Red-throated Loon: where and when to see them

Known in Britain as the red-throated diver, this slender waterbird breeds on small northern freshwater pools and often feeds at sea. Its breeding plumage combines a grey head, finely striped hindneck and deep reddish throat patch. Winter birds become much paler and less distinctive. Scotland supports important breeding populations, especially in the north and west, but their quiet nesting lochans are sensitive places where distant observation is essential and close approach is inappropriate.

Size

Length 53–69 cm

Weight

1.2–2.5 kg

Lifespan

Not reliably established

Status

Least Concern

Pairs defend nesting pools and communicate with far-carrying calls and coordinated displays. Unlike larger loons, red-throated loons can take flight from relatively small bodies of water, allowing them to use modest breeding ponds. Adults frequently commute to coastal feeding areas and bring fish back to their chicks. Nests sit close to the water's edge, making eggs vulnerable to disturbance and changing water levels. Outside breeding, birds often occur singly or in loose coastal gatherings. Courtship displays involve synchronized swimming, mutual preening, and various calls to solidify pair bonds. Chicks are semi-precocial, able to swim shortly after hatching but dependent on parental feeding and protection for several weeks. Unlike many seabirds, they do not nest in colonies, preferring solitary territories for breeding success.

• It is the smallest living loon species.
• Its legs sit far back on the body, making walking difficult.
• Parents often carry fish from the sea to freshwater-reared chicks.
• It can use smaller breeding pools than the larger loon species.

May through August offers breeding-plumage views in northern and western Scotland, preferably at coastal feeding areas rather than nests. Autumn and winter can also suit seawatching in sheltered bays. Weather, visibility and local movements matter more than a guaranteed seasonal concentration. Prime viewing from cruise ship decks can occur during migration periods, especially along coastal routes in spring and autumn. During the breeding season, quiet observation from land-based tours at designated viewpoints is best to avoid disturbance. Local birdwatching guides can advise on specific sheltered bays and estuaries known for wintering populations.

Breeding habitat includes small moorland lochans, peatland pools and shallow northern lakes with low-disturbance margins. Feeding waters may be coastal bays, sounds or larger freshwater bodies. In winter, sheltered and moderately exposed coastal seas become more important than inland nesting sites. Red-throated loons are the most widespread loon species, with a circumpolar breeding range extending across Arctic and subarctic regions of Eurasia and North America. In winter, they migrate south to coastal waters of temperate zones, favoring areas with a rich food supply. While nesting, they prefer oligotrophic waters, meaning those with low nutrient levels, often surrounded by open tundra or heathland.

Small fishes dominate the diet, captured during submerged pursuit. Adults may travel between nesting pools and richer coastal feeding grounds to obtain suitable prey for chicks. Crustaceans and other aquatic animals are occasionally eaten, but fish remain the principal food source. Prey capture occurs quickly underwater, with the loon typically surfacing a short distance away from where it dove. Parental care involves both adults bringing food to the chicks, with an increasing proportion of larger fish as the young grow. Occasionally, they will also consume insects and amphipods when fish are scarce or during early chick development.

Common name

Red-throated Loon

Scientific name

Gavia stellata

Animal group

Birds

Size

Length 53–69 cm

Weight

1.2–2.5 kg

Lifespan

Not reliably established

Status

Least Concern

Identification

Its slender, slightly upturned bill and small build distinguish it from black-throated and great northern loons, with a red throat patch visible in breeding plumage. Beyond the red throat, breeding adults exhibit a pale grey head and neck, a dark back, and white underparts, creating a striking contrast. Non-breeding adults and juveniles appear greyer overall, lacking the distinctive red patch and showing fine white spotting on the back, resembling a miniature Great Northern Loon. Its distinctive, cat-like wailing call is also a key identification feature, often heard before the bird is seen.