With a distinct call that many birders associate with summer and easily recognized by its black-and-white checkerboard plumage, the common loon is a relatively delicate species that requires pristine nesting habitat and exacting environmental conditions to thrive. Because of this, these members of the Gaviidae bird family can be one of the earliest indicators of environmental health. Discovering more common loon facts can help ever birder better appreciate what makes these birds even more extraordinary!
- Scientific Name: Gavia immer
- Common Name: Common Loon, Great Northern Loon, Great Northern Diver
- Lifespan: 25-30 years
- Size: 30-35 inches long
- Weight: 10-14 pounds
- Wingspan: 55 inches
- Conservation Status: Least concern
Common Loon Identification
These birds are relatively easy to identify with their distinctive, streamlined shape and long, thick, dagger-like black bills. Genders are similar with a black head and neck that can show an iridescent greenish or green-blue sheen in good light and a wedge-shaped collar of vertical black and white stripes. The breast and abdomen are plain white, and the back is checkered black and white with finer markings on the flanks and rear. The eyes are red, but can be difficult to see in the dark face. In winter, the plumage is brownish and mottled with more white on the face and neck.
Juvenile common loons have less distinct markings and may appear duller or less refined, and they lack the distinct collar. Their bills are also generally paler, and they show short white arcs around their dark eyes. Juvenile plumage most closely resembles non-breeding adults.
The mournful call of the common loon has a yodeling, warbling quality that starts lower in tone but has a rising pitch through the call. These calls carry great distances across water and have become common summer sounds in the birds' breeding range.
Common Loon vs. Yellow-Billed Loon
The common loon and yellow-billed loon look very similar. In winter, they can be challenging to tell apart, except the common loon is much more widespread and more likely to be seen in southern coastal areas. When the birds are in their breeding plumage, the common loon has less white on its back than its yellow-billed counterparts, and its collar is more severely wedge-shaped, whereas the yellow-billed loon’s collar is more of a bulge or ellipse. Of course, the contrasting colors of these birds’ bills is a distinct field mark to separate them in any season.
Common Loon Habitat and Distribution
Common loons can be common sights in both the treeless tundra and boreal forest regions of Canada where large, deep, open bodies of water are found. Their preferred habitat must have rich fishing resources available, and shorelines with marshy grasses are typically favored. Outside of the breeding season, they are often found in ocean coastal habitats, though they tend to stay somewhat offshore or in deep inlet areas.
The common loon’s summer breeding range extends from Alaska to the edge of the continental United States. In winter, they migrate to both the Atlantic and Pacific coasts as far south as Florida, the Gulf Coast, and Mexico, though they can also be found on large inland lakes. These birds inhabit similar habitats in northwestern Europe, particularly Iceland, Scandinavia, and Great Britain.
These birds are slow and awkward on land and may seem unable to walk at all, but on the water they are powerful swimmers that can dive up to 200 feet deep for a full minute while they hunt. They sleep on the water and need long stretches of open water to run across to gain enough momentum to take flight. When at rest on the water’s surface, they tend to ride low, giving an exceptionally low profile that accentuates their streamlined bodies and larger heads.
Diet and Feeding
Common loons are piscivorous birds, and fish make up approximately 80 percent of their diet. They will also eat a range of invertebrates, crustaceans, mollusks, and aquatic insects as well. To feed, they dive below the surface and chase after their prey, swallowing whatever they catch headfirst. They are very agile swimmers, and use their powerful legs to follow their prey easily. Common loons are visual hunters, however, so it is essential that their waterways be clear and clean for easy foraging.
Younger loons eat mostly minnows and other small prey, but adults will catch and consume fish up to 10 inches in length. The exact fish common loons favor depends on what species are most available in their habitats, but they have been noted as eating a wide range of both saltwater and freshwater fish, including bass, pike, burbot, shad, crappies, smelt, trout, herring, haddock, and perch.
Common loons are monogamous birds. The nest is built on a small island or along the shoreline of a protected lake or bay, often in a reedy patch that offers some concealment. Some nests may even be floating in boggy areas. The nest structure is a bulky, low mound of stems, grasses, and twigs, and both members of a mated pair work together to build it. If a pair of loons successfully raises chicks, they may reuse the same nest the following breeding season.
Eggs and Young
These birds lay 1-4 oval-shaped, dull olive-green eggs per brood. A mated pair shares incubation duties for 26-30 days, and after the eggs hatch, the chicks leave the nest right away and ride on their parents' backs for swimming and diving. Both parents will care for the young birds for 70-80 days, and only a single brood is raised each breeding season.
Common Loon Conservation
While these birds are not considered threatened or endangered, they are sensitive to environmental changes and can be at grave risk from water pollution and soil erosion that will cloud waterways and make it more difficult for them to forage effectively. Acid rain and other contaminants that can alter the ecology of large lakes and waterways is also damaging to common loons, and these birds can be subject to lead poisoning from fishing sinkers.
Ultimately, protecting northern waterways and lakes will help protect common loons. Steps to mitigate flooding and severe water fluctuations are essential, and a healthy fish population must be preserved to provide adequate food sources for these birds.
Tips for Backyard Birders
These are not backyard birds but may be present at northern lakeside camping areas or where homes abut a suitable lakeshore. Protecting the shoreline and minimizing local pollution and erosion can help attract common loons. In some areas, these birds have also used artificial nesting platforms that float near suitable shorelines.
How to Find This Bird
Common loons can be difficult to see in the wild because of their shy, skittish nature. They may abandon their nests if spooked and because of this, many common loon nesting areas are protected. Birders looking to see common loons should have a powerful spotting scope or high-magnification binoculars available and watch for these birds floating on deep water some distance from shore.
Common Loons in Culture
The common loon has been the official state bird of Minnesota since 1961, and it is also the official provincial bird of Ontario, Canada. Because of its distinctiveness, the common loon is also a popular mascot for schools and businesses within its range, as well as the symbol of the Minnesota United FC professional soccer team. In northern areas, many summer festivals celebrate common loons.
Explore More Species in This Family
While the Gaviidae bird family only includes the five loon species of the world, there are other birds that are similar. Birders interested in learning about related species should take an interest in:
Don’t miss any of our other wild bird profiles to learn plenty of facts about all your favorite bird species!