Postcard: Scientists climb into bald eagle nests to measure health of the Great Lakes
Biologists with the National Park Service are in their sixth year of visiting eagle nests on Lake Superior for blood and feather samples that help them monitor the level of toxic pollutants in the lake
Jim Spickler is wearing an orange hardhat and hanging on a climbing rope 100 feet up in a white pine tree on Basswood Island in Lake Superior.
“Good morning, Mr. Eagle,” he says to a fuzzy brown bird sitting on the six-foot-wide jumble of sticks that serves as the eaglet’s nest. Spickler is a wildlife biologist and an expert climber from northern California where he works in giant redwood trees. It’s his job to gently stuff the eaglet into a sack and bring it to the ground for a quick checkup. The eaglet is only seven weeks old, but it’s already the size of a small goose, and it has formidable talons attached to its bright yellow feet.Waiting for Spickler on the ground is Bill Route, an ecologist with the National Park Service’s Inventory and Monitoring Program, which keeps tabs on the wellbeing of plants and animals on Park Service land. Route heads up this survey of eagle nests.“Eagles are a success story,” Route says. “Their numbers are increasing.”
Route says there were no eagles at all nesting on the Great Lakes in the late 1960s, thanks in part to the insecticide DDT, which left the eagle’s eggs perilously thin and nearly wiped the birds out. But DDT was banned in 1972, and eagles started to bounce back. They were removed from the Endangered Species List in 2007.
“We still find traces of DDT in eagles,” Route says. “It’s very persistent. And that’s what we’re worried about: persistent, toxic chemicals that accumulate up the food chain.”
Like some flame-retardant and stain resistant chemicals. The scientists will screen the eaglet’s blood for those, too.
“Eagles are a sentinel species,” Route says. “They get this magnification. Since bald eagles sit on top of the food chain, they get a lot of the contaminant because they eat other organisms that are also contaminated.”
As Route is talking, Jim Spickler descends the climbing rope with the eaglet. They draw a blood sample from the bird and make some measurements. The eaglet hisses at them and makes some klutzy attempts at biting their hands. In minutes, Spickler is on his way back up the rope to put the eaglet back on its nest.
Two adult eagles circle above the trees letting out a steady stream of cries. The sound is surprisingly thin and high-pitched for a bird with a seven-foot wingspan. The biologists say adult eagles can be noisy, but they rarely attack humans. The adults will be back on the nest soon after the humans leave.
A few minutes later, the eaglet is in its nest and Jim Spickler is on the ground.
“It’s a little bit of a feisty chick,” he says as he starts packing his climbing gear. “But that means that it’s well fed and it’s likely to survive. So, mission accomplished.”