The Call of the Loons

Story by Jon Christensen

This day really couldn't get going until after nightfall. That's when the loon hunt would begin. The rest of the day was spent getting ready. Not that there was much to do.

Photo by Kit Miller

The scientists had caught 11 loons on Walker Lake the night before. They needed at least nine more birds. The nets and boats and calipers and scales were all ready to go. But you can't catch a loon during the day.

So Mike Yates went fishing from the disheveled dock in front of the rundown cinderblock motel where the team of scientists was staying. The lake was glassy calm.

Larry Neel wrote field notes in the shade of the walkway in front of their rooms. Gary Herron read a John Grisham novel on his motel room bed. Mike Sevon and Chris Drake went out on the lake in a boat to catch fish so they could analyze the diet of the loons. They were all from the Nevada Division of Wildlife, which has long had an interest in Walker Lake. Dave Evers and Kate Taylor, loon capture specialists from New England, were expected later.

They were flying into Las Vegas on their own dime and driving up to join the group with more syringes and test tubes to take samples of loon blood.

Last spring, this team of scientists had begun studying the loons of Walker Lake. Around a thousand loons spend about a month in the spring and another month in the fall on Walker Lake. The loons stop here on their way from, well, the truth is nobody knows from where to where. That was just one of the mysteries that the scientists hoped to understand about the wandering birds with the soulful lonely yodel.

The mystery of the Walker Lake loons began during the drought of the early 1990's. The lake was not getting enough fresh water and it came very close to becoming too salty for fish eggs to survive. Larry Neel, a biologist with the Nevada Division of Wildlife, wondered what would happen to the fish-eating loons if the fish in the lake died.

What would happen to the loons of Walker Lake if they lost their rest stop?

If those loons were unable to survive their journey, would loons suddenly disappear from their breeding grounds on remote lakes in Minnesota or Canada?

Where did the loons of Walker Lake spend the rest of their lives anyway?

Nobody knew.

The scientists did know that common loons in the West spend their summers on northern lakes, where they nest and breed. And they winter on the West Coast, as far north as Tomales Bay, north of San Francisco, and south through Monterey Bay to San Diego, Baja, the Sea of Cortez, and the Pacific coast of Mexico.

But after the scientists caught six loons last spring, the mystery only deepened. They implanted small transmitters just under the skin between the wings on the backs of two of the birds. The transmitters periodically sent a signal to a satellite orbiting the earth. That information was then sent to Mike Yates, who forwarded each bulletin to the others so that everyone could follow the movement of the birds.

After spending a month on the lake, one loon took off for Pyramid Lake, and then was picked up at Flaming Gorge Reservoir on the border of Colorado and Utah. It was headed on a direct course for the boundary waters between Minnesota and Canada. But it was never heard from again. The other loon made it all the way to central Saskatchewan before its transmitter ran out of juice.

Then the blood samples from the six loons came back from the lab with elevated levels of mercury. Three of the birds had mercury levels that were considered lethal. The scientists were alarmed and dug back into earlier fish samples taken from Walker Lake and found some tui chub with mercury levels high enough to debilitate a bird. All of a sudden, what had started as something of a scientific puzzle - to figure out how the loons of Walker Lake were related to other common loons of the West - now had taken a deadly serious twist.

People were quick to speculate about the possible sources of mercury, including mining over the last hundred years in the head waters of the Walker River, around Aurora and Bodie, and manufacturing and testing ammunition at the Hawthorne Army Depot on the south shore of Walker Lake. But six samples, as Mike Yates and the other scientists were quick to point out, is not even enough to know whether there is really cause for concern, let alone point to possible suspects, much less convict a culprit.

So the scientists hoped to capture at least 20 more loons this spring to study the level of mercury in their bodies. They had hoped to get money for outfitting more birds with transmitters so that they could find out if there were other places the birds might have picked up mercury. But they didn't even have enough money to have the blood analyzed. Still they came together on their own initiative to keep this important research alive.

Mike Yates was working on his own time this year to coordinate the project.

And as he ritually cast out and reeled in a silvery spinning lure, a few loons swam just off shore, calling and half-yodeling to each other as if to mock the scientists. One flapped its wings and stood up on the water in an aggressive display of territoriality that is usually reserved for their nesting grounds rather than this mellow way station on their long journey from who knows where to where.

What the scientists do know is that loons stop at Walker Lake to fuel up on tui chub, a small trout-like native fish that grows to around ten inches long. Lahontan cutthroat trout also live in the lake. That's what Yates was halfheartedly trying to catch. Most people come to the lake to fish for cutthroat. But if one could take all of the fish out of the lake and weigh them, about 95 percent of the total weight would be made up of tui chub - loon food.

And loons were what Yates was really after. But you have to wait until dark to hunt loons. So Yates gave up on fishing and joined the others to wait.

Mike Yates is a falconer at heart. He lives in Carson Valley. At 52, he has become a nationally recognized specialist at putting transmitters on birds to study their migrations. Over the years, he has put transmitters in tiny backpacks on thousands of peregrine falcons, and dozens of other birds. But his favorites are the raptors.

