and call until just past 9:40 p.m.
So, why do birds sing, call or make mechanical sounds? It’s their means of communicating with other birds and the world around them. The chief function of song in most species is to proclaim territory. It warns males of the same species to stay away, and attracts females. Too, the singing helps maintain and strengthen the bond between the mated pair. There are social songs, such as the canary-like one used by American goldfinches in flock formation.
Call notes are used in a variety of situations. There are calls of alarm, anger, scolding and location. As an example, the cheeps of warblers help these nocturnal migrants stay together in flight. It’s thought that a bird sings at times because it is bubbling over with the pure joy of living.
Some other things I’m observing in the wild: Waterfowl now are mostly all in a flightless condition. They are molting their flight feathers. Purple martins are busy feeding young nestlings. Late broods of wood ducks are jumping from their nest boxes or tree cavities. They hatch-out after 28 days of brooding by the female alone, spend a day in the nest getting to know each other, and jump on the 29th day. About 90 percent will go between 8 and 8:30 a.m. Sometimes the ducklings will go a bit earlier if it is hot, and once in a while as late as 10 a.m.
Wild turkeys can be seen with their small young, called poults. On these summer evenings over most of our cities and towns, watch for common nighthawks flying, calling and feeding on insects. By 9:40 p.m., nearly all chimney swifts are in their chimney roosting sites.
Although birds do not have sweat glands, they stay cooler by vaporizing moisture from their skin. However, birds are pre-eminently “panting animals” and their evaporative cooling comes mostly from the moist membranes lining the respiratory tract. On hot afternoons, it’s not unusual to see American robins, American crows or other birds perched quietly in the shade with their bills wide open. They are panting.
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. He worked as a naturalist for 50 years.