Cygnus Cygnus Research Articles

The incidence of lead poisoning among whooper and mute swans Cygnus cygnus and C. olor in Scotland

A number of incidents were reported between 1980 and 1986 involving the deaths of substantial numbers of whooper swans Cygnus cygnus in Scotland. Post-mortem examinations identified this to be due to lead poisoning in 47% of these cases. Gizzard contents indicated that most of the lead came from shotgun pellets. In contrast, examinations of mute swans Cygnus olor found dead in Scotland over the same time interval indicate that only 13% died of lead poisoning, and most of these were isolated birds from a wide variety of locations. Mean lead levels in kidney tissue of poisoned whoopers was 223 μg g −1 dry weight compared to 661·9 μg g −1 dry weight in mutes; both these values were considerably lower than the values recorded among poisoned mutes in England. Blood lead levels in whoopers in Iceland had a median value of 31 μg 100 ml −1 compared to 48 μg 100 ml −1 in Scotland, indicating that the lead was being ingested in their wintering grounds in Scotland. The median blood level in Scottish mute swans was 52 μg 100 ml −1. Both of these values from Scotland are high when compared to the ‘maximum acceptable level’ of 40 μg 100 ml −1 suggested by Birkhead (1983). Differences in feeding location, diet, and requirements for grit between whoopers and mutes are considered responsible for different levels of exposure to lead in the environment, and susceptibility to poisoning. Two sites in NE Scotland have been identified as having densities of lead pellets high enough to be potentially dangerous to waterfowl. Both of the sites can be associated with high-intensity shooting and are used frequently by swans for gritting. The relatively low incidence of split shot in poisoned swans in Scotland, compared to the situation in England, is thought to reflect the tackle and techniques of game-fishing rather than coarse fishing in Scotland.

The microclimate of the nests of waterfowl

A sophisticated radiotelemetry system was used to monitor continuously the temperature, relative humidity and the incidence of parental movement sufficient to admit light to, or turn the eggs in, the nest cup of (number of days recordings m parenthesis): Black Swan Cygnus atratus (68); Barnacle Goose Hrantal leucopsis (70); Whooper Swan Cygnus cygnus (28) and Greylag Goose Ansev anser (26). The following features were common to all the nests: (1) a slow rise in the temperature of the nest cup with the onset of incuhation; (2) a temperature gradient in the vertical plane of the nest cup throughout incubation; (3) a diurnal rhythm in the temperature and humidity of the nest cup, this being caused by bird behaviour rather than the ambient environment; (4) nesting materials dried out during incubation thereby accentuating the steepness of the diffusion gradient between a real egg and the atmosphere of the nest cup; (5) the eggs, which were turned between 0.594.95 times an hour, were rotated mainly around their long axes.

Winter Feeding Methods of the Whooper Swan (Cygnus cygnus)

Winter Feeding Methods of the Whooper Swan (Cygnus cygnus)

A Case of Unusual Aggression by a Whooper Swan

A Case of Unusual Aggression by a Whooper Swan

Wildfowl of the Inner Hebrides

SynopsisWildfowl habitat in the Inner Hebrides. Excluding Islay, consists mainly of sheltered bays and sealoches, while fertile freshwater lochs are uncommon, the best being on Tiree. The known breeding distribution and winter concentrations of species are described and an indication is given of overall status and histroical background. There are very few records from many of the smaller islands, and even those from Skye, Tiree and Mull are restricted to between one and four winters.Eider and red-breasted merganser are probably the two commonest wintering speices, but there are no good estimates of total numbers. Flocks of 500–600 eider occur round Skye, and summer moulting concentrations of 1.400–1.700 merganser in the Sound of Gigha indicate a high pouplation. Between 2.400–2.600 barnacle geese Branta leucopsis spend the winter on many small. Uninhabited islands throughtout the region. Wigcon. Teal, mallard and tufted duck occur in flocks in several places, with maxima between 150 abd 350.Whooper swan Cygnus cygnus, Greenland white-fronted goose Anser albifrons flavirostris, shelduck, shoveler, pochard, goldeneye Bucephala clangula, long-tailed duck Clangula hymelis and goosander all winter regularly, though rarely in flocks of more than 100.

Wildfowl of Islay

SynopsisThe island of Islay posssesses by far the largest population of wintering wildflowl in the Inner Hebrides; there are 18,000-20,000 barnacle geese Branta leucopsis and 4,000 Greenland white-fronted geese Anser albifrons jiavirostris. There is also a small flock of greylag geese A. anser. Most of the commoner dabbling and diving ducks spend the winter in small numbers, with a flock of 1,000 scaup Aythya marila the most important. A few hundred pairs of eider Somateria mollissima breed, and up to 3,000 wintering or moulting birds have occurred offshore. Other breeding duck are few in number, including up to five pairs of common scoter Melanitta nigra. Whooper swans Cygnus cygnus spent the winter in the past but are now common on passage only. Barnacle geese have trebled in numbers in the last twenty years, leading to complaints of agricultural damage, and a subsequent increase in shooting and disturbance followed by a recent decline in numbers. Annual data on populations, productivity and losses are presented. Greenland white-fronted geese have varied less in numbers, but shooting has increased and the situation is reviewed. All other wildfowl occurring on the island are dealt with briefly.

