Shorebird migration nearing its peak in the state
http://dnr.wi.gov/news/BreakingNews_Lookup.asp?id=2894
ASHLAND - With summer waning, migratory shorebirds are now reaching peak numbers in Wisconsin and many public properties offer great places to view these birds, traditionally among the first to leave the state for warmer climates, state bird experts say.
“Shorebirds are notorious for being the earliest southbound migrants, and mid-August typically represents peak diversity and abundance of the birds in Wisconsin,” says Ryan Brady, a Department of Natural Resources research scientist who coordinates bird monitoring activities across the state. “To help the public find them, a map has been created showing prospective sites around the state where biologists have created the habitat the birds need to rest and fuel up for their long flights.”
Known locations and their access can be found on this interactive map.
“As of early August, the site known to be providing the best shore bird watching is along Highway 49 at the north end of Horicon Marsh National Wildlife Refuge, although habitat conditions are dynamic and more hotspots no doubt await discovery,” Brady says. Birders are asked to submit their sightings to Wisconsin eBird so that biologists can track migratory shorebird populations and assess the value of these management activities.
Providing bed and breakfast for nearly 40 species of shorebirds
The migratory shorebirds, including nearly 40 species of plovers, sandpipers, phalaropes and their relatives, require specialized and sparsely distributed wetland habitats such as mudflats, shallow water, and exposed sandbars, Brady says.
While a handful of these nest in Wisconsin, the majority only make pit stops here as they wing their way for thousands of miles from nesting grounds on arctic tundra and in boreal forests to wintering areas from the Atlantic and Gulf Coasts of the U.S. to as far south as Argentina.
“Having appropriate stopover habitat for these birds to rest and refuel – sometimes doubling their body weight in just days – is critical to survival of individual birds and overall health of populations,” Brady says.
Natural occurrence of these habitats is scarce and unpredictable. As a result, DNR and other conservation partners create additional habitat at select public properties each year through water-level management, according to Jason Fleener, DNR wetland habitat biologist.
Beginning in late April or early May, wildlife biologists open water control structures to slowly reduce water levels in impoundments. The goal is to expose new mudflats every week based on recent weather conditions and precipitation amounts. This timing coincides with the spring migration of shorebirds as they head north to their summer breeding grounds.
“Mudflats can also be created naturally during dry periods as wetlands evaporate,” Fleener says.
In other instances, impoundments are purposely drained when the condition of dams is deemed unsafe after safety inspections. Drawdowns are also implemented in the summer to coincide with the shorebird migration south to wintering grounds.
By the end of summer, the reduction in water levels results in large, expansive mudflats and a flush of new annual plant growth. After most shorebirds have migrated south in the late summer, biologists will often raise water levels on impoundments, depending on management goals of the site. An important benefit of this management is the large volume of seeds produced by these annual plants. These seeds are consumed en masse by waterfowl, wetland birds and sparrows during fall migration after many of the shorebirds are long gone, Fleener says.
This water level management also helps to regenerate bulrushes and other emergent plants that grebes, coots, rails, ducks and other wetland dependent species use for nesting habitat the following years.
Funding for this habitat work is usually provided by hunter license dollars, excise taxes on hunting and shooting equipment, through the state waterfowl stamp, and private funds. “If you value this type of habitat management and recreational opportunity, please consider purchasing a waterfowl habitat stamp at your local license agent to fund important projects for shorebirds and other non-game wetland birds on state lands,” Fleener says. “Until then, enjoy the birds!”