Temperatures plummeted beneath a black dome of sparking stars. As the eight inches of ice already on the lake thickened and expanded in the cold, it sang the eerie notes of winter. A couple weeks ago the ice-notes were high and squeaky – shorter frequencies due to thinner ice – but tonight they deepened into the lower moans of thick ice. The ice’s plaintive wails brought to mind the lake songs of summer – as performed by loons.
All summer long we alternately curse and acclaim their calls. One grumpy (and tired) visitor asked me “Do loons ever sleep?” after nearby birds had caterwauled into the wee hours of the morning. Although they do sleep, it’s not on our schedule. Since loons are visual hunters, they must feed when sunlight penetrates into fish habitat. When darkness brings relative quiet to the woods, they use that opportunity to communicate with neighbors.
“Who’s there? I’m here,” may be the basic message in their wail. By speaking up, each loon reasserts that it is on its territory, and ready to defend against invaders. If a loon remains quiet, that could signal that its territory is free for the taking, a risky message to convey. As male loons patrol their territory boundaries each night, encountering a another male intruder will trigger a yodeling contest. That’s the maniacal cry, called “the laugh of the deeply insane” by writer John McPhee, that you curse might at 3:00 a.m. It may or may not result in a physical battle.
Where are the loons now, though? I haven’t heard them calling since late summer, or seen an adult in quite a while. The last loon I saw was the sole surviving juvenile from a nest in a nearby bay. With any luck, he was able to gain enough strength to migrate south by November 14, when the lake started to freeze.
There’s no way of knowing where my particular unmarked loon neighbor went, but the United States Geological Survey (USGS) has captured and radiomarked several juvenile loons on lakes scattered across Minnesota and Wisconsin. Researchers use geolocators and satellite transmitters to track the movements of migrating and wintering loons. From their data, we can watch the juvenile loons move south in almost real-time, on animated maps.
As with most years, the 2014 juveniles began their journeys from late October to mid-November. It looks like a few loons headed south just ahead of ice-up! Their routes aren’t identical, but some juvenile loons made a layover on Lake Michigan. Others made pit stops on the Mississippi River or reservoirs in the central states. The juveniles must make the trip alone, since their parents and non-breeding adults migrate earlier. In general, non-breeding adults start migration in late August, mothers leave in September, and fathers head out in October.
The ultimate destination for many of our Wisconsin and Minnesota loons is the Gulf of Mexico, and specifically the west coast of Florida. Their main habitat requirements are plenty of fish to eat and clear water to hunt in. Southern inland lakes tend to have warm, shallow, murky water, and alligators (!), so the ocean provides a better option. There, loons face the challenge of transitioning from freshwater to saltwater. They’ve adapted by excreting salt out of glands in their skull between their eyes. The glands drip almost constantly during the winter…sort of like how my nose adapts to winter, too…
After making the big journey and coping with salt, loons gain access to a seafood feast. Wintering loons eat flounder, crabs, lobster, shrimp, gulf menhaden, bay anchovies, silversides, and more. The ocean bounty gives loons enough energy to molt and regrow all of their feathers, but danger is still present. Not much is known about loon predation in the ocean, but I’ve heard that dog sharks will race upward through the water to attack loons from below.
Unfortunately for human snowbirds, the loons’ winter feast doesn’t happen within viewing distance. Most loons spend the winter at least five miles (and often much farther) offshore. Even if you could see the loons, you might not recognize them. The adults and juveniles all wear drab brown plumage, and sport dark eyes instead of the ruby red eyes of breeding season. They aren’t known to vocalize. In the spring, adults molt back into breeding plumage, complete with red eye. Juveniles stay brown and ocean-bound while they mature, and will only migrate back toward their natal lake after they are three to four years old.
Loons need to winter on the ocean, but I am grateful that human adaptations allow me to enjoy my northern lakes all year round. When the haunting calls of the loons fade with the summer sunshine, the lake itself sings an icy winter tune. Perhaps it, too, is asking “Where are the loons?”
For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! The current exhibit, “Nature’s Superheroes—Adventures with Adaptations,” opens in May 2014 and will remain open until March 2015.
Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com.