SIZE, FORM AND HABIT OF THE EXTINCT MALTESE SWAN CYGNUS FALCONERI

SummaryThe giant extinct Maltese Swan is shown in this work to have been a land‐feeding bird, well adapted for walking but with little or no ability to fly. Fossils of the swan prepared during this study comprise the most representative remains in existence; the greater part of the foot skeleton and the frontal part of the cranium are described for the first time. By comparison of the bones with those of living swans I estimate that it probably resembled a scaled‐up Whooper Swan weighing about 16 kg and with a wing span of about 3 m.

The grazing of Zostera by wildfowl in Britain

In Britain there are four main species of wildfowl which use Zostera as a food source. The relative importance of Zostera in the diets of wigeon, brent geese, mute and whooper swans in discussed with reference to the published information.

A female "Crested" Whooper Swan Cygnus c. cygnus wintering at Hyoko in Niigata, 1976-77 winter

A particular female Whooper Swan Cygnus c. cygnus, wintering at the well known swan and other waterfowls resort, lake Hyoko, was kept under observation in 1976-77 winter. Here the swans and waterfowls are well tamed by artificial feeding. This particular female arrived at Hyoko in late December with her mate and 2 cygnets. In my first observation in December, her crown seemed to be somewhat unkempt, but it was not so curious.As the time went by her crown feathers became longer. This changing process is shown by Plates 13-16.

Two year observations of a family of the Whooper Swan Cygnus cygnus at Hyoko, Niigata

1. A particular female Whooper Swan and her family, wintering at a well known swan and waterfowl resort, lake Hyoko near Niigata City on Japan Sea coast of Honshu, were kept under observation of behavior in two successive winters. Here the swans (and other waterfowls) are well tamed by artificial feeding.2. This particular female could be identified by a pair of small yellow spots on both sides of the black part of the bill.3. In 1974-75 winter, she formed a family with her mate and four cygnets, but she returned in December 1975 with a male not accompanied by cygnets.4. Continuous observations of 4.6 hours and 6 hours were made on February 14, 1975 and January 30, 1976 respectively.5. Their movements were recorded every 2 minutes and the moving distance/per hour was 680m, on February 14, 1975 (with cygnets), and only 67m, on January 30, 1976 (withont cygnets).6. Although the lake condition partly caused the above difference of moving distance/per hour in 1975 and 76, because most of the lake surface except artificial feeding place was frozen in 1976, but all the surface was free from ice in 1975, the difference of family composition in the two years, with or without cygnets, was apparently correlated as mentioned below.7. The 1976 pair, without cygnets, responded quickly to the artificial feeding and after eating enough could rest on nearly ice not moving to a distance, but the 1975 family, with cygnets, arrived feeding place later than others and could not eat enough, thus moving away to continue feeding on natural food at other parts of the lake.

Winter Distribution of Whooper and Bewick's Swans in Ireland

A quarter of a century's personal investigations, culminating in an intensive survey over the winters of 1969–70 to 1972–73, has given a broad picture of the distribution and relative proportions of the two wild swans wintering in Ireland. An increase and expansion of Whooper Swans has taken place since about 1943, and more recently there have been signs of a growth in the population of Bewick's Swans.

CONTROLLED ANTIPHONAL CALLING BY WHOOPER SWANS

IbisVolume 116, Issue 2 p. 228-231 CONTROLLED ANTIPHONAL CALLING BY WHOOPER SWANS Joan Hall-Craggs, Joan Hall-Craggs Sub-Department of Animal Behaviour, High Street, Madingley, CambridgeSearch for more papers by this author Joan Hall-Craggs, Joan Hall-Craggs Sub-Department of Animal Behaviour, High Street, Madingley, CambridgeSearch for more papers by this author First published: April 1974 https://doi.org/10.1111/j.1474-919X.1974.tb00244.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume116, Issue2April 1974Pages 228-231 RelatedInformation

