Layered gray clouds hung low above Lake Jocassee, South Carolina, for our second day of Common Loon research. Despite high winds and heavy rains in the evening forecast, the morning lake was calm enough to be a mirror.
Having explored the flooded stream gorges in the upper lake the previous day, it was our pontoon’s turn to observe loons in the lower lake. Brooks Wade, owner of Jocassee Wild Outdoor Education and our pontoon driver for the day, aimed us toward the twin towers and yellow booms marking the dam built by Duke Energy in 1968.
When the turbines on the dam are in action, loons gather here for a feast of stunned fish. On this morning, all was quiet. Dr. Jay Mager, professor at Northern Ohio University, put a fresh data sheet on his clipboard, and started by recording the water temperature, air temperature, wind speed, weather, GPS coordinates, and water depth.
While Jay was doing that, we all scanned the half-dozen or so loons in the area, trying to select one with plumage that was distinctive from the rest of the group. Then the timer started, and at two-minute intervals for the next hour, we recorded the loon’s behavior and proximity to other loons. Our loon swam and rested placidly, likely digesting a big meal. This hour clearly wasn’t representative of loon behavior overall, which is why scientists are always trying to collect more data.
Motoring over to a narrow section of the lake, we sought out a new research subject. The loon we found had particularly poor fashion sense. On the top of their back were brownish-gray feathers with pale, scalloped edges. This pattern is thought to indicate a juvenile loon. Ringing their body just above the water line were black feathers with white speckles more similar to the adult loons we see up north. This combination, we surmised, might mean that this juvenile was molting into their adult plumage for the first time.
When a young loon migrates south at the end of their first summer, they are expected to stay on the ocean for a few winters to gain strength without the conflicts that occur around nests up north. There are just a few freshwater lakes in the south where gray-brown juvenile loons have been spotted over the summer, and Jocassee is one of them.
While Jay took care of recording data, I offered to be in charge of the stopwatch. When recording time-activity-budgets for loons, you need two timepieces. Jay has an app on his phone that is set to beep at 2-minute intervals for an hour. At every beep, the binocular-wielding observers help the recorder mark down the behavior. Was the loon resting, locomoting, preening, foraging, or being aggressive? And was the loon within 25 body lengths of another loon? How many loons?
My job, with the stopwatch, was to time the loon’s dives. “Down!” everyone blurted when the loon dove. Then we’d stay vigilant, scanning the water in all directions around the pontoon boat until someone spotted the loon resurface. “Up!” marked the end of the dive, and I would tell Jay the time. While loons here have been recorded staying under for up to four minutes, two minutes was an average dive in this location, which the depth finder on the pontoon measured at about 80 feet. My stopwatch was kept busy as the loon dove almost continuously for the entire hour.
A solo loon making long dives in a deep part of the lake (apparently eating big fish near the bottom) fits the pattern that Jay has noticed consistently over the past decade. Loon behavior here seems to be bimodal. The other mode is that in shallow areas of the lake, rafts of a few to twenty loons hang out together and feed cooperatively on “bait balls” or big schools of little fish.
One of the main goals of this research is to compare how loons on the salt-free waters of Lake Jocassee spend their time, versus loons who spend their winter on the ocean. While loons have adapted to living in the ocean by revving up a salt-removal gland the instant they taste saltwater, that gland requires energy to maintain. The ocean can also be a deep, dark, murky place for a visual hunter. So far, researchers on the ocean have found that loons spend 55-67 percent of their time foraging. On Lake Jocassee, the average is 54 percent.
That one number doesn’t tell the full story, though, because solitary loons here spend 64 percent of their time foraging, while social loons only spend 40 percent of their time foraging. Does that mean social loons have more time to rest and preen, important tasks in preparation for migration? Or does that mean they spend their extra time using energy on social interaction?
As our beloved loons face an uncertain future with warmer lakes and shifting habitats, it will only become more important for us to understand their needs across all four seasons. The work done here, on Lake Jocassee, will help ensure that our Northwoods loons return healthy and well-fed each spring.
Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.
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Last Update: Mar 19, 2025 8:51 am CDT
