Multi-partner study sheds light on trumpeter swans, a species back from the brink
A doctoral student at the University of Minnesota, David Wolfson is leading a multi-year study to fit about 40 trumpeter swans across the state with GPS tracking collars this summer to learn more about their movements, mortality risks and habitat use. Working with him is wildlife technician Tori Drake, a Bemidji State University graduate.
ROSEAU RIVER WILDLIFE MANAGEMENT AREA, Minn. – David Wolfson and Tori Drake were on the home stretch of a summerlong research project, and they’d budgeted one day to catch a trumpeter swan and fit it with a GPS tracking collar in this massive WMA that tickles the Manitoba border in northwest Minnesota.
If they failed to catch a swan, they’d move on to a different part of northern Minnesota.
There were trumpeters in the area – they'd spotted 17 swans, about half adults and half cygnets, as juvenile birds are called, the previous evening – but catching one of the majestic birds in its home habitat isn’t always easy. Especially in an area the size of Roseau River WMA, which covers more than 75,000 acres.
In reality, it took Wolfson and Drake maybe 10 minutes from the time they left shore in the 14-foot jon boat they use for their research until they emerged through the break in the cattails with a trumpeter swan. A picture of grace and beauty, the swan was surprisingly docile in Wolfson’s arms as Drake steered the “mud motor” designed to navigate shallow water back to shore.
Which begged the question: Is catching a trumpeter swan always this easy?
“For the most part, yes,” laughed Drake, a wildlife technician and graduate of Bemidji State University.
Well, it can be, Wolfson said, adding a caveat:
“Provided you’ve spotted a swan, obtained permission to access the property, are able to drag the jon boat to open water and are lucky enough to encounter a swan that is molting.”
It isn’t always easy, in other words, but it’s nice when it is.
A doctoral student at the University of Minnesota, Wolfson is leading a multi-year study to fit about 40 trumpeter swans across the state with GPS tracking collars this summer to learn more about their movements, mortality risks and habitat use.
Sporting collar 5E, the mature female at Roseau River was trumpeter swan No. 36 for the summer; Wolfson and Drake would wrap up the collaring effort a few days later in northeast Minnesota.
The study is a partnership between the Minnesota Cooperative Fish and Wildlife Research Unit of the U.S. Geological Survey and several collaborators, including the University of Minnesota, the U.S. Fish and Wildlife Service, the Minnesota Department of Natural Resources, the Twin Cities-based Three Rivers Park District and the Trumpeter Swan Society.
In the very simplest of terms, the study aims to build on the knowledge of the so-called “Interior Population” of trumpeter swans, which includes Minnesota birds, and their remarkable story of recovery from the brink of extinction.
Little is known about the migration patterns of trumpeter swans in the Interior Population, Wolfson said. Among the questions he’s seeking to answer are how likely they are to migrate, how far they travel and where they winter.
“An important aspect of the ecology of wildlife species is to understand annual movements and migration pathways," Wolfson said. “That can help you make management decisions and understand how to conserve animal species.”
The study also is looking at lead concentrations in every collared swan to gauge the effects of lead exposure, Wolfson said, along with evaluating the genetics of the Interior Population, which was restored by a multitude of reintroduction efforts across the Midwest.
Coupled with similar studies underway in Michigan, Ohio, Iowa, Wisconsin and Manitoba, researchers will be able to track about 100 swans fitted with the GPS collars, Wolfson said.
“We're catching swans across basically almost the entire breeding range of the Interior Population, and so we’ll be able to have a much more representative idea of what’s going on across the population,” he said.
The collars, which cost about $1,200 each, capture data points every 15 minutes and download the information to a cell tower either daily or whenever cell service is available.
“Connections can be sparse, but (the collar) can store a lot of information onboard the unit and then transmit the batch once the collar is within reception of a cell tower,” Wolfson said.
Eventually, findings from the study will form the basis for Wolfson’s doctoral thesis.
Story of recovery
According to the Minnesota DNR, trumpeter swans historically flourished across North America from Illinois northwest to Alaska. But market hunting, driven by demand for the birds’ meat, skin and feathers, along with habitat loss as settlers moved across the region, led to population declines.
By the 1880s, trumpeter swans had disappeared from Minnesota, and by the 1930s, only 69 trumpeter swans remained in the lower 48 states, the DNR said, living in the remote Red Rock Lakes wildlife refuge of southwestern Montana.
“People thought those were the last ones left, and then years later, they found a wild population in Alaska that was pretty sizable,” Wolfson said.
Minnesota's efforts to reintroduce trumpeter swans began in the 1960s, when what today is known as the Three Rivers Park District got 40 swans from the fledgling Montana population. In the 1980s, Minnesota's Nongame Wildlife Fund – funded by a checkoff on Minnesota tax forms – got a permit to collect 50 eggs from Alaska.
Thanks to those and subsequent reintroductions, Minnesota's trumpeter swan population has grown as much as 20% annually since 2000, based on observations from annual Minnesota waterfowl surveys, and today numbers about 30,000 birds, the DNR says.
Catching the swans
As with many bird species, trumpeter swans go through a molt every summer to replace their flight feathers. During that period, which usually begins in July and continues into August, the adult swans can’t fly.
That makes the birds easier to catch, and Wolfson and Drake have captured and collared trumpeter swans from nearly every region of Minnesota.
Ideally, they target breeding pairs with cygnets, Wolfson said.
“Typically, at least one adult is in molt during this time of year, so we'll approach the pair,” he said. “Usually, the one that’s not molting will fly, and then the other one uses its wings to kind of swim and flap away. But we’re faster than the swan is so we can just kind of boat up to it and catch it, and it’s all pretty quick, pretty easy.
“When it works well, it works well.”
Working during a pandemic hasn’t been difficult, Wolfson said. They’ve traveled in separate vehicles, wore masks and spent more time staying in hotels instead of onsite lodging where they work, he said. Overall, the pandemic guidelines haven’t hampered their time in the field.
“It hasn’t been as bad as I feared,” Wolfson said. “As far as what we’re doing, we’re outdoors, we’re in remote settings, and we’re not really interacting with people. The two of us take a lot of precautions around each other, but other than that, it hasn’t been too bad.
“I kind of thought they would cancel the whole field season, but they didn’t.”
With this year’s field season complete, Wolfson and other project partners will continue to collect data and analyze results throughout the duration of the four-year study.
The Minnesota Environment and Natural Resources Trust Fund is funding the project, as recommended by the Legislative-Citizens Commission on Minnesota Resources, along with the U.S. Fish and Wildlife Service and others.
On the Web:
More info on the study is available on the project website at https://trumpeterswan.netlify.app/index.html . The site includes updates, annual reports and a map showing the locations of the collared study birds.
Dokken reports on outdoors. Call him at (701) 780-1148, (800) 477-6572 ext. 1148 or send email to firstname.lastname@example.org .