Migrating birds pile up along Great Lakes' shores

Date: December 7, 2016

Source: Central Ornithology Publication Office

Birds prefer to migrate at night--so much so that if day breaks while they're over water, they'll turn back toward the nearest shore rather than pressing on. That's the key finding of a new study in The Auk: Ornithological Advances, which used weather radar to examine the behavior of birds crossing the Great Lakes.

Kevin Archibald and Jeff Buler of the University of Delaware and their colleagues turned the U.S.'s powerful network of weather surveillance radar stations on birds heading north across the Great Lakes during their spring migration. As dawn approaches, their data show, birds caught over water increase their elevation and often turn back. This leads to a pileup of birds in near-shore stopover habitat--the density of birds taking off from the southern shores of the Great Lakes on subsequent spring evenings was 48% higher than on the northern shores.

Birds presumably increase their altitude at dawn to try to see how much farther they have to go; if they decide it's too far, they go back to try again the next night, leading to higher concentrations of migrants on near shores. When birds are migrating south in the fall, these pile-ups would happen on the north side of the lakes rather than the south. "Our study justifies the high value of shoreline habitats for conservation of migratory bird populations in the Great Lakes region," says Buler. "It also emphasizes that the extent of stopover use in shoreline habitats is context-dependent. We hope professionals charged with managing stopover habitats recognize that shoreline areas can receive high migrant use by virtue of the proximity to a lake and how many migrants are aloft at dawn from day to day, rather than [just] by the presence of abundant food sources in these habitats."

The data used in the study came from radar stations in Cleveland, Ohio; Grand Rapids, Michigan; and Green Bay, Wisconsin, collected in spring 2010-2013. Cleveland was the only station that did not observe birds increasing their elevation at dawn, possibly because Lake Erie is narrow enough for them to see across without an increase in altitude.

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Longest study of Great Lakes region birds finds populations holding steady

Date: July 12, 2016

Source: USDA Forest Service - Northern Research Station

A new USDA Forest Service report documenting an unprecedented effort to inventory birds in the western Great Lakes region and analyze changes in bird populations over the past quarter of a century found that across a trio of national forests, most birds are doing well in terms of both species diversity and population.

Published as General Technical Report NRS-159, "Analysis of Long-term Forest Bird Monitoring Data from National Forests of the Western Great Lakes Region" describes trends and potential drivers in the abundance of bird species. Gerald Niemi of the University of Minnesota-Duluth's Natural Resources Research Institute and Robert Howe of the University of Wisconsin-Green Bay are lead authors of the report with co-author Brian Sturtevant, a research ecologist with the USDA Forest Service's Northern Research Station. An estimated 700 birders have volunteered their time or worked as paid field researchers to inventory bird species for more than 25 years. The report will serve as a useful reference for forest managers identifying how species respond to forest management and what species need attention.

"Forest Service science is contributing to healthy, sustainable forests that are more productive and, ultimately, produce cleaner air and water," said Tony Ferguson, Acting Director of the Northern Research Station and the Forest Products Laboratory. "Forest birds play a vital role in forest stewardship through seed dispersal and insect control, and this research will be a valuable reference for land managers working to protect critical habitat for forest birds."

In the three national forests covered by the inventory -- the Chequamegon-Nicolet National Forest in Wisconsin and the Superior and Chippewa National Forests in Northern Minnesota -- the analysis found overall healthy bird communities that give researchers and policy-makers a degree of optimism. "It paints a picture of fairly healthy bird communities in these forests over two decades of surveys," said Niemi. "It shows that there is tremendous diversity of bird species in the region and emphasizes the importance of national forests to migratory and resident bird species."

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Great Lakes Waterfowl Die-Offs: Finding the Source

Nov. 24, 2013 — A deadly menace stalks the loons, gulls, and other water birds of the Great Lakes region: Type E botulism, a neuromuscular disease caused when birds eat fish infected with toxin-producing bacteria. Cases of the disease are on the rise, killing approximately 10,000 more waterfowl in 2007 than when it was first reported in 1963.

To understand die-off origin and distribution, ocean engineers from the Florida Atlantic University (FAU) Institute for Ocean Systems Engineering in Dania Beach, Florida are using their expertise in experimental hydrodynamics. They have teamed with the U.S. Geological Survey to help develop a novel way of tracking waterfowl carcasses to determine the source of lethal outbreaks that infect fish eaten by waterbirds.

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