Overview
The Red-throated Diver (Gavia stellata), known in North America as the Red-throated Loon, is the smallest, lightest, and most widely distributed member of the ancient loon family Gaviidae. Possessing an extensive circumpolar breeding range across the high Arctic tundra and boreal peatlands, it is distinguished from all other divers by its unique ability to launch directly into flight from small, shallow tarns without requiring a long water take-off run.
In full breeding dress, Gavia stellata is a bird of sublime northern elegance, adorned with an ash-grey head, fine vertical zebra-striping down the back of the neck, and a luminous, wine-red triangular throat patch. Its rapid, agile flight and goose-like honking flight calls are iconic heralds of spring across the Arctic, where it performs vital ecological duties as an agile coastal pursuit predator.
AT A GLANCE
- Common Name: Red-throated Diver
- Scientific Name: Gavia stellata
- Category: Birds
- Subcategory: Loons
- Size: 53 to 69 cm (21 to 27 in) length; 106 to 116 cm (42 to 46 in) wingspan
- Weight: 1.2 to 2.0 kg (2.6 to 4.4 lb)
- Lifespan: 15 to 20 years in the wild; maximum recorded over 23 years
- Diet: Piscivorous: marine and freshwater small fish (sand eels, sprats, cod, sticklebacks, sculpins), crustaceans, and marine worms
- Habitat: Small, shallow tundra tarns and boggy pools during the summer breeding season; inshore marine coastal waters, bays, and estuaries in winter.
- Range: Circumpolar Arctic and subarctic breeding range across northern North America, Greenland, Iceland, northern Europe, and Siberia; winters along marine coasts of the Atlantic and Pacific.
- Conservation Status: Least Concern (IUCN Red List)
Biology and Physical Characteristics
Gavia stellata is the most slender diver, with a streamlined, torpedo-shaped body, short neck, and slightly uptilted dagger-like bill that gives it an inquisitive, elevated head posture. In summer, its plumage displays a smooth, unmarked greyish-brown mantle, a soft dove-grey head, and vertical black-and-white pin-striping running down the nape. Its hallmark field mark is an elongated, iridescent triangular patch of rich chestnut-red located squarely on the lower throat.
Its skeleton, like all loons, features dense, solid bones that reduce buoyancy for effortless underwater pursuit. However, its wings are relatively longer and lighter than those of its congeners, giving it a lower wing-loading that permits instantaneous vertical take-offs from tiny bodies of water where larger loons would remain hopelessly grounded.
Behavior and Ecology
Unlike larger loons that hunt within their vast breeding lakes, the red-throated diver breeds almost exclusively on tiny, fishless tundra pools and bog tarns, often only a few dozen yards across. To feed their chicks, the adult pair commutes continuously back and forth to the nearby ocean or large rivers, carrying small marine fish such as sandeels and sprats crosswise in their bills over distances of several miles.
Their courtship displays are among the most spectacular in the avian world: mated pairs perform synchronized swimming ballets, raising their breasts clear out of the water in a ‘penguin dance’, churning the surface into foam with their webbed feet, and duetting in loud, wailing, yodeling harmonies. The female lays two olive-brown spotted eggs in a scrape at the water’s edge, incubating them for about 27 days.
Conservation and Human Impact
The Red-throated Diver is classified as Least Concern on the IUCN Red List due to its enormous circumpolar breeding population across Canada, Alaska, Scandinavia, and Russia. It enjoys legal protection under the Migratory Bird Treaty Act and the European Union Birds Directive.
Nevertheless, localized populations in northwestern Europe face growing challenges from the rapid expansion of offshore wind farms, which can cause displacement from critical marine foraging grounds and bird collision mortality. Marine oil pollution, plastic entanglement, and heavy metal bioaccumulation in coastal wintering grounds remain persistent threats that require continued monitoring.
Interesting Factoid
Unlike all other loons which need a running start of up to 200 yards across the water to become airborne, the red-throated diver can take off directly into flight from tiny tundra puddles just a few yards wide.