Common Loon

The Common Loon, or Great Northern Diver (Gavia immer), is a large aquatic bird known for its striking plumage and haunting calls. Breeding adults boast a black head and neck with a lustrous sheen that can appear greenish, purplish, or bluish, depending on the light. Their upperparts are blackish-grey, while the underparts are predominantly white, with some black on the undertail coverts and vent. In contrast, non-breeding adults don a brownish plumage with a dark neck and head marked with grey-brown. Both sexes are similar in appearance, though males are notably heavier than females.

Identification Tips

The Common Loon is identified by its heavy, tapered bill, red eyes, and a distinctive black ring around the neck during breeding season. The checkered black-and-white mantle is another characteristic feature. In flight, the loon's head is slightly lower than its body, with feet trailing behind. Juveniles have a dark, brownish-grey nape and a grey to black head, neck, and upperparts, with a white throat and underparts.

Habitat

During the breeding season, Common Loons inhabit lakes and waterways in Canada, the northern United States, and parts of Greenland and Iceland. They prefer large lakes with clear waters, abundant fish, and islands or coves for protection.

Distribution

Common Loons breed across Canada, the northern United States, Greenland, and Iceland, with small numbers in Svalbard and Arctic Eurasia. In winter, they migrate to coastal regions of the US, as far south as Mexico, and the Atlantic coast of Europe.

Behaviour

Loons are powerful swimmers, using their webbed feet to propel themselves underwater in pursuit of prey. They are awkward on land due to their leg placement towards the body's rear. Loons are territorial, especially during breeding season, and may exhibit aggressive behavior towards intruders.

Song & Calls

The Common Loon is known for its eerie calls, including the tremolo, yodel, wail, and hoot. Each call serves a specific purpose, such as signaling distress, establishing territory, or communicating with family members.

Breeding

Loons are monogamous and may breed with the same partner for several years. They build large nests along lake shores, laying one or two olive-brown eggs. Both parents incubate the eggs and care for the chicks, which fledge in about 70 to 77 days.

Similar Species

The Common Loon can be confused with the similar Yellow-billed Loon but can be distinguished by its black bill and the pattern of white markings on the neck during breeding season.

Diet and Feeding

Common Loons primarily feed on fish, supplemented by crustaceans, insect larvae, molluscs, and occasionally aquatic plants. They are adept at catching prey underwater, often swallowing it whole.

Conservation Status

The Common Loon is classified as Least Concern by the IUCN. However, it faces threats from habitat loss and pollution, including mercury and lead poisoning. Conservation efforts include habitat protection and reducing environmental contaminants.