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Gaviidae - Divers or Loons

Loon
Red-throated Diver Gavia stellata ©Will Price Website

The Gaviidae commonly called divers (UK/Ireland) or loons (North America) are a group of aquatic birds found in many parts of North America and northern Eurasia. All living species of are members of the genus Gavia, family Gaviidae and order Gaviiformes.

Generally all the species are the size of a large duck or small goose, which they resemble superficially when swimming. Like ducks and geese but unlike coots (which are Rallidae) and grebes (Podicipedidae), their toes are connected by webbing. They may be confused with cormorants (Phalacrocoracidae), which are relatives of divers and like them are heavy set birds whose bellies – unlike those of ducks and geese – are submerged when swimming. Flying divers resemble a plump goose with a seagull's wings, relatively small in proportion to the bulky body. The bird holds its head pointing slightly upwards during swimming, but less so than cormorants do. In flight the head droops more than in similar aquatic birds.

Males and females have identical plumage. All species are largely patterned black-and-white in summer, with grey on the head and neck in some species, and one has a red-throat patch when in breeding plumage. All have a white belly. This resembles many sea-ducks (Merginae) – notably the smaller goldeneyes (Bucephala) – but is distinct from most cormorants which rarely have white feathers, and if so usually as large rounded patches rather than delicate patterns. All species of divers have a spear-shaped bill.

In winter plumage is dark grey above, with some indistinct lighter mottling on the wings, and a white chin, throat and underside. The species can then be distinguished by certain features, such as size and colour of head, neck, back and bill, but often reliable identification of wintering divers is difficult even for experts – particularly as the smaller immature birds look similar to winter-plumage adults, making size an unreliable means of identification.

Gaviiformes are among the few groups of birds in which the young moult into a second coat of down feathers after shedding the first one, rather than growing juvenile feathers with downy tips that wear off as is typical in many birds. This trait is also found in tubenoses (Procellariiformes) and penguins (Sphenisciformes), both relatives of divers.

They are excellent swimmers, using their feet to propel themselves above and under water while their wings provide assistance. Because their feet are far back on the body, loons are poorly adapted to moving on land, and usually avoid going onto land, except when nesting. They are all decent fliers, though the larger species have some difficulty taking off and thus must swim into the wind to pick up enough velocity to become airborne.

They find their prey by sight. They eat mainly fish, supplemented with amphibians, crustaceans and similar mid-sized aquatic fauna. Specifically, they have been noted to feed on crayfish, frogs, snails, salamanders and leeches. They prefer clear lakes because they can more easily see their prey through the water. They use their pointed bill to stab or grasp prey. They eat vertebrate prey headfirst to facilitate swallowing, and swallow all their prey whole. To help digestion, they swallow small pebbles from the bottoms of lakes. While they spend most of their time at sea, they nest during the summer on freshwater lakes or ponds. Smaller bodies of water will usually only have one pair. Larger lakes may have more than one pair, with each pair occupying a bay or section of the lake. Red-throated divers, however, may nest colonially, several pairs close together, in small Arctic tarns and feed at sea or in larger lakes, ferrying the food in for the young.

This family consists of just five species, which are:

Red-throated Diver Gavia stellata
Black-throated Diver Gavia arctica
Pacific Loon Gavia pacifica
Great Northern Diver Gavia immer
Yellow-billed Diver Gavia Adamsii

Family Links

Divers or Loons Gaviidae

Family Account

Family account

Divers or Loons Gaviidae

Family Account

Family account

Divers or Loons Gaviidae

Webpage

IBC familky account

Divers or Loons Gaviidae

HBW Family Account

HBW Family account

Divers or Loons Gaviidae

Family Account

Family account

Species Links

Black-throated Diver/Loon Gavia arctica

RSPB Species Account

Species account

Great Northern Diver or Common Loon Gavia immer

Species Account

The great northern loon (Gavia immer), is a large member of the loon, or diver, family of birds. The species is known as the common loon in North America and the great northern diver in Eurasia; its current name is a compromise proposed by the International Ornithological Committee.

Red-throated Diver/Loon Gavia stellata

RSPB Species Account

Species account

Great Northern Diver or Common Loon Gavia immer

BirdLife Species Account

BirdLife species status

Great Northern Diver or Common Loon Gavia immer

Species Account

Sound archive and distribution map.

Great Northern Diver or Common Loon Gavia immer

HBW Species Account

HBW species account

Great Northern Diver or Common Loon Gavia immer

IBC Species Account

IBC species account

Black-throated Diver/Loon Gavia arctica

Species Account

The black-throated loon (Gavia arctica) is a migratory aquatic bird found in the northern hemisphere. The species is known as an Arctic loon in North America and the black-throated diver in Eurasia. Its current name is a compromise proposed by the International Ornithological Committee

Black-throated Diver/Loon Gavia arctica

Species Account

Sound archive and distribution map.

Black-throated Diver/Loon Gavia arctica

IBC Species Account

IBC species account

Black-throated Diver/Loon Gavia arctica

HBW Species Account

HBW species account

Pacific Loon or Diver Gavia pacifica

BirdLife Species Account

BirdLife species profile

Pacific Loon or Diver Gavia pacifica

Species Account

Pacific Loon or Diver Gavia pacifica

Species Account

Sound archive and distribution map.

Pacific Loon or Diver Gavia pacifica

HBW Species Account

HBW species account

Pacific Loon or Diver Gavia pacifica

Cornell Species Account

The Pacific Loon is perhaps the most abundant loon in North America.

Red-throated Diver or Loon Gavia stellata

Webpage

BirdLife species profile

Red-throated Diver/Loon Gavia stellata

Species Account

Red-throated Diver/Loon Gavia stellata

Species Account

Sound archive and distribution map.

Red-throated Diver/Loon Gavia stellata

IBC Species Account

IBC species account

Red-throated Diver/Loon Gavia stellata

HBW Species Account

HBW species account

White-billed Diver or Loon Gavia adamsii

IUCN Species Status

White-billed Diver/Loon Gavia adamsii

Species Account

White-billed Diver/Loon Gavia adamsii

BirdLife Species Account

BirdLife status and profile

White-billed Diver or Loon Gavia adamsii

Webpage

HBW species account

White-billed Diver/Loon Gavia adamsii

Species Account

Sound archive and distribution map.

White-billed Diver/Loon Gavia adamsii

IBC Species Account

IBC species account

Red-throated Diver/Loon Gavia stellata

Cornell Species Account

The smallest of the loons, the Red-throated Loon breeds at high latitudes in North America and Eurasia.

Number of Species

Number of bird species: 5

Useful Reading

Seabirds

by Peter Harrison - Helm 1985

ISBN: 071363510X

Buy this book from NHBS.com

Flight Identification of European Seabirds

by Anders Blomdahl, Bertil Breife & Niklas Holmstrom from Christopher Helm April 2003 Price ?35. See Fatbirder Review

ISBN: 0713660201

Buy this book from NHBS.com

Other Links

Common Loon Video

Website

A Cornell Lab of Ornithology video clip…

Red-throated Diver or Loon Gavia stellata

Calls

Photographers & Artists

Black-throated Diver/Loon Gavia arctica

Video

You-Tube -

Red-throated Diver or Loon Gavia stellata

Image

White-billed Diver or Loon Gavia adamsii

Image