Scientists are using baby eagle blood to assess the health of Michigan’s environment. Because eagles are top predators, heavily linked to lakes and rivers, they provide a proxy for water quality.
To do this research, eagle biologists Bill Bowerman and Mike Wierda work their way through Michigan, following GPS coordinates for a bald eagle nest that has been located during aerial surveys earlier in the year.
“You certainly get to see a lot of, a lot of corners of Michigan you wouldn't normally when you're out chasing these birds,” said Wierda.
Buckled into the back seat, next to the snack cooler, is a giant blue plastic liquid nitrogen cooler. It has vials of baby eagle blood that have been cooled to minus 70 degrees.
Wierda and Bowerman grew up in different parts of Michigan, both on lakes. But now they're based at different out of state universities. Bowerman is a professor at the University of Maryland and Wierda is with Utah State University. They meet up every spring and summer to survey eagle nests.
The last two years have been a little different. The federal funding that was awarded to monitor the health of the eagles and other waterbirds has been held back. So Bowerman and Wierda are here on this day in central Michigan as volunteers.
Part of their research involves collecting eagle blood. It acts as a concentrator for contaminants from the water, things like DDT, PCBs, PFAS and mercury. With the eagles each having a distinct territory too, the long term data allow the scientists to monitor the health of the ecosystem both in time and among different regions. The baby eagles are called nestlings or eaglets.
“The trends in those populations are very important for knowing about the health of the aquatic environment,” said Bowerman.
He parked the car and led the team down a trail. The team is following a GPS point from aerial surveys using planes that fly over the forests in Michigan to assess the status of the eagle nests. So as they got closer to the GPS point, they left the trail and dispersed into the woods, disappearing alarmingly fast into the brush, in search of the nest.
Bowerman moved through the underbrush with the ease of someone walking their dog on a Sunday afternoon, seemingly immune to branches, thorns and the threat of ticks. This part of the research involves being an eagle detective. They’re looking for clues on the ground and in the trees, like signs of eagle excrement called, “whitewash,” or clumps of branches high up.
After a few minutes of searching, the nest was found. From the ground, it looked like Big Bird could sit comfortably in it. Eagle nests are typically five to eight feet across. With the nest located, Wierda began to suit up. He prepared extensive climbing and safety ropes to solo climb the 70 feet up the tree. The plan was, once he was up there, he would scoop each eaglet into a bag and lower it to the ground.
“When I get to the nest, the babies are great 'cause they hold their wings up as big as they can, they stand up as tall as they can and they go, "Aw, aw, aw," said Wierda. “The eaglets, they’re adorable every time.”
As soon as he started climbing, two adult eagles appeared in the skies with the classic eagle chirp. But the scientists noted that they weren't making as much noise as usual.
It took about an hour for Wierda to reach the nest. Once he got there, he found it empty. This was a shock to the team.
“What a bummer. I had angry adults hanging around. We've got a whitewash down here. It was promising,” said Wierda.
It's unclear what happened exactly. Two weeks ago, aerial surveys had recorded two eaglets in a nest here. Not many predators can reach a nest like that, except maybe a bear, said Bowerman. Could a windstorm have swept them out? They started walking around the base of the tree, looking for bodies. Or maybe we were just at the wrong tree. Maybe there was another nest nearby. The group of woodsmen set out to search.
They came back with nothing. Bowerman said it could be a combination of factors; “the other possibility here is in the last 12 days they starved to death…. We really haven't seen anything like this.”
And that's saying something because he's been at this a long time. Bowerman said, “My project started in 1961,” and Bowerman himself has been working on it since 1984.
“Because we could not get our federal funding, we created a nonprofit called Wings Over Water Research Institute.”
Both Bowerman and Wierda are associated with Wings Over Water. The nonprofit works to support continued eagle research, in an effort to maintain the long term data set, and understand the health of the eagles and the environment. In past field seasons, they recorded losses of eagles due to bird flu. A 2020 paper in Environmental Pollution from their research was published as the first of its kind in testing eagle eggs for PFAS.
The scientists hope to use this data to continue to investigate environmental mysteries about eagle health and water quality.
