For many people in New Hampshire, loons are the sound of summer.
In the fall, male loons are the first to depart for the Atlantic Ocean where they spend the winter on open water along the coast.
The female of the pair typically remains behind with the fledglings. They may not leave for the winter until the lakes finally begin to ice up.
For Jen Esten and Jon Wagge, of the Pleasant Lake Protective Association, watching and photographing the loons of Pleasant Lake has become a long-running study in wildlife behavior and survival.
They chronicle the lives of the loons and other creatures and phenomena that make up the lake ecosystem in the newsletter: “The Nature of Pleasant Lake.”
Esten began photographing the lake’s loons in 2007. Wagge is a retired professor of ecology and evolutionary biology.
An extraordinary loon
The resident loon on Pleasant Lake is a female, banded in 2001 as a chick on Squam Lake, making her 25 years old.
“She’s a remarkable loon,” Wagge said.
Esten said the bird has earned something of a celebrity reputation among people who follow New Hampshire’s loons. Loons can live into their 30s, and this female has had remarkable success raising young.
According to Esten, over the last two decades the loon has raised 25 chicks to the point of fledging, well above the state's average, where roughly one chick survives every two years of nesting.
The female's longtime mate, however, disappeared after 17 seasons on Pleasant Lake, failing to return from the ocean in 2024.
He had been banded as an adult in 2010, so his exact age was unknown. He was immediately replaced by another male loon.
Banding also helps reveal how the birds connect to lakes across the state. Esten and Wagge know of three loons that hatched and were banded on Pleasant Lake that have since set up residence on other lakes in the state.
Life on the lake can be brutal
Loons may seem serene as they glide across a lake, but they must constantly defend their territory.
When rival loons challenge one another, fights can be deadly. The birds use their sharp bills as weapons, sometimes rising from beneath the water to stab an opponent in the chest.
Their success at raising chicks can depend on weather and luck.
New Hampshire residents are familiar with the scourge of black flies, and loons have a particular species of black fly that plague them on the nest.
Esten says if the flies become bad enough, a loon may be unable to sit on its eggs for more than a few minutes, especially in hot weather. That leaves the eggs vulnerable to predation.
Esten recalled a year when excessive heat caused two eggs to be lost, and other parts of New Hampshire reported similar problems.
What a loon is saying
The haunting wail of the loon is easy to hear across a quiet lake at night, and is how the loons locate each other.
But other calls communicate something different. Up close, loons also make soft hooting sounds, checking in with each other and chicks.
A tremolo, the distinctive crazy laughing sound, can serve as a warning when a loon feels threatened or disturbed.
The yodel is made exclusively by a male, and is a territorial call and a threat warning.
A loon might sound an alarm if an eagle or a paddleboarder with a dog get too close.
Photographing loons
Getting too close and alarming the loons means they have to spend energy in defense, rather than looking for food or tending to chicks.
Thanks to years of careful observation, Esten and Wagge can recognize individual birds, and through their newsletter they share the lives of the loons and the challenges they face.
To hear more loon calls and to learn more about them, visit the Loon Preservation Society’s website at loon.org.
Something Wild is a collaboration between the Forest Society, NH Audubon, and NHPR.