And like the birds he studies and loves, Yates is a natural born hunter. But his thing is catching, not killing. He loves to hold the birds in his hands, alive, to see them up close, and know them, then let them free, and watch where they go and what they do.

He was like that as a boy, growing up in the Maryland suburbs of Washington, D.C. If he didn't have to be in school, he was out in the fields and woods, fishing, hunting, looking, and catching any animal he could get his hands on.

If he couldn't just reach out and grab them, like the turtles he caught along the creeks, he would make it a project to figure out how he could get his hands on them. He studied zoology in college. And he became a falconer, first out of passion and identification with the hunting birds, then it became his profession.

Yates has followed peregrine falcons around the world in his work with the Center for Conservation Research and Technology, a private consulting firm that works with government agencies and university researchers. His research has put him on the far frontiers of bird research, using small transmitters and satellites to track birds on their long migrations to the far corners of the globe.

Yates is a lone eagle himself, a researcher who sees his colleagues infrequently during intensive research expeditions, and is otherwise connected to them only by ethereal e-mail from his home in Carson Valley. So it is a real pleasure for him to work with other scientists in Nevada where he feels at home. He savored the subdued camaraderie of the research camp.

Out on the lake, the loons called back and forth to each other. The scientists joked that the loons were plotting against them.

Around mid-afternoon, Mike Sevon and Chris Drake came back with a bucket full of cutthroat trout and tui chub. They measured and weighed and cut fillets from each fish to sample for mercury. They threw the rest to a crowd of seagulls that gathered around the picnic table where the scientists had set up their makeshift laboratory.

The scientists laughed at the gulls and casually analyzed their pecking order as the birds fought over the rich clumps of roe and scrambled for scraps of flesh. But the amusement was short lived. Although the feast was soon over, the seagulls continued squawking noisily.

So the scientists retreated to their rooms to rest. At 7 p.m., they emerged to eat dinner at the Cliff House restaurant above the motel. After dinner, the pace picked up. A strong wind was whipping waves across the lake. The scientists were all dressed warmly, stomping around the boats, aching to get going, when Dave Evers and Kate Taylor pulled in at 8 p.m. just when it was getting dark enough to start the hunt.

The scientists quickly divided into two crews and launched their boats on the black water. Their searchlights pierced the darkness sweeping back and forth as the boats sped out toward the center of the lake. The boats crashed through the waves as the scientists searched for the birds that had mocked them earlier.

About a mile out on the lake, Mike Yates spotted the first loon. He kept the spotlight in its eye as the boat slowed down. The loon froze for a moment then skittered away across the water. The boat followed. But the bird dove under the water and disappeared.

Through the mist Yates spotted another. This time, as Dave Evers softly mimicked the call of a loon, the boat got close enough for Yates to snare the bird in a fishnet. It was wet and heavy, more than 20 pounds of struggling bird. Yates hoisted it aboard, and carefully deposited it in a plastic bin.

The loon called plaintively for help.

When Dave Evers netted a second loon, they headed back for camp. There the picnic table had been turned into a M.A.S.H.-like emergency hospital for loons. Two powerful floodlights illuminated an array of syringes, test tubes, scales, measuring tape, and bird bands.

The scientists struggled with each bird, measured its sharp beak, traced its wings, and weighed it. They felt each bird's heart beating under a white-feathered breastbone. They looked into the red eye of each loon. And took blood from a vein in the ankle of its webbed feet.

They filled three test tubes with blood from each bird. One would be tested for mercury, the other for lead, and the other for stress hormones, because some pollutants may affect the hormones of birds. They clipped a feather to test for long-term mercury exposure.

Holding the birds, Mike Yates felt the same thrill of discovery he felt as a kid when he picked up an animal he had never handled before. He was amazed that such a heavy bird, with such small wings, could fly so far. He thought about how loons run across the water to get up enough speed to take flight.

As midnight came and went, the boats went out and brought back more birds.

Around 1 a.m., the last boat landed with two more loons. Mike Sevon wearily trudged up the beach with a grebe they had found dead on the lake. Fishing line was tangled around its neck. He set in on the table where it stayed while the scientists wrestled with the last loons. It was a reminder of the fragility of life on the lake.

The scientists released the last loon shortly before 2 a.m. It disappeared into the darkness. And they listened as its lonely call faded across the lake.

They were exhausted. But they stopped and took stock. They had caught their 20 loons. They still needed to come up with a few thousand dollars to help to pay for the lab work to determine mercury levels in the loons. But they were keeping the research alive.

They talked of coming back in a year, when they hope to have transmitters to mount on eight loons in the spring and eight more in the fall to see where they come from and where they go after leaving Walker Lake. And Sen. Harry Reid had promised to try to find funding for the research.

Many of the loons they caught this year seemed healthy, feisty, and strong under their hands, ready to take on a long flight. But a few were small, docile, and weak. They might not make it. And this was just the beginning of a long journey the scientists will take to figure out why.

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