The mournful wail of a common loon echoes across the glassy water. From a neighboring lake, another loon replies with the same smooth cry. Common loons are an icon of the northwoods, and while it’s not always easy to see one up close, we can enjoy their unique voices from afar. With just a little practice, one can learn to identify loons’ four different calls and attempt to interpret what they’re saying.
Loons use their eerie, howl-like wail as a form of long distance communication. For instance, one loon in a pair might use wail to call their mate back to the territory. During breeding season, the avian parents split childrearing duties 50-50. After the male chooses the nest location, the female builds the nest (which only entails pulling some weeds around her body) and then lays the two eggs. Alternating incubating and eating, the parents wait 26-31 days until the two eggs hatch a day apart. If one member needs a break, or if a threat on their territory is making them nervous, they can call their partner back with a wail.
If eagles come near, the parents may give a special three-note version of the wail. Bald eagles are a known predator of loons, and the alarm call tells the chicks to “DIVE NOW!”
Adult loons communicate with the chicks using a soft, short “hoot.” Snack time often involves the parent surfacing with a minnow, giving a hoot to alert the chick, and the chick swimming over to receive its treat. Loons can’t chew or tear their food, so each lunch item has to come in a bite-sized package. Feeding lessons start with a dead minnow dropped in front of the chick, progress to larger stunned prey, and eventually result in chicks catching their own. I’ve watched as patient parents re-catch a snack and bring it back to the chick for a second attempt.
Not all loon calls are family-friendly, though. The evening serenade of loon calls echoing from lake to lake is one of the most special memories one carries home from a canoe trip. And while it’s true that a couple of those loons might be dedicated mates, there’s also a good chance that some voices belong to rivals.
Loons are extremely territorial, and each pair defends an area with the nesting habitat, protected nursery bays, and feeding grounds that it needs to survive and raise young. While the size of the territory can vary based on the density of food, one thing that remains constant is the need for a clear viewshed. Loons do not like to see other loons while they are on their territory. As a result there are a finite number of loon-ready lakes in the northwoods. Loons who haven’t secured their own territory yet are always on the alert for an opportunity to get one.
During that evening chorus, the neighbors are checking in with each other. Is everyone alive and well, and in their proper location? Or is someone missing? Silence from a lake that used to have a loon on it may invite floater loons to check out the situation for a possible invasion.
The tremolo is another common call you’ll hear from loons. It’s no surprise that this fast, frantic trill is their alarm call. It could mean that a raccoon, a rival, or a human is approaching too close. But it has another use, too.
Loons sometimes make the tremolo call in flight. High in the sky it acts as a doorbell. An exploring loon will tremolo over a lake. If the lake is empty, or if any loons on it are also floaters and not territorial, they will remain silent and the flying loon may land without conflict.
If the lake is occupied, the resident male will signal that he is willing to fight for this prime real estate and he will reply with a maniacal yodel. The invading loon can tell by the lowest note in the resident male’s yodel approximately how big the defender is, and use this information to decide whether a fight is in his favor or not. If he chooses to fight, the invader replies with his own unique yodel. Loons can tell each other apart by their calls, and even elementary students can distinguish individual loons by looking at sonograms of their yodels.
Sometimes the still night air is pierced by the yodels of two male loons. This signifies a battle over territory. Thirty percent of the time a territorial battle results in the death of the resident male. Home territory means a lot to loons. The longer a male holds in the same territory, the more local knowledge he gains about good nest sites, and the greater his chance of raising chicks to adulthood. Finding a new territory isn’t easy, so it’s better to fight hard to keep the one he has. Invading loons have less to lose, so they will give up before mortal injury occurs and live to fight another day.
If the invading male wins, the resident female will stay on the territory with the new male. As with many species, males only fight males and females only fight females. Females don’t yodel, though, and they rarely fight to the death.
The eerie wail, the soft hoot, the frantic trill and the maniacal yodel: drama unfolds as these elements of loon language echo over summer in lake country.