Red Throated Diver { Birds of Europe}

Red Throated diver Gavia stellata

Originally posted to Flickr uploaded by Snowmanradio
Originally posted to Flickr uploaded by Snowmanradio | Source

Introduction

The Red throated diver or Loon as it is known in America,belongs to the order of birds known as the Gaviformes and the family Gaviidae within that order. The genus name of Gavia derives from a sea bird described by Pliny. the specific name of stellata derives from the Latin stellaris meaning starry.

In the UK they are placed on the Amber list of conservation concern { declines of between 25-50% over the last forty years or so } and is classed as a migrant/resident breeder and a passage winter visitor. The UK population is estimated at 1300 pairs in summer. In Ireland it is Amber listed due to European concerns for the species.There is a very small breeding population in County Donegal. In Europe it is classed as 3 concern with most in Europe depleted. The estimated European population is estimated at between 12-42,000 pairs. { Source BTO }

The European population varies greatly from country to Country, with for example Greenland an estimated 5,000 .breeding pairs, Iceland 1000-2,000 breeding pairs, Norway 2,000-5,000 breeding pairs, Sweden 1200-1,400 breeding pairs, Finland 900-1000 breeding pairs and Russia 20,000 + breeding pairs.{ source Birdlife}

It breeds in Europe,north Eurasia and North America. Winters south to southern Europe,SE China and the southern United States.

The Gaelic name for the bird is Learga-ruadh, the Welsh Trochydd Gyddfgoch and the Irish is Lma rue

Crossley's ID Guide to Britain and Ireland. Richard Crossley
Crossley's ID Guide to Britain and Ireland. Richard Crossley | Source

What are Divers or Loons.

The Loons { a name mainly used in North America } or Divers { A name mainly used in the UK and Ireland} are a group of Aquatic birds. All the living species are placed in the genus Gavia,the family Gaviidae and the Order Gaviiformes. The term Gavia was only transferred from the ducks to Divers/Loons in the Eighteenth century.

They are about the size of a large duck or small goose. The divers of this genus have toes connected by webbing. They tend to swim low in the water unlike ducks and geese and more in common with the Cormorants.

It has been said that when they are flying they resemble a goose with seagull's wings,which are relatively small in relation to their body size. They tend to hold their heads pointing slightly upwards when swimming. In flight the head tends to droop rather more than in other similar aquatic birds. They are excellent swimmers, their feet used to propel themselves above and under the water.,using their wings to provide assistance in the latter case.

because like grebes,their feet are placed well back on the body they find walking on land an inconvenience and rarely take to land unless when they are nesting. Although they are superb flyers they have a degree of difficulty taking to the wing,and need to swim into the wind in order to take off. Only the subject under review can take off from land.

It is thought that the divers/loons can hold their breathe under water for ninety seconds or more. They find their prey by sight.The prey being mainly fish supplemented by amphibians,crustaceans and other aquatic animals such as crayfish,frogs,and snails. To aid in the digestion of their food they take small pebbles from the bottom of the lakes and lochs and swallow them.

The five living species of this genus is the Black throated diver/loon, Gavia arctica. The Pacific loon Gavia pacifica {formerly G,arctica} Great northern loon{common loon} Gavia immer., the Yellow billed loon,or white bellied diver Gavia adamsii and the subject under review the red breasted diver/loon Gavia stellata

Red throated diver/loon in flight

Originally posted on Flickr, uploaded by Snowmanradio to commons.
Originally posted on Flickr, uploaded by Snowmanradio to commons. | Source

Description of the Red throated diver.

Male and female divers tend to have the same plumage during the winter months and the red throated diver's tend to be nondescript, greyish above fading to white below. During the breeding season it acquires the the distinctive reddish throat patch from which it takes its common name. The bill is sharply pointed,of a bluish horn colour, the upper mandible is straight, the lower one somewhat angular in outline. The red throated diver is a fine striking bird in breeding plumage the males weigh nearly three pounds.

The iris is red, the head on the sides and crown, the latter the darkest, and neck on the sides ,are a bluish grey variegated with paler spots and lines. The back of the neck and nape,almost black, but marked with short lines of white which give these parts a striated appearance. The chin is grey and also variegated with paler spots and lines.

