A northern pintail flies above feeding ducks at the Chautauqua National Wildlife Refuge. Photo by Chris Young.
Waterfowl numbers set records
January 02, 2014 at 04:38 PM
Waterfowl migration along the Illinois River was short but intense this fall, with several species of ducks stopping over in record numbers.
The State Journal-Register
At the height of migration, northern pintails, green-winged teal, gadwall and northern shovelers crowded into refuges in the highest numbers recorded in 65 years of aerial surveys.
The Illinois Natural History Survey conducts aerial surveys of 23 sites along the Illinois River and 16 sites on the Mississippi River each week during fall migration. Waterfowl scientist Aaron Yetter conducts the counts.
The survey dates back to 1948, when waterfowl scientist Frank Bellrose started using an airplane to survey ducks and geese.
The survey does not seek to count every duck, but by visiting the same sites each week, scientists can track migration trends and see how well various habitats are supporting migrating birds.
What they saw in the Illinois River Valley this fall was historic.
At migration’s peak, 329,590 mallards were counted, the highest number since 1999.
Northern pintails (141,840), green-winged teal (179,620), gadwall (146,300) and northern shovelers (49,060) were present in the highest numbers since the survey began.
“These were the highest peak abundances and use days that we’ve ever seen here — higher than Frank Bellrose ever saw here, since the beginnings of the survey,” said Heath Hagy, director of the Illinois Natural History Survey’s Forbes Biological Station. “That’s pretty incredible.”
Ducks take flight at the Chautauqua National Wildlife Refuge.
The number of “duck use days” may be even more important than the numbers tallied on a particular survey.
“A ‘duck use day” is one duck in the area for one day,” Hagy said. “We use ‘use days’ to look at habitat carrying capacity. If you have 1,000 ducks for one day or 100 ducks for 10 days, you get the same amount of use and have to have the same amount of food.”
Mallards, for example, racked up 10.6 million “duck use days,” the most since 1999.
Total “duck use days” approached 30 million in the Illinois River Valley.
The ducks aren’t stopping by just for the scenery. Habitat managers try to foster conditions that allow for the production of wetland vegetation that provides food during migration.
Two summers of drought allowed wetlands to dry out so vegetation could grow and produce seed.
Ducks found plenty of habitat and food available in 2012 and 2013.
Hagy said this year’s migration was short, but sweet.
“It was really a truncated migration, at least through this area,” he said. “That was quite a bit different than last year.
“This year, we had higher numbers of ducks for a shorter time. Last year we had really great numbers of ducks but they were really spread out.”
In 2012, ducks remained in good numbers up until Christmas time.
This fall, freezing conditions sent nearly all the birds south by Thanksgiving.
“During the last two years we had phenomenal numbers of ducks but years looked quite a bit different,” Hagy said. “The timing of migration has always been bit different.”
With all the ducks that stopped by, the question remains if there is much left on the buffet when birds start their return trip.
The Chautauqua National Wildlife Refuge had plenty of food, but huge numbers of ducks using it. The peak count there was about 250,000 ducks.
“That’s a lot of pressure on those resources,” Hagy said. “There were a lot of birds grazing it. We certainly hope there is a lot of food left over. That is a big unknown for the spring.
“There will be some decay over the winter, so we won’t be sure until we sample in spring to know how much food is out there.”
To see the weekly surveys in more detail, visit: http://www.bellrose.org.
Wetlands benefit from drought
Wetlands have to dry out from time to time.
“These backwater lakes, especially the shallow ones that would be considered wetlands, need a draw period down every few years or you really lose the integrity of the system as far as waterfowl and aquatic vegetation is concerned,” said Heath Hagy, director of the Forbest Biological Station near Havana. “While the drought was bad for farmers, we saw a great response of aquatic vegetation.”
Sediment in those lake bottoms has a chance to solidify during dry condition, improving clarity when water returns.
“Some of these backwater lakes hadn’t had clear water in 10 years.”
Hennepin and Hopper Lakes in the upper reaches of the Illinois River Valley underwent a restart of sorts to eliminate common carp.
The result was more attractive habitat.
“They were holding 50,000 birds early in season,” Hagy said. “They had clear water down to 10 feet in the ditches.”
Clear water allows sunlight to penetrate so aquatic vegetation like wild celery – a diving duck favorite – to grow.
“And we had good moist soil plants at Lake Chautauqua,” he said. “Those places are really doing a good job.”
The South Pool of Lake Chautauqua is drawn down so wetland vegetation can grow in the summer of 2012.