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Slipping into a patch of woods in western Dane County, Jim Berkelman ignores the swarming mosquitoes and strains to sort through the early- morning chatter of warblers, robins and vireos and the nearby drum of a pileated woodpecker. “I’m hearing something I wouldn’t expect to hear,” says Berkelman, a lecturer in the Department of Forest and Wildlife Ecology at CALS and a volunteer contributor to the Wisconsin Breeding Bird Atlas II, a comprehensive, volunteer-powered survey of birds that nest in Wisconsin.

Experienced birders use their ears as much as their eyes to identify species, and Berkelman thinks he hears a northern parula, a small warbler that doesn’t typically nest this far south. Finding a bird, Berkelman explains, is only the start. The point of the Atlas, he notes, is to identify and map where birds in Wisconsin are courting, nesting, breeding and raising their broods.

Jim Berkelman out birding on behalf of the Atlas. Photos by Wolfgang Hoffmann.
Jim Berkelman out birding on behalf of the Atlas. Photos by Wolfgang Hoffmann.

To be sure of that, “atlasers,” as volunteer observers like Berkelman are called, must find tangible evidence that a species has actually taken up residence. A nest, of course, is the most obvious clue. But most birds are assiduously covert in their nesting and only conspicuous players like robins, herons, orioles, house wrens and bluebirds construct their nests in ways that make them easy to find and identify.

Other definitive hallmarks of breeding birds include observations of birds carrying nesting material or food for nestlings; distraction displays where birds seek to draw animals, other birds or humans away from a nest; and, of course, fledglings. Some bird species are fastidious as well and carry fecal matter away from occupied nests. Such an observation is also a telltale sign of breeding and can be used by an atlaser to confirm breeding activity and provide a new data point that science can ultimately draw on.

Following a rising wooded path to the top of a hill, Berkelman’s rounds on this warm June day encompass two different types of ecosystems: forest, and open fields and prairie. His block is designated as a “priority block,” a specified block within a six-block “quad” on a grid of more than 7,000 three-mile-by-three-mile blocks that covers Wisconsin. Within that grid are 1,175 priority blocks, each of which requires at least a year’s documentation of breeding birds within a five-year period to ensure that the state is uniformly surveyed for the new Atlas. In addition, there are 153 “specialty blocks” that have unique habitat, are of high conservation value or are of particular interest to ornithologists.

Today, Berkelman is recording his data the old-fashioned way: with pen and notebook. Later, he can plug his observations into Atlas eBird, an online checklist program that is a direct conduit to the database that is the bedrock of the Wisconsin Breeding Bird Atlas.

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