The throat has an angular-shaped dark,red or reddish brown patch, the base of the angle lower most the apex upwards.The breast is white, the flanks greyish-black the centre of the feathers darker. The back very dark brown,nearly black,spotted with white,each feather having a paler margin. The tail is dark blackish brown, the tip white,under tail coverts white. The legs and toes dark brownish-green in front,the former paler behind,and tinged with purple blue ,the webs are dark brown.

Out of the breeding season the red throat patch becomes a greyish white colour.In rare cases some specimens keep their red throat patch ,but this is very unusual. The female is not so large as the male and the spots on her plumage are not so distinctly defined. The plumage variation occur at the early and latter parts of the year.

Birds of America .   John James Audubon
Birds of America . John James Audubon | Source

General and historical information

Butler 1896, who knew the bird by the scientific name of Colymbus septentrionalis {see below} remarks that the bird was a common breeder in the Shetlands,Orkney's and the Outer hebrides, but it is only a spring and autumn visitor to Skye,where, however, it has been known to breed.

In Autumn this bird migrates southwards and in winter may be encountered along the coasts of the UK and about the larger estuaries and harbours. Because of its habit of following the shoals of sprats and herrings it was known in the Thames by the name of 'Sprats Loon', in Pennant's day. The name Loon probably derives from the old English 'lumme' meaning lummox or arwkard person, or the Scandinavian word lum meaning lame or clumsy both alluding to the birds poor ability to walk on land.

The species was first described by a Danish naturalist Erik Pontoppidan in 1763, however, he first placed it in the now archaic genus of Colymbus,which included the Grebes as well as divers. By 1788, the German naturalist Johann Forster realized that Grebes and Loons were different enough to warrant a special genera and moved the Loons to their present genus.

Numbers in the USFWS surveys undertaken in Alaska revealed a 53% decline in population numbers between 1971 and 1993. There have been some declines also in parts of Europe. Conversely in Scotland the populations seem to have increased by 17% between 1994-2006.

The birds were once used by country people to forecast the weather. Records reveal this was the case even into the 1800's. Birds flying inland or giving but short cries was prelude to good weather. While those flying out to sea or uttering long wailing cries predicted heavy rain. It is still alluded to as the 'rain birder' in many localities.

It is remarkable how easily divers can be overlooked on the water,especially when the surface is rough,such is their colouring and ability to keep low to the surface.

Ready for take off.

Red throated diver in Iceland.
Red throated diver in Iceland. | Source

Breeding nest and eggs along with historical notes.

The Red throated diver resorts to freshwater lakes for breeding purposes and is said to prefer the shores of small pieces of water to islands in a larger loch,and also seems to prefer low islands, or shores, near the sea coast,to the more inland lakes. Studies have revealed that the male alone selects a location for the nest and they will fight to protect their territories which are usually in secluded localities.

Mr.W.R. Ogilvie Grant gives the following account of this species and its breeding habits. " In the north of Scotland, I have,on many occasions had many opportunities of watching the breeding habits of the red throated diver,and in May 1896 I spent several days in observing the behaviour of a pair who had a nest with two partially incubated eggs on the edge of a small loch.

" This species invariably selects the small desolate lochs,often mere pools,situated in the more lonely and deserted parts for nesting purposes. In the north of Sutherland, where the country is a mass of lochs of every size and shape, there is much ground suited to the habits of this diver, but for some reason only a few scattered pairs avail themselves of this fine tract of country.

" The two eggs are always placed close to the waters edge, either on the margins of a loch,or on some tiny islet, where the bank rises at a very gentle slope above the surface of the water. These birds are so curiously constructed- the legs being placed so far back on the long,boat-shaped body-that, though admirably adapted for aquatic life they are apparently incapable of standing upright on land. When leaving the water to gain the nest, the bird lies on its belly and slowly pushes itself up the gently sloping peat or turf bank, by using its legs alternately.

" Generally there are two short, distinct 'runs' leading from the nest to the water,doubtless made by the bodies of the birds being dragged over the soft wet ground as they change places during the period incubation. On one occasion,being anxious, if possible to secure the parent birds without shooting them, two carefully concealed 'gins' { trap} were placed just under the water at the ends of the runs, so that it seemed an absolute certainty that sliding bird must be caught by the legs either going to or from the nest. This plan however, utterly failed.

