This new mini-series highlights the fascinating and marvelous ecology of grassland bird nesting, written by Madison Audubon education director Carolyn Byers. Click here for all Into the Nest posts.
Into the Nest: Grassland Basics
We all have a scene that pops into our heads when we think of ‘grassland birds’. Maybe you simply think of the birds themselves. Perhaps you see sunlight glistening on dewy prairie, while a northern harrier floats a few feet above the grass. Do you hear a dawn chorus of bobolinks and eastern meadowlarks punctuated by the quiet whisper of Henslow’s sparrow? Whatever image you conjure, I imagine it warms your heart.
Goose Pond Sanctuary is home to hundreds of acres of restored grasslands, some of the few remaining in Wisconsin. Photo by Arlene Koziol
Grassland birds can fall into two categories: obligate or generalist species. The latter are simply birds that are able to use grassland habitat for nesting, foraging, or loafing around. The former require grasslands during their breeding season, and their fates are inextricably tied to the habitat. The obligate birds that we’ll be focusing on throughout this Into the Nest series include bobolink, eastern meadowlark, grasshopper, savannah and, Henslow’s sparrow, upland sandpiper, dickcissel, and northern harrier.
This striking bobolink needs grasslands to nest. Photo by Kelly Colgan Azar
Populations of obligate grassland birds are in steep decline because grasslands themselves are a declining habitat. Less than one 10th of 1% of tallgrass prairie remains in Wisconsin—a habitat type that used to be quite common.
Historically, habitat was lost when Europeans settled the Americas. They used the fertile land to produce necessary crops, and they suppressed the fire that maintains prairie habitat. Grassland bird declines were slow in those days, since they were still able to use historic agricultural fields. Birds could nest in crops like wheat and hay, as harvest generally occurred after nesting was complete. Modern intensification of agricultural practices has made using these surrogate grassland habitats challenging for birds. Herbicides and pesticides, as well as more frequent harvests, make these fields a more hostile environment. Grassland bird populations have been sharply declining since the 1950s.
Click on the images below for a larger view. Once enlarged, hover your mouse over the images for captions.
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Our Wisconsin grassland birds are either just returning from migration, or currently traveling. Birds all have their own migration strategies and routes: different solutions to the same resource scarcity problem.
Henslow's sparrows are beginning to return to Wisconsin for the summer. Photo by Arlene Koziol
Short-distance migrants overwinter in the southern U.S. They use local environmental cues like temperature, insect activity, and plant growth to time their migration north, and are therefore generally able to adjust to weather patterns that deviate from the norm. Eastern meadowlarks are the early birds of the bunch. They move north with the melting snow, and can typically withstand a few light dustings of snow after they arrive. Grasshopper and Henslow’s sparrow wait a bit longer, and the first sightings for WI were reported on eBird on April 21.
Long-distance migrants overwinter in Central and South America. As they’re so far away, the local environmental cues that short-distance migrants respond to would do little to inform them of conditions in North America. Instead, these birds rely on photoperiod, or day length, to know when it’s time to head north. The first bobolink sighting in WI reported on eBird was from April 21 in Iowa County—there was only one lone male. It had just flow about 12,500 miles from southwestern Brazil, Paraguay, or Argentina. Upland sandpipers make a similar journey, and were also spotted in WI on April 21.
Map of migration intensity moving north, as of April 28, 2018. Map courtesy of the Wisconsin Bird Conservation Initiative.
As birds arrive back to their breeding grounds, they spend time foraging and recovering from migration. They begin to prepare for the upcoming breeding season. They delight birdwatchers everywhere!
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Dickcissels are a beautiful, migratory grassland bird that benefits from the Migratory Bird Treaty Act. Photo by Kelly Colgan Azar
This summer, to celebrate Year of the Bird and 100 years of bird conservation under the Migratory Bird Treaty Act, we’ll be posting regular articles about grassland bird nesting ecology. My M.S. thesis focused on grassland bird nesting ecology, and I’m excited to share my knowledge—and stories from the field- with you! We’ll go into the nest to learn about chick behavior, adult sleep habits, feeding and fledging. We’ll discuss predation and learn about how adult birds respond to different predators. You’ll get to see beautiful photos of nests, eggs, and chicks, as well as video footage straight from the nest! Best of all, the next time you’re out hiking in your favorite Wisconsin prairie, you’ll feel a bit closer to the birds you love.
If you’re interested in reading more and can’t wait for the next post, you can read more about my thesis work here.
Stay tuned for our next edition of Into the Nest, when I'll give you a picture into the world of setting up nesting territories, and the drama of male competition.
Written by Carolyn Byers, Madison Audubon education director
Cover photo by Carolyn Byers
