A team from the Illinois Natural History Survey’s Forbes Biological Station remove lesser scaup from traps in Thompson Lake, part of The Nature Conservancy’s Emiquon Preserve. Photos by Chris Young.
Waterfowl scientists wade into diving duck study
The State Journal-Register
Like an after-hours mosh pit for ducks, the metal wire cages are packed with ducks bobbing up and down on the waves.
The ducks are penned up about 25 yards offshore in three traps designed to easily let ducks in — but not out.
It’s all part of a study designed to determine how well new habitat created along the Illinois River is providing nutritious food for waterfowl — specifically diving ducks, those that disappear underwater to glean their food from the bottom or to grab plants growing just below the surface.
This spring, a team of researchers, students, retirees and office personnel are donning chest waders and long rubber gloves and slogging through the mud and into the waters of Thompson Lake, part of The Nature Conservancy’s Emiquon Preserve in Fulton County. The ducks they capture — mostly lesser scaup and canvasbacks, lured by food — are being weighed and measured to determine body condition and then banded before being released.
A few will have their blood tested. Blood chemistry will tell waterfowl scientists whether the birds are putting on fat during their trip north (good) or burning fat (not so good).
Scientists take blood samples to see if scaup are building fat reserves..
Ducks need to find enough food to help them survive the grueling migration journey and still have enough energy reserves to ensure a successful breeding season.
Rest stops like Emiquon are critical places where ducks and geese can pack on needed calories.
Over the past 50 to 60 years, diving ducks have all but abandoned the Illinois River Valley, opting instead to stage on the Mississippi River near Keokuk, Iowa.
Since water returned to Thompson Lake starting in 2005, migrating birds have returned, making Emiquon one of the most popular stopover spots on the Illinois River.
Studies like this one may help scientists determine if scaup and canvasbacks will once again be able to use the Illinois River Valley in large numbers.
And land managers want to know if their efforts to restore habitat are paying off or if they need to tweak their efforts.
‘All hands on deck’
The study got off to a flying start in late February.
In just five days, the team from the Illinois Natural History Survey’s Forbes Biological Station captured nearly 1,000 scaup.
“I don’t think anyone thought we could capture that many birds,” says waterfowl scientist Randy Smith. “We wanted to spread out over different habitat types, but caught too many at one site.”
Canvasbacks were harder to entice into the traps, although enough were captured to take blood samples.
Besides banding birds in the hand, biologists observed birds on Thompson Lake and other locations to see if they were using the sites to rest, refuel or both.
“The trapping is pretty intense,” Smith says. “We’re getting big trap-loads of birds, and its pretty much all hands on deck when we get them out of the traps and bring them back to the office.”
One of those helping out was Steve Havera, the biological station’s director emeritus.
“It sure beats working,” he says with a smile as the splashing ducks spray him with water.
Smith says ducks are processed as quickly as possible to reduce stress.
Despite the ordeal of being captured and banded, several ducks go right back to the traps after release, the lure of a free meal too tempting to turn down.
Searching for a reason
Smith says the study is patterned after similar studies on Pool 19 of the Mississippi River near Keokuk and other Midwest locations.
Conducting the study in the same way allows scientists to compare results with more confidence.
“The other thing is to compare habitat quality in the Illinois River Valley to these other areas,” Smith says. “If the birds are doing well here, we know the Illinois River Valley is providing good habitat.”
If not, there may be opportunities to switch up management strategies to improve the fitness of the birds by offering additional habitat types that would provide a better variety of food.
One thing that concerns researchers is the drop in the number of scaup — down from 9 million to about 3 to 4 million over the past few decades, Havera said.
Scientists aren’t sure why this is happening. Scaup are hard to study because they nest in the boreal forest of Canada and winter off the Gulf Coast.
They used to be more regular visitors to central Illinois. In the 1950s, Peoria Lake could expect to host 750,000 scaup. Now just a few thousand stop over.
“It is a concern with continental numbers,” Havera says. “They are an international resource, and we are a little bit worried about them.”
Newly restored habitats, such as the Emiquon Preserve, which features Thompson Lake, provide places to stop and rest that had all but disappeared.
“It is expensive to migrate,” Havera says. “We are trying to provide habitat that no longer exists. Now we have a place where they are visiting and feeding well, and it will be interesting to see how they are doing.
“We need to get back to a more balanced system so they have a choice (of places to stop) where they can rest and find food in the fall and spring.”
Birds are released at the Thompson Lake boat ramp.
Heath Hagy, the new director of the Forbes Station, arrived to start his new job right in the middle of the frenzy of trapping and banding ducks.
He dove right in to help, even before his official start date.
“Being around these people and in this historic setting is wonderful,” he says. “Anybody that knows a lot about waterfowl and is very interested probably would have a tough time staying away.”
Chris Young can be reached at 788-1528.
See video of researchers working with ducks at Thompson Lake.
Scaup and canvasback numbers
Greater and lesser scaup are freshwater diving ducks that breed primarily in the boreal forest of Canada extending into Alaska.
They are difficult to tell apart, especially in aerial surveys, so for the purposes of population estimates they are counted together.
Scaup numbers dropped from nearly 8 million in 1972 to about 6 million through 1985. They dropped sharply after that, but have come back somewhat to an estimated 4.3 million in 2011.
Canvasbacks are less abundant, with the 2011 survey estimate at 690,000.
Source: U.S. Fish and Wildlife Service