Common Loon––an uncommon loon in northwest Alaska

By Kate Persons |

The common loon is the most abundant and well-known loon in much of North America. Their iconic, haunting calls resonate through the boreal forests of Alaska, Canada and the northern United States, and it is their wild “laughter” that inspired the saying “crazy as a loon.The endearing photos of loon chicks nestled on the backs of their parents are taken of common loons, who piggyback their downy young in the style of our red-necked grebes. 

Common loons breed on large lakes throughout Alaska’s forested regions. In the open country of northwest and northern Alaska, large lakes are instead occupied by the closely related yellow-billed loon that nests in tundra habitats. (For information about the yellow-billed loon, see the Birder’s Notebook in the October 19, 2023, edition of The Nome Nugget.)

Common loons need clear water lakes with plentiful small fish and at least a 100-yard runway on the water for takeoff. If such habitat occurs in the eastern forested parts of the region, it is possible that common loons may breed there.

Photo by Kate Persons
SCARFACE – A common loon below Safety Bridge shows what are likely battle scars on its face. Suitable breeding territories are limited and loons may acquire them by “hostile takeovers” in which they injure or kill the previous occupant of the territory. Battles are violent and over the course of their long lives, loons can become quite battle scarred. A study found that both males and females average seven bill punctures from being stabbed during territorial battles.

Although common loons are not regular breeders here, these large and elegant loons can sometimes be seen migrating along the Seward Peninsula’s coast in spring and fall. Occasionally some remain for the summer in coastal inshore waters of the peninsula. In Safety Sound small numbers can be seen regularly in late summer and early fall.

Loons are beautifully adapted aquatic predators that shoot and maneuver through the water with power and grace in speedy pursuit of small fish, their main prey.

Unfortunately, their underwater lives are largely hidden from our view. We might see a loon swimming slowly on the surface, peering into the water, sometimes with its head submerged, searching for fish. Then, with a quick blip, making barely a ripple, it disappears into its element to chase and capture prey with speed and agility that we can only imagine.

Photo by Kate Persons
MOUTHFUL - A common loon tenderizes a flounder before swallowing it. Usually common loons swallow their prey underwater but will bring large or unwieldy fish to the surface to soften them. Sharp projections on the roof of the mouth and tongue angle backwards to help grip slippery fish. Besides fish, common loons eat crustaceans, snails and insect larvae. They swallow small stones to help with digestion, keeping 10 to 20 in their gizzard to grind bones and shells of crustaceans.

With a streamlined body and solid, heavy bones, these birds are built to swim and dive. Large webbed feet propel them powerfully through the water and their legs are positioned far back on their body for leverage and maneuverability. Using one foot as a rudder and the other for power, loons can flip-turn instantly, following the whims of their prey.

In order to dive quickly and swim fast, they hold their wings tight to their body, flatten their feathers to expel trapped air, and blow the air out of their lungs. Underwater, their heart rate slows to conserve oxygen.

Common loons can dive to depths of 200 feet. Usually they stay underwater for less than a minute but can stay down longer. Unless their prey is large, they consume it below the surface and have glands to excrete salt when feeding in salt water.

The loon’s extraordinary abilities underwater come at a cost when on shore. With legs so far back on their bodies, loons are clumsy on land. Common loons are barely able to walk and must push themselves along on their bellies. They come to land only to breed, nesting at the water’s edge.

Most birds have hollow bones for buoyancy in flight, but loons have compromised ease in the air for underwater prowess. Transitioning between water and air is laborious, requiring up to a quarter mile of water for common loons to gain takeoff speed, first flapping hard, then running along the water’s surface.

Once airborne, they must continuously flap fast and hard, with no soaring, to compensate for their heavy weight. During migration they fly about 60 miles per hour. They come in fast for landing and belly flop onto the water, skimming a long way on the surface in a spray of water to slow down.

Common loons can be very vocal, especially at night when pairs and neighbors fill the air with wailing, yodeling, laughing and hooting. They are most vocal on the breeding grounds when defending territories or nests or calling the family together. We miss out on much of that here, but I have heard their otherworldly wailing when common loons converse along Safety Sound.

Common loons from Alaska winter along the Pacific coast from the Aleutian Islands to south of Mexico’s Baja Peninsula. They seldom venture further than a couple miles from the coast.

Since the early 2000s, studies across southern Canada and the northern lower 48 states have found that common loons are producing fewer and fewer chicks, and abundance estimates have been trending downwards. Research points to several ways that climate change is likely impacting their productivity and survival.

Excessive runoff from more frequent extreme rainfall events has increased mercury levels and sediment in many lakes where common loons breed.

As top predators, loons are especially susceptible to mercury poisoning because mercury levels increase with each step up the food chain. Mercury poisoning affects the loon’s nervous system, causing lethargy, and impairs their ability to raise chicks. In lakes where forage fish have the highest levels of mercury, loon productivity is lowest.

The increasing flow of sediments into nesting lakes is also problematic because it clouds the water, making it harder for loons to see the fish they hunt.

Additionally, rising ocean temperatures may be changing the abundance and distribution of forage fish that common loons rely on in winter. The impact on loons is less well studied, but starvation has caused widespread die-offs of some other seabirds in the areas where loons winter. Common loons molt their wing feathers in winter, which could prevent them from moving to other areas in search of food.

If you are driving along Safety Sound, now is the time to keep an eye out for these large, handsome, black-billed loons with black-and-white checkerboard backs. And now you can imagine what is going on below the surface.