What Do Loons Eat?

Loons are probably among the most beautiful aquatic birds, thanks to their unique plumage colors and patterns! Did you know that some loon species are considered top predators in their habitats or that their fish diet may make them vulnerable to pollutants? Keep reading to learn more interesting facts about their feeding habits!

What Are Loons?

Loons are aquatic birds living in North America and northern Eurasia. These birds are part of the Gavia genus in the Gaviidae family. They resemble ducks and geese in their swimming techniques. Loons are a bit larger than ducks and smaller than geese. Like the two, loons have toes connected by webbing.

Loons are officially classified into five major species:

• Gavia stellata, commonly called red-throated loon, lives in the Northern hemisphere in coastal areas in winter and inland in summer.
• Gavia arctica, commonly called black-throated loon, lives in Northern Europe and Asia in coastal areas in winter and breeding on land.
• Gavia pacifica, commonly called Pacific loon, lives in northern Canada and eastern Siberia, spending winters along North America’s Pacific coast.
• Gavia immer, commonly called Common loon, lives on U.S. coasts and Europe’s Atlantic coast.
• Gavia adamsii, commonly called Yellow-billed loon, lives in Russia, the United States, Canada, Mexico, and Spain.

Male and female loons look roughly the same – most species have a black-and-white plumage in the summer, while others may have gray heads and necks; all species have white bellies. During winter, their plumage turns dark gray above, with light mottling on the wings, and they have white chins, undersides, and throats. In terms of size, males are a bit larger, but this isn’t easily distinguishable unless males and females are seen together. 

These aquatic birds are excellent swimmers. They can fly well, too, having recorded daily flights of up to 669.8 miles. On the other hand, they can’t walk long distances on land. Loons may live up to 30 years.

What Do Loons Eat?

Loons are fish-eating experts, as their diets primarily consist of fish. Sometimes they may eat crayfish, snails, frogs, salamanders, and leeches. Some loon species eat vegetation too, so outlining a single diet for all loon species would be impossible, as they can be either omnivorous or carnivorous.

Besides their main food, loons include in their “diet” pebbles from the bottoms of lakes. Like other animals, they swallow it to make digestion easier. Since they eat prey with exoskeletons and bones, their gizzard needs help crushing these hard parts, and pebbles are great at doing this. Moreover, they can also clean the stomach.

Since they use their excellent sight for foraging, they prefer living in clear lakes. Loons have a pointy bill to stab their prey.

What Do Red-Throated Loons Eat?

Like other loon species, red-throated loons primarily eat fish but supplement their diet with crustaceans, aquatic invertebrates, mollusks, frogs, insects, and sometimes plants. Unfortunately, the fish in their diet makes their immune system more vulnerable to organic pollutants and heavy metals.

What Do Black-Throated Loons Eat?

Black-throated loons are considered top predators in some subarctic lakes’ pelagic zones. They prefer fish above all but may eat insects, crustaceans, mollusks, and vegetation. These birds look for food either alone or in pairs.

What Do Common Loons Eat?

Common loons exhibit the same feeding habits as other loon species, as 80% of their diet consists of fish. These include minnows, gizzards, suckers, rock bass, shad, alewife, whitefish, sauger, brown bullhead, burbot, bluegill, walleye, white crappie, and killifish. They can eat fish as long as 10 inches long.

In freshwater habitats, they primarily rely on pike, sunfish, trout, and perch. In saltwater ecosystems, common loons eat rockfish, flounder, herring, and haddock. If they can’t find any fish in the surroundings, they’ll turn to crustaceans, snails, frogs, mollusks, and vegetation. In terms of plant matter, they’ll feed on willow shoots, pondweed, algae, seeds, and roots.

What Do Pacific and Yellow-Billed Loons Eat?

Like their relatives, Pacific loons and yellow-billed loons primarily eat fish and sometimes crustaceans, annelids, and mollusks. 

A List of Foods Loons Eat:

Here’s a list of foods loons eat:

• Fish 
• Crustaceans
• Annelids
• Mollusks
• Crayfish
• Salamanders
• Snails
• Frogs
• Leeches
• Vegetation 

What Do Loons Feed Their Young Ones?

Red-throated loons, for example, feed their babies with aquatic insects and small crustaceans for the first days of their lives. After 3 – 4 days, they provide the young with fish small enough for them to swallow whole. When they’re four weeks old, young red-throated loons switch to adult diets.

Black-throated loons feed away from their nests but forage food for their babies nearby the nest. For the first eight days, black-throated loon babies are fed with three-spined sticklebacks and common minnows – that is, if their parents can find it. If they aren’t abundant, babies will eat small invertebrates.

Then, they switch to trouts measuring 3.9 inches long alongside invertebrates and salmonids measuring 3.9 – 9.4 inches long.

Black-throated loons feed their young with only one prey item at a time, usually until they are about 70 days old. However, black-throated young loons are capable of capturing their food as early as 36 days after hatching.

Young common loons eat small minnows, insects, and vegetation. 

Where Do Loons Go in the Winter?

Red-throated loons inhabit the Arctic regions of North America and northern Eurasia. During winter, they go to northern coastal waters.

Black-throated loons usually live in Northern Europe and Asia. They winter on the northeastern Atlantic coasts and eastern and western Pacific coasts.

Common loons generally inhabit U.S. coasts and Europe’s Atlantic coasts. In North America, common loons spend their winters along the northeastern Pacific and northern Atlantic coasts. Many Iceland common loons do not migrate, spending their summers and winters there.

Pacific loons winter primarily on North America’s Pacific coast. However, many loons may spend their winters on large lakes in North America, Asia, and Europe.

Yellow-billed loons winter on northern Pacific coasts and Norway’s northwestern coast. Some yellow-billed loons winter on Japan’s coast.

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The photo featured at the top of this post is © Rejean Bedard/Shutterstock.com