Bobolinks and Meadowlarks

Male Bobolinks singing

The songs of these birds are some of the most iconic sounds of summer hayfields.

■ Male Bobolinks display by singing in flight, and females apparently prefer males with longer flight songs. Exercise such as flying generally requires steady breathing, but singing involves complex breath control. And the song of the Bobolink is extreme: it can be over ten seconds long with more than one hundred phrases. If we try to run and sing at the same time, we end up gasping for air, so how do birds balance these two activities? For one thing, their lungs are much more efficient than ours (see this page). When we fill our lungs with air, the oxygen is rapidly absorbed. We can exhale to sing, but we won’t get more oxygen until we inhale fresh air. A bird can store fresh air in its air sacs, and as that air is exhaled to produce song it also delivers fresh oxygen to the lungs. Singing in flight is still a remarkable feat, but getting enough oxygen could be one of the smaller issues.

■ Birds and farming have always had a complicated relationship. Farmers blame birds for damaging crops, but also appreciate the insect control that birds offer—birds consume more than 500 million tons of insects a year worldwide. Small family farms have provided lots of high-quality bird habitat in hedgerows, weedy edges, pastures, and other sites. As recently as the early 1900s much of the eastern United States was farmed, and species like the Eastern Meadowlark and Bobolink thrived, nesting on the ground in the open meadows and hayfields that were a part of every farm. With the decline of farming in many areas, and a more industrialized style of farming, most of this habitat is now gone. Even where hayfields still exist they are essentially traps: hay is cut multiple times in a season, and there is not enough time between cutting for birds to complete a nesting cycle.

■ Meadowlarks are unusual in having their sharpest vision oriented slightly above the horizon. Since they spend most of their time on the ground in the open, this may be an adaptation for looking up for danger. Their vision is also oriented forward so they can see the tip of their bill—most birds can’t—but this creates a larger blind spot behind the head, which means they have to turn their head more to scan their surroundings. One of their foraging techniques is to stick their closed bill into matted grass and force the bill open. As the bill opens, the eyes automatically turn slightly forward and down. This gives them a view right between the open mandibles into the gap in the grass, so they can see and grab any potential food.