Common Loon

Identification

The common loon, also known as the great northern diver in Eurasia, is a large waterfowl ranging from 66 to 91 centimetres in length with a wingspan of 127 to 147 centimetres. Breeding adults are unmistakable, featuring a broad black head and neck with a greenish, purplish, or bluish sheen, blackish or blackish-grey upperparts, and pure white underparts. They have a distinctive black bill, sometimes with a pale tip, and striking red eyes. A characteristic black ring encircles the neck. Non-breeding adults are considerably duller, appearing brownish with dark grey-brown markings on the head and neck, and an unclear pattern of squares on the shoulders. The sexes look alike, though males are significantly heavier than females, with males averaging up to nearly 27 percent more massive than females in some populations.

Range & Habitat

During breeding season, common loons inhabit lakes and other waterways across Canada, the northern United States (including Alaska), and southern parts of Greenland and Iceland, with small numbers breeding on Svalbard and sporadically elsewhere in Arctic Eurasia. In winter, they are found on both coasts of North America as far north as Newfoundland and Alaska, and as far south as Mexico, as well as on the Atlantic coast of Europe. Loons breed on lakes with vegetated shores where they can build their nesting mounds.

Behaviour & Diet

Common loons are monogamous birds, with paired males and females often defending a territory together and potentially breeding for a decade or more. Both members of a pair construct large nests from dead marsh grasses and other plant materials, formed into mounds along vegetated lake shores. They typically raise a single brood annually from a clutch of one or two olive-brown oval eggs with dark brown spots, incubated for about 28 days by both parents. Chicks fledge in 70 to 77 days and are capable of diving underwater within just a few days of hatching; they fly to their wintering areas before autumn ice forms.

Loons feed on a variety of animal prey including fish, crustaceans, insect larvae, and molluscs, occasionally supplemented with aquatic plant life. They typically swallow prey underwater where it is caught, though larger items are sometimes brought to the surface first.

Best Time & Places to See It

Common loons are best observed during the breeding season on northern lakes in Canada and the northern United States. Winter sightings are possible on both Atlantic and Pacific coasts of North America, as well as on the Atlantic coast of Europe. The species is assessed as of least concern and is protected under the Agreement on the Conservation of African-Eurasian Migratory Waterbirds, making it a reliable subject for nature travellers visiting northern waterways.

Photography Tips

Photographers should note that breeding adults in their striking black and white plumage are far more visually dramatic than non-breeding birds, making the breeding season ideal for compelling images. The loons' diving behaviour offers excellent opportunities for action photography, and their distinctive red eyes and black-and-white patterns are most visible during close encounters on calm water. The characteristic black neck ring is a key field mark worth capturing. Early morning light on northern lakes will best showcase the iridescent sheen on their head and neck.