Dennis Anderson: Officials catch and release, and learn from loons

CROW WING COUNTY, MINN.

If we had been on a mosquito hunt, motoring across a darkened lake in north-central Minnesota, rather than a search for loons, our success would have been guaranteed.

This was about 10:30 Tuesday night, and Steve Houdek, a biological technician with the U.S. Geological Survey in La Crosse, Wis., was piloting a 16-foot aluminum boat, while two of his colleagues, biological technician Luke Fara and research wildlife biologist Kevin Kenow, crowded in the boat's bow, with Kenow pointing a high-powered spotlight into the black night.

So far the beacon had illuminated only countless flying bugs, including the biting kind.

Also in the boat were Department of Natural Resources non-game wildlife program supervisor Carrol Henderson, and me.

The goal: To capture a nesting pair of adult loons and their lone chick, and bring them to shore, where blood and feather samples would be drawn, and special "geolocators'' attached to a leg of each adult would be removed, so migration, diet and other information the gadgets had recorded could be downloaded.

Apprehending at least half of the 42 northern Minnesota loons fitted with the recording devices last year is an important part of a study to determine whether loons that nest in Minnesota but winter along the coast of Louisiana and other Southern states were harmed by the 2010 Gulf oil spill.

But no information can be gleaned unless the birds are captured, and so far this summer, Kenow and his crew have been beset by bad luck.

"If a loon pair has one or two chicks, our capturing success rate is about 95 percent,'' Kenow said. "But when the chicks have been lost, as has occurred with some of our study birds this summer, capturing adults is more difficult. The chicks help keep the adults on the surface. Without them, the adults dive.''

On one study lake this summer, a wind storm wiped out 11 nesting platforms, as well as the chicks being raised on them.

So capturing loons on the three Crow Wing County lakes that Kenow's crew would visit Tuesday night was important.

Aiding their effort in locating the birds was an iPod and speaker, over which various loon calls could be played, including the wail, the yodel, the hoot or other variations of the haunting song that is unique to Minnesota's state bird.

As Henderson spoke, stars flickered overhead and a half-moon glowed against the black sky.

Beneath these, Houdek guided the boat slowly, but directly, toward an adult loon. Bedazzled by the light, the bird allowed the boat near it, and in a flash, Kenow scooped it into an oversized fishing net.

Then he and Fara secured the bird so it couldn't harm itself or them, before placing it in a large plastic container, its top punctured with air holes.

Soon the second adult loon also was captured, and then the chick, a bird of perhaps 6 weeks whose size rivaled that of an adult blue-winged teal.

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A sort of portable operating room was soon set up, with headlamps providing most of the light. One by one, the three birds were secured on their backs to have the blood and feather samples removed. The adults also had their geolocators taken off and stored for transport to La Crosse. And each bird was fitted with an identification leg band.

None of this comes cheap.

Paid for by the Environment and Natural Resources Trust Fund with state lottery-sales proceeds, the three-year project will consume $250,000. The effort is overseen by Henderson, and is cooperative between the DNR and the U.S. Geological Survey.

Henderson said that next year he'll apply to the Legislative-Citizen Commission on Minnesota Resources (LCCMR), which advises the Legislature on the lottery fund, to continue the project, which also includes American white pelicans.

"We need to determine whether Minnesota's nesting loons and its pelicans were affected by the oil spill, and if so, how,'' Henderson said. "There is the potential for recovering damages if harm to the birds can be demonstrated.''

The dives might last as long as 2.5 minutes.

"We're worried that in the Gulf of Mexico much of the oil residue and the dispersant used to break up the oil have collected on the ocean bottom, where loons feed,'' Henderson said.

Valuable as the geolocators have been to the study, they aren't perfect. One problem: The adhesive that holds the gadget to a loon's leg occasionally has failed, resulting in loss of the $1,000 recorder and data it collected.

In similar studies with ducks, external transmitters that relay information to a satellite have been used.

"But diving birds like loons don't tolerate external transmitters very well,'' Kenow said. "We could implant the transmitters, but it's an expensive process, and it has to be done surgically.''

The birds were set free in the territory the two parents had established this spring.

This was about midnight, and for Kenow and his crew, more work awaited.

Loons on two more Crow Wing County lakes required their attention. And the next night they would attempt to capture loons on two lakes farther north still, near Ely.

"Minnesota has only about 12,000 loons, and we're the only northern state that's tracking this potential problem,'' Henderson said. "Loons are our state bird. What happens to them is important.''

Dennis Anderson danderson@startribune.com