Red-throated Loon

Bird of the Month: Red-throated Loon

By Andy McCormick

PC: Mick Thompson (Red-throated Loon)

PC: Mick Thompson (Red-throated Loon)

Scientific Name: Gavia stellata

Length 25 in

Wingspan 36 in

Weight 3.1 lb

AOU Band code RTLO

The Red-throated Loon is named after the inverted triangular red patch on its throat in breeding plumage. However, it is winter when it is seen in Washington waters and that is when its throat and side of the face are white. At any time of year the Red-throated Loon has a distinctive appearance which provides helpful aids to identification. In flight it keeps a low profile with its small head and bill, and long, thin neck slightly lower than its back, giving it a fairly distinctive “humpbacked” look. While sitting on the water, this loon’s spine is structured so that its bill is held up at an angle. This is best seen in profile.

Despite sharing the genus Gavia, Latin for seabird, the Red-throated Loon has unique features that separate it from the other four loons world-wide that share the genus. The Red-throated is smaller and lighter than all the other loons. It breeds farther north. Unique among the loons, it takes flight more quickly and does not need a long running start at takeoff. It can also take off from land (Kaufman). It is the only loon that forages away from its nesting pond and like some alcids, it will carry fish back to its young (Barr, et al). The species name stellata refers to being adorned with stars, and refers to the white speckling on the back in non-breeding plumage (Holloway). 

The Red-throated Loon is a breeding bird of the Arctic tundra and coastal plain. It has strong site fidelity and often uses the same nest for many years. The pairs are thought to mate for life but this has not been proven. This loon prefers smaller ponds and larger lakes where it builds a nest constructed of a mass of vegetation. The nest can be on the shore or floating on the water. Typically two olive-colored eggs with dark brown spots are deposited. Incubation mostly by the female lasts about four weeks. The hatchlings take to the water in about a day and take first flight in another seven weeks.

The Red-throated makes its diet primarily of marine fish usually caught along the coast or in tidal estuaries. In winter they are almost always seen in the ocean and good looks can often be had in harsher weather when these loons tend to move closer to shore and forage in shallow water. 

The world population of Red-throated Loons may be estimated at around 100,000 individuals (Barr, et al). The western Alaskan population has dropped by about 50% between 1977 and 1993 (Alderfer, Barr et al). The cause of the decline is not known, but we have some theories. The Pacific Loon population is larger than that of the Red-throated and the two species compete for space in breeding areas. Oil spills are a threat to Red-throated Loons and large numbers worldwide are caught in fishing nets. Acidification in ponds is another possible cause of decline.