Black-throated Diver
Encyclopedia
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
.
in his 18th century work, Systema Naturae
. The genus name Gavia comes from the Latin
for "sea mew", as used by ancient Roman naturalist Pliny the Elder
.
. Body mass is reportedly from 2–3.4 kg (4.4–7.5 lb). They have a grey head, black throat, white underparts and chequered black-and-white mantle. Non-breeding plumage
is drabber with the chin and foreneck white. Its bill is grey or whitish and dagger-shaped. In all plumages a white flank patch distinguishes this species from all other divers including the otherwise almost identical Pacific Diver
.
and occasionally in western Alaska
. It winters at sea
, as well as on large lakes over a much wider range.
It is a vagrant
to Pakistan
.
, like all divers, is a specialist fish
-eater, catching its prey underwater. It flies with neck outstretched. It feeds on fish, insects, crustaceans and amphibians.
The calls include a yodelling high-pitched wail and harsh growls, similar but lower pitched than Pacific Loon.
See Gaviidae for more details on general behaviour
The Black-throated Diver is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
) applies.
Instructions for constructing and deploying artificial floating islands to provide Black-throated Divers with nesting opportunities are given in Hancock (2000).
On September 6, 2007, RSPB Scotland
and the Scottish Natural Heritage
(SNH) stated that it was surprised by an increase in the last 12 years in the breeding figures in the UK for the Red-throated Diver
and the rarer Black-throated Diver of 16% and 34% respectively due to the anchoring
of 58 man-made rafts in lochs. Both species decreased elsewhere in Europe
.
The Black-throated Diver is the current school emblem of Achfary Primary School
.
Dr Mark Eaton, RSPB scientist
traced the drop in overall numbers to warming of the North Sea
which reduced stocks of the fish
on which they feed.
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
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
International Ornithological Committee
The International Ornithological Committee is a group of about 200 international ornithologists, and is responsible for the International Ornithological Congress and other international ornithological activities, undertaken by its Standing Committees....
.
Taxonomy
The Black-throated Loon was one of the many species originally described by LinnaeusCarolus Linnaeus
Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...
in his 18th century work, Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
. The genus name Gavia comes from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "sea mew", as used by ancient Roman naturalist Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...
.
Description
Breeding adults are 58 to 77 cm (22.8 to 30.3 in) in length with a 100 to 130 cm (39.4 to 51.2 in) wingspan, shaped like a smaller, sleeker version of the Great Northern DiverGreat Northern Diver
The Great Northern Loon, Great Northern Diver, or Common Loon , is a large member of the loon, or diver, family of birds...
. Body mass is reportedly from 2–3.4 kg (4.4–7.5 lb). They have a grey head, black throat, white underparts and chequered black-and-white mantle. Non-breeding plumage
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
is drabber with the chin and foreneck white. Its bill is grey or whitish and dagger-shaped. In all plumages a white flank patch distinguishes this species from all other divers including the otherwise almost identical Pacific Diver
Pacific Diver
The Pacific Loon or Pacific Diver , is a medium-sized member of the loon, or diver, family. It may be conspecific with Black-throated Diver/Arctic Loon, which it closely resembles....
.
Distribution
It breeds in EurasiaEurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
and occasionally in western Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
. It winters at sea
Sea
A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...
, as well as on large lakes over a much wider range.
It is a vagrant
Vagrancy (biology)
Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...
to Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
.
Behaviour
This speciesSpecies
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, like all divers, is a specialist fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
-eater, catching its prey underwater. It flies with neck outstretched. It feeds on fish, insects, crustaceans and amphibians.
The calls include a yodelling high-pitched wail and harsh growls, similar but lower pitched than Pacific Loon.
See Gaviidae for more details on general behaviour
Miscellaneous
AEWA
The Agreement on the Conservation of African-Eurasian Migratory Waterbirds is the largest of its kind developed so far under the Bonn Convention. It was concluded on 16 June 1995 at The Hague, the Netherlands and entered into force on 1 November 1999 after the required number of at least fourteen...
) applies.
Instructions for constructing and deploying artificial floating islands to provide Black-throated Divers with nesting opportunities are given in Hancock (2000).
On September 6, 2007, RSPB Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
and the Scottish Natural Heritage
Scottish Natural Heritage
Scottish Natural Heritage is a Scottish public body. It is responsible for Scotland's natural heritage, especially its natural, genetic and scenic diversity. It advises the Scottish Government and acts as a government agent in the delivery of conservation designations, i.e...
(SNH) stated that it was surprised by an increase in the last 12 years in the breeding figures in the UK for the Red-throated Diver
Red-throated Diver
The Red-throated Loon or Red-throated Diver is a migratory aquatic bird found in the northern hemisphere. It breeds primarily in Arctic regions, and winters in northern coastal waters. It is the most widely distributed member of the loon or diver family. Ranging from in length, the Red-throated...
and the rarer Black-throated Diver of 16% and 34% respectively due to the anchoring
Anchoring
Anchoring or focalism is a cognitive bias that describes the common human tendency to rely too heavily, or "anchor," on one trait or piece of information when making decisions.-Background:...
of 58 man-made rafts in lochs. Both species decreased elsewhere in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
.
The Black-throated Diver is the current school emblem of Achfary Primary School
Achfary
Achfary is a hamlet in the Scottish council area of Highland. To the east of the village lies Loch nan Ealachan.It is owned by the Grosvenor Estate and is renowned for its unusual black and white telephone box, erected in the 1960s...
.
Dr Mark Eaton, RSPB scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
traced the drop in overall numbers to warming of the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
which reduced stocks of the fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
on which they feed.
External links
- IBC Videos on the Internet Bird Collection
- Flicker Field Guide Birds of the World Photographs
- - BTO BirdFacts- Black-throated Diver
- - Bird page- Black-throated Diver
- Information and Illustration on Black-throated Loon (Arctic Loon) from A Field Guide to Birds of Armenia