Fr: Plongeon à bec blanc
Ang: Yellow-billed Loon – White-billed Diver
All: Gelbschnabeltauche
Esp: Colimbo de Adams
Ita: Strolaga beccogiallo
Nd: Geelsnavelduiker
Sd: Vitnäbbad islom
Photographers:
John Anderson
John Anderson Photo Galleries
Didier Buysse
Vision d’Oiseaux
Tom Grey
Tom Grey's Bird Pictures
Alan & Ann Tate
AA Bird Photography
Text by Nicole Bouglouan
Sources :
HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105
BirdLife International (BirdLife International)
Bird Web (Seattle Audubon Society)
Animal Diversity Web (University of Michigan Museum of Zoology)
What Bird-The ultimate Bird Guide (Mitchell Waite)
Wikipedia, the free encyclopaedia
BIOKIDS - Kids' Inquiry of Diverse Species
Page Family Gaviidae
Summary cards
Yellow-billed Loon or White-billed Diver
Gavia adamsii
Gaviiformes Order – Gaviidae family
INTRODUCTION:
The Yellow-billed Loon or White-billed Diver is the largest species of the family Gaviidae. The body is designed for life in the water, and its morphology with legs attached at the far end of the body is more adapted to swimming than walking. It only takes off from water surface.
It lives in cold regions in Pacific and Arctic Oceans, usually along the coastlines.
This monotypic species was first described by the English zoologist George Robert Gray in 1859.
The adult in non-breeding plumage has dark grey-brown upperparts with darker squares on scapulars and white-spotted wing-coverts. On the underparts, central breast and belly are white.
Head and neck are grey-brown with paler neck sides. Lower face and eye area are creamy-white. Ear-coverts are brownish. Chin, throat and foreneck are whitish. The lower neck sides show brownish tiny speckles forming a diffuse, broken collar. The bill becomes pale blue-grey.
Both sexes are similar.
The juvenile 1st summer resembles non-breeding adult but slightly paler, with broad pale fringes to dorsal feathers. Scapulars show scaly appearance. Head and neck pattern is paler than in adults, with weak partial collar on the lower neck.
The second winter is similar to non-breeding adult but without white spots on wing-coverts.
The second summer is a mix of adult and juvenile plumages.
RANGE:
The Yellow-billed Loon or White-billed Diver is an arctic species. It breeds primarily along the coasts of the Arctic Ocean and on inshore islands. It winters in sheltered waters in the northern Pacific Ocean and the NW coast of Norway.
There are records of breeding birds in Russia, Canada and USA. The winter range may extend off the coasts of Japan. This species is vagrant in several countries.
HABITAT:
The Yellow-billed Loon or White-billed Diver breeds on freshwater lakes, ponds and pools, ponds of tundra and in estuaries. It usually avoids forested areas. It winters on inshore coastal waters in more temperate areas.
CALLS AND SONGS: SOUNDS BY XENO-CANTO
The Yellow-billed Loon or White-billed Diver utters the typical yodel call, a very loud and far-carrying call. This haunting sound is used to proclaim the territory. This is a long call similar to a low-pitched whistle interspersed with clear notes.
The alarm call is a series of strident laughing notes. The contact call is a low-pitched moaning sound used between parents and juveniles, and produced by the male during the copulation “ooo” or “aaa”.
BEHAVIOUR IN THE WILD:
The Yellow-billed Loon or White-billed Diver feeds on small to medium-sized fish, and crustaceans such as isopods and shrimps. It may sometimes eat snails, slugs and spiders.
Most preys are taken near the surface, but this bird can dive at depth of 2/10 metres or more. It pursues the prey underwater. The fish is usually swallowed before the bird surfaces, or carried out of water if too big. It feeds by day and locates the preys by sight.
It uses its webbed feet to propel itself underwater, but the wings can be occasionally extended for better manoeuvring.
The Yellow-billed Loon or White-billed Diver is monogamous and the pairs have long-term pair-bonds, usually for life. They often use the same territory during several following years.
The established pairs nest after a minimum of displays. However, the new pairs have simple courtship displays including several synchronized movements such as “bill-dipping”, “splash-diving” and “rushing” underwater. These displays occur usually prior to copulation which takes place onshore, on dry land, and is frequently repeated.
The courtship displays of this species can be used as threat displays too. The Yellow-billed Loon or White-billed Diver is highly territorial and defends strongly its territory against other adults and any intruder. It has a wide range of aggressive postures. The neck is raised in order to display throat and neck patterns. Other forms of territorial displays are performed often accompanied by calls.
Fights can be intense and violent while the birds use bill and wings, and may result in the death of one, or both, of the birds.
The Yellow-billed Loon or White-billed Diver is migratory and moves southwards towards the sea after the breeding season.
It is a good flier and can travel long distances, flying over land or water, often high in the sky. The take-off needs a long run along the surface, and the landing also takes place on water. It flies swiftly, with outstretched neck. On the other hand, divers progress with great difficulty on land, due to the legs attached at the far end of the body.
REPRODUCTION OF THIS SPECIES:
The breeding season usually starts in early June, but depends on spring thaw. This species is solitary nester.
The nest is a pile of plant matter forming a depression lined with grasses and placed on the ground near water. The nest-site is close to lakes and coastal ponds and in tundra, with good visibility over the surroundings.
The female lays 2 olive to brown eggs with darker spots. Both adults incubate during 27-30 days. The chicks leave the nest one or two days after hatching, and can be seen sometimes riding on adults’ backs.
Both parents feed and tend them, and defend them strongly. The young fledge about 9 weeks after hatching.
PROTECTION / THREATS / STATUS:
The Yellow-billed Loon or White-billed Diver is vulnerable to oil spills in both breeding and wintering ranges. They are threatened by drowning in fishing nets.
Divers have low reproductive rate and need very specific breeding habitat requirements.
The population is estimated at 11,000/21,000 mature individuals and is decreasing. The Yellow-billed Loon or White-billed Diver is currently classified as Near Threatened.
DESCRIPTION OF THE BIRD:
Biometrics:
Length: 76-92 cm
Wingspan: 137-152 cm
Weight: 4000-6400 g
The adult in breeding plumage is black and white. Head and neck are black with green to purplish iridescence. There are two striped black-and-white neck collars. The upper one is narrow and short, visible on the upper throat, whereas the second partial collar is broader, extending from the neck sides to the hindneck.
On the upperparts, we can see a checked black-and-white pattern with spotted and speckled back. The upperwing is black with spotted white coverts, except the primary coverts. The tail is black. Lower back and uppertail-coverts are mostly blackish and unspotted.
The underparts are white except some black markings on the undertail-coverts. The underwing shows white wing-coverts. The axillaries have long black shaft-streaks.
The dagger-shaped bill is pale yellowish or ivory-coloured. The eyes are reddish-brown to deep red or red. Legs and webbed feet are greyish-brown, but pale grey on the inner half.
