As they've done every year since 2003, Bob and Carole Otto approached a spring day in 2017 with the same mission. A couple of days after ice-out, on April 5, they launched a loon nesting platform onto Eagle Lake in Crow Wing County.

Through their binoculars, they watched as a pair of loons took up residence on the platform, which is built to protect them and their offspring from predators.

The loons nested, laid two eggs, and took turns fishing and sitting on the eggs. On May 28, an egg hatched and a chick emerged. The Ottos watched as the adult loons continued sitting on the nest for a couple more days. Then, the adult loons abandoned the unhatched egg May 31.

Bob Otto called state biologist Kevin Woizeschke, who coordinates the Volunteer LoonWatcher Survey for the Minnesota Department of Natural Resources (DNR). Did he have any interest in the unhatched egg? Woizeschke did, so the Ottos retrieved the egg and brought it to his office in Brainerd.

Like so many Minnesotans, the Ottos love loons. They've been part of the DNR's LoonWatcher program since 2006.

"My parents lived on Eagle Lake for 26 years and they always saw loons moving through, but they never saw baby loons on the lake," said Bob Otto. "So we decided to put out a floating nest platform to give the loons a chance to nest on the lake away from predators."

A loon spread its wings on Eagle Lake in Crow Wing County.

The couple built and launched their first platform in 2003. They are also part of an informal network of loon lovers in the Brainerd Lakes area, sharing nesting data through e-mail. Last year was the second time they'd witnessed an egg go unhatched.

"That egg has been on quite an odyssey," said Carrol Henderson supervisor of the DNR's Nongame Wildlife Program. Since 2011, Henderson has overseen a $640,000 grant funded from state lottery money through the Environmental and Natural Resources Fund, sending unhatched loon eggs from Minnesota to the University of Connecticut for study.

As part of a multiagency study that includes the University of Connecticut, Henderson has been analyzing data linking the 2010 Deepwater Horizon oil spill in the Gulf of Mexico to the health of Minnesota loons, many of which migrate there in winter. The DNR has loon eggs, blood, and feather samples from before the spill, and from after an estimated 4.9 million barrels of oil gushed from the ocean floor. There also is oil-related dispersant contamination.

"There is smoking-gun evidence," Henderson said. "Loons are coming back to Minnesota with contaminants they picked up in the Gulf."

Twenty-nine eggs were sent to UConn for study in 2016, but then the money ran out. Forty-one unhatched eggs, including the Ottos' egg from Eagle Lake, were collected but not shipped. Instead, the Eagle Lake egg has been in a freezer in Woizeschke's office, sitting among a menagerie of frozen wildlife, waiting for the final $13,000 needed for the last batch of eggs.

While awaiting funds, Woizeschke sent his wife, Julie, on an errand. She drove the egg to the Wild and Free Wildlife Rehabilitation Clinic in Garrison, Minn., where it was X-rayed.

"The yolk and air cell are visible, with no signs of development," Woizeschke said, "which makes it highly probable that this egg did not hatch because of infertility." Whether that infertility can be tied to the Gulf oil spill will take thorough testing by researchers in Connecticut.

Focusing on restoration

Henderson has big plans for Minnesota loons, which number about 12,000 in the summer across the state's lakes. Having proven the link between the spill and loon mortality and infertility, Henderson is applying for a grant of more than $6 million from the $18.7 billion overall settlement owed by British Petroleum, which leased the rig. If the grant is awarded, Henderson and his team will put together a loon restoration plan that includes shoreline habitat and other points of action. The plan will be presented to the public this summer, approved in October, and the money will arrive next April.

BP reportedly has processed more than 99 percent of about 390,000 claims under the settlement, and hopes to complete the remainder in the coming months.

The plan for supporting Minnesota loons will include coordination with local lake associations, which Henderson calls the "movers and shakers of what happens in loon country." Loon-friendly lakes will be identified, and volunteers like the Ottos will be recruited to launch platforms. Anglers will be encouraged to use nontoxic tackle instead of lead sinkers, which loons consume off lake bottoms, poisoning them with lead.

For their part, the Ottos are going to keep floating their platform nest. "This year we added a roof to the platform to keep the eagles from bothering the loons," said Bob Otto. They launched the platform on the day of ice-out, May 1. Loons were on the nest the next day.

Tony Jones is a writer, editor, and outdoorsman who lives in Edina. You can find him at ReverendHunter.com.