Well-known for its stirring call and elegant look, the Common Loon is a widespread breeding visitor to lakes in the northern half of North America. They depart their nesting grounds each year to overwinter along the coast, giving birdwatchers around the United States and the United Kingdom a chance to see them in winter plumage.
The Common Loon is a large waterbird with distinctly different breeding and non-breeding plumage. They are relatively dull in the winter, with slate-gray upperparts and a white chin, throat, and breast. Their bill also fades from black in the summer to pale gray in the winter.
Adults are most easily identified in the breeding season when they develop an all-black head and a broad black neckband that gleams purple and green in good light. The plumage above and below this band is smartly pin-striped in black and white. These diving birds sit low in the water, but their upperparts are visible above the surface, showing white checkering on the upper back that becomes white speckling toward the tail.
Male and female Common Loons have very similar plumages, but females tend to be smaller.
Common Loon chicks leave the nest soon after hatching and are covered in fluffy brown down before growing their juvenile plumage. Juveniles look similar to adults in non-breeding plumage, although their heads are browner.
Adult Common Loons are most similar to the Yellow-billed Loon (G. adamsii) in breeding plumage, although that species has a pale (not black) bill. Non-breeding adults also resemble smaller species like the Pacific Loon, Arctic Loon, and Red-throated Loon.
Common Loon, breeding plumage
Common Loon, non-breeding plumage
How big are Common Loons?
Common Loons are one of the largest species in their family, second only to the rarer Yellow-billed Loon. Males are generally heavier and longer than females.
Length
Most adults measure 26 to 36 inches or 66 to 91 centimeters long.
Weight
They show a wide weight range, from about 5 pounds up to nearly 17 pounds (2.2 to 7.6 kilograms).
Wingspan
Common Loons have relatively small wings, with a wingspan of just 50 to 58 inches (127 to 147 centimeters).
Common Loon stretching its wings
Calls & Sounds
What sound does a Common Loon make?
Male Common Loons produce an eerie yodeling call to mark their territory while both sexes make a low-pitched, drawn-out howl. They also make a wavering, high-pitched call in flight that sounds something like a whinnying horse.
The spooky but beautiful songs and calls of these birds have been featured in many television shows and films and will be familiar to many who have visited northern forested lakes in the spring and summer.
Common Loon, breeding plumage, calling out
Diet
What do Common Loons eat?
Common Loons eat fish (up to about 10 inches long), frogs, and invertebrates that they catch by diving below the surface. These birds are fast and agile below the water, using their webbed feet to chase down their prey.
Check out our in-depth guide to learn more about the Common Loon Diet.
What do Common Loon chicks eat?
Common Loon chicks eat small fish provided by both parents. The growing birds include invertebrates and some plant material in their diet as they learn to hunt for themselves.
Common Loon feeding on a fish
Habitat & Distribution
What is the habitat of a Common Loon?
Common Loons are diving birds that need good water visibility to pursue and catch their prey. They breed on freshwater lakes and ponds in the spring and summer but switch to marine habitats in the winter. Overwintering birds are usually seen in sheltered areas near the coast, although some forage nearly a hundred miles offshore, and others may overwinter on large freshwater bodies that remain ice-free.
What is the range of a Common Loon?
Common Loons are widespread in North America, from Alaska to Greenland in the north and to the Gulf of Mexico in the south. They also nest and overwinter around Iceland and migrate further east to overwinter in coastal areas from Finland to the United Kingdom and south to Portugal.
Where do Common Loons live?
Common Loons live in clear, fresh and saltwater habitats. They usually only leave the water to nest and migrate.
How rare are Common Loons?
Common Loons are indeed common, at least within their regular North American breeding and non-breeding range. However, these birds are migratory and have specific habitat requirements. They are relatively rare in Europe, with a small breeding population.
Common Loon taking-off from the water
Where can you see Common Loons in the US?
Common Loons nest in Alaska and the far north of the Lower 48, particularly in the Northwest, Upper Midwest, and Northeast states. They could turn up just about anywhere on migration, but winter birdwatchers are most likely to spot them in coastal waters along the West, East, and Gulf Coasts.
Common Loons breed in suitable habitats virtually throughout Canada south of the Arctic Archipelago, although they tend to avoid the prairies of the southwest. They also overwinter along the west and southeast coastlines.
Where can you see Great Northern Divers in the UK?
Great Northern Divers are winter visitors to the United Kingdom coastline. Although rare inland, birdwatchers might spot them in shallow coastal areas between October and April, particularly in the southwest of England and along Scotland’s northwest coast.
Common Loon swimming towards the camera
Lifespan & Predation
How long do Common Loons live?
Common Loons can live for over 30 years in the wild.
What are the predators of Common Loons?
Adult Common Loons are relatively safe from predators, although large birds of prey like Bald Eagles are a potential threat. Their eggs and chicks are vulnerable to many predators, such as foxes, otters, gulls, and even large fish like bass and pike.
Are Common Loons protected?
Common Loons are protected in the United States, Canada, and the United Kingdom.
Are Common Loons endangered?
Common Loons are not an endangered species. These widespread waterbirds are currently ranked as a ‘Least Concern’ species on the IUCN Red List.
Pair of breeding Common Loons
Nesting & Breeding
Where do Common Loons nest?
Common Loons nest on lakes, large ponds, and other still freshwater habitats. They build their nests right along the water’s edge so they can reach them without much walking. The nest itself is a mound-shaped structure built from twigs and other vegetation.
When do Common Loons nest?
Common Loons usually begin nesting in spring or early summer, although they may start earlier in the south of their breeding range than in the north. Their nest may take several days to build, and once laid, their eggs hatch after about four weeks.
What do Common Loon eggs look like?
Common Loons lay a single clutch of one or two spotted eggs with a brown or olive background color.
Do Common Loons mate for life?
Common Loons form long-lasting bonds, and pairs reunite year after year. They may not always mate for life, but several consecutive years is the norm. One record-setting pair from Michigan has even returned to nest together for an impressive 25 years!
Common Loon sitting on the nest by the water's edge
Common Loon at nest site with two eggs
Behavior
Are Common Loons aggressive?
Common loons are most aggressive in the breeding season when they defend nesting territories against other loons and even other species of wildfowl. These large, powerful birds will use their sharp bills to protect their young from predators, and one adult was even suspected of killing a Bald Eagle in this way!
Where do Common Loons sleep at night?
Loons usually sleep out on the water with their head turned and resting on their back. They may sleep on the nest, but only when incubating eggs.
Common Loon resting on the water
Migration
Do Common Loons migrate?
Common Loons are highly migratory birds that migrate in small groups, or independently. They usually migrate during the day, traveling at high altitudes and speeds as they fly between coastal overwintering grounds and inland nesting territories.
The Common Loon migration may be an epic journey of thousands of miles or, in some cases, a quick flight of less than 100 miles. Suitable nesting lakes are close inland from their overwintering grounds in some areas, which explains why some birds migrate short distances.
Where do Common Loons migrate to?
Most Common Loons nest on northern lakes and ponds and migrate to the coast. They are rare inland in the non-breeding season, although they may be seen on some inland waters in the American Southeast during winter.