"Being hidden a couple of hundred yards off,we watched the female bird {for it was her turn on the nest} through the glass. three times she settled herself comfortably on the eggs,and as many times we frightened her off. But on each occasion she past over the traps without touching them, though the depth of the water could not have been more than two inches. On leaving the nest the parent bird glides gracefully off and quietly into the water,and if danger has been sighted,almost instantly dives,with scarcely a ripple,reappearing at a considerable distance from the nest.

" if the cause of the uneasiness is near at hand, the body is sunk low in the water until little more than the head and neck are visible,and it may easily be imagined that in the rough water the birds are most difficult to see,even with the help of the glass.When unconscious of the danger, the divers float and dive and preen themselves much like the ducks,often raising themselves to a semi-erect position in the water and flapping their wings. Some of the attitudes assumed by them when dressing their feathers are very curious.

" When preening the feathers of the sides and flanks, the birds turn half over,showing the white sides of the breast and belly,and when sorting the feathers of the breast they turn right over on their backs and float. if disturbed from the nest the birds circle high over the loch for some time the male uttering his harsh hoarse cry as he passes over head. Some authors describe the sound as reminding them of an 'Old cock grouse'"



Red throated Diver calling courtesy of P.C. KIng

Red throated diver with chick

Source
Divers are difficult to see on the water especially from a distance.  This at Mill Loch Eday. geograph.org
Divers are difficult to see on the water especially from a distance. This at Mill Loch Eday. geograph.org | Source

The nest ,eggs and young.

The nest sometimes consists of a collection of grass,rushes,or other easily available materials. At other times the eggs are laid on the turf,among stones,or in a slight depression in the ground with or without something in the way of lining. Dunn states that the eggs are so close to the waters edge that the sitting bird can touch the water with its bill. Contrary to popular opinion Loons do not pair for life,and studies have revealed that a male may have several mates during his life time.

The eggs no more than two are subject to considerable variation in size and colour. They are typically greenish or olive brown spotted with black. They are incubated for the most part by the female which begins after the first egg is laid. This period lasts for around 26-29 days before the chicks peck their way into the world. Soon after they are born the chicks are capable of diving and swimming if required. However, they tend to ride on their parents back during the first few days of their life, to conserve heat and energy and to avoid predators.But this fact is still disputed by some

The young chicks continue to be fed by their parents for about six weeks, then gradually gain in experience and begin to feed for themselves by the time they are twelve weeks old. By this time they may well have learned to fly.

In the young bird the bill is grey, with a tinge of yellowish red,the iris is reddish brown. The head,crown and neck on the back,and nape are grey finely streaked with greyish white. The throat and breast are white, the flanks marked with grey spots of an angular shape. The back is darkish brown or blackish-grey the edges of the feathers paler at the tips. The legs are greyish green in front the inner sides paler.

Juvenile red throated diver.

Source

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5 comments

D.A.L. profile image

D.A.L. 2 years ago from Lancashire north west England Author

aviannovice,

Hi Deb I thought you would be familiar with this species. I wish you luck in obtaining the pictures,if any one can do it you can. Look forward to seeing them. Have a great day. best wishes to you.


aviannovice profile image

aviannovice 2 years ago from Stillwater, OK

In Maine, we had the Common Loon, which gives a very haunting call in the still of a summer's night. They are beautiful, large birds that carry the babies on their backs. This sup ring migration, we should be going to the Texas/Louisiana coast, the wintering ground of the Common Loon. Hopefully, I will obtain pics of those birds not in breeding plumage, which is a lot different. A Common Loon showed up at Boomer Lake tho winter. It was in breeding plumage, but too far off for a decent picture. All I can say, is that it was recognizable.


D.A.L. profile image

D.A.L. 2 years ago from Lancashire north west England Author

Ericdieker,

hello, thank you so much. These birds do breed over there,so you are correct. Best wishes to you.

DDE,

Hi Devika, they are indeed beautiful birds,thank you for all the votes, they are much appreciated from you. Best wishes to you.


DDE profile image

DDE 2 years ago from Dubrovnik, Croatia

Wow! A beautiful bird indeed! I like the unique features of this bird. Voted up, interesting, useful and beautiful.


Ericdierker profile image

Ericdierker 2 years ago from Spring Valley, CA. U.S.A.

Very cool bird and a great hub. They look just like our birds here.

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