Waterfowl at Loch Leven, Kinross

SynopsisA large water surface, suitable islands for nesting, extensive shallows, rich adjoining farmland and comparative peace help to make Loch Leven internationally important for waterfowl. It has long held the largest concentration of breeding ducks in Britain, consisting in 1966–72 mainly of tufted duck (500–600 pairs) and mallard (400–450 pairs), but also of gadwall (20–30 pairs), wigeon (25–30 pairs), shelduck (5–18 pairs), shoveller (up to 10 pairs) and teal (up to 10 pairs). In winter, it was important for mallard, teal, pochard and in some years for shoveler, and held good numbers of wigeon and goldeneye. These various species differed in the proportion of their food which they obtained from the loch itself. The loch also acted as a winter roost for up to 5000 greylag geese, up to 12 500 pinkfeet and up to 430 whooper swans, all of which fed entirely in nearby fields. The numbers of most species underwent regular seasonal fluctuations, with peaks and troughs in the same months each year; but different species reached peak numbers in different months. In general, waterfowl numbers were greatest in autumn, when the loch held up to 20 000 birds.The status of several species at the loch has changed markedly during the last 100 years. Some such changes were linked with general changes in the ranges and status of the species concerned, but other (more recent) ones with the reduction in macrophytes following eutrophication.

Breeding of Whooper Swans in Iceland

Whooper Swans were studied on their breeding grounds on the ‘meadows’ of Iceland's central plateau, and a wide range of interesting observations and behaviour while nesting are summarised in this paper.

Changes in a Winter Herd of Whooper Swans at a Banff Loch

The author chronicles a steep decline in the autumn-winter herd of Whooper Swans frequenting what had long been a favourite loch in northeast Scotland. He suggests that re-afforestation around the loch shores may have made it an unsuitable habitat.

Histometric Study of the Avian Retinas

The thickness of the layers of retina has been measured in six avian species; i. e. Japanese jungle nightjar, feathered-toed scops owl, Japanese jay, whooper swan, Bering island guillemot, and donestic gallus. The former two are nocturnal and the latter four are diurnal.The layer of rods and cones and the inner plexiform layer are thicker in the nocturnals than in the diurnals. The outer nuclear layer, the outer plexiform layer, and the layer of ganglion cells show no significant difference in thickness among these species. In all birds examined, the inner nuclear layer is constantly thicker than the outer nuclear layer. The layer of optic nerve fibers is thicker in the diurnals than in the nocturnals.

Some notes on the swans, and on the main factors that caused their extensive death at Odaito Bay, Nemuro, Hokkaido

There are two species of swans in Japan. One of them is the Whooper Swan, Cygnus cygnus and the other is the Eastern Bewick's Swan, Cygnus columbianus jankowskii. Both of them come from the northern and north-eastern parts of Siberia to Japan and spend some six months in this country as winter bird. The earliest arrival in Japan is late in October and the last departure is the 28th of April, according to the past observation records.The main wintering areas of swans are Lake Toro (Kushiro), Lake Furen and Odaito Bay (Nemuro), Lake Tofutsu (Abashiri), Lake Utonai (Tomakomai), etc., in Hokkaido. In Honshu they pass the winter at Ohminato Bay and Kominato Bay (Aomori Prefecture), Lake Hyo (Niigata Prefecture), etc. A small number of swans (1-8 individuals) occasionally visit Arasaki, Kyushu.It seems that Odaito Bay is the most important wintering area in Japan, since about ten thousand Whooper swans stay there for six months (Fig. 1). There is no other comparative wintering area in our country.Odaito Bay is located on the eastern part of Hokkaido, between Shiretoko Peninsula and Hanasaki Peninsula (Fig. 2). The area of Odaito is estimated at about 51, 840, 000 square meters. Many kinds of seaweeds are found in this region, providing suitable food for the swans. In addition, during the winter many speciesof ducks stay in this area.As far as I know, Eastern Bewick's swans are rarely found in Hokkaido, while there are comparatively many of them in Honshu.About 200 Whooper swans died because of the cold wave at Odaito Bay in February, 1967. A period of successive low temperatures continued for two weeks (Fig. 3) The temperature began to go down on the 8th of February. We had never before heard that a great number of swans died from cold and starvation.I visited Odaito Bay two times, just before and immediately after the accident, and found that there had occurred a remarkable reduction in the number of subadult swans.On the 12th of February, 1967, 106 sub-adults (11per cent) and 893 adults (89per cent) out of the total number of 999 swans were observed. On the 26th of February, 1967 only 15 sub-adults (2per cent) and 873 adults (98per cent) out of the total number of 888 swans were found. Incidentally, about 16per cent (329 out of 2, 047) for sub-adults and 84per cent (1, 718 out of 2, 047) for adults were observed at Odaito Bay on the 12th of February, 1966 (from the colour films taken at random).The percentages of the adults and sub-adults were estimated from the colour films which were taken at random at Odaito Bay.In order to determine the cause of death in adult and sub-adult swans autop-sies were taken. There was found no food in any crop of the dead swans. Although no green seaweeds were seen in the gizzards of two sub-adults (Fig. 4), some grits were found. On the other hand, in the gizzard of one adult was found a trace of green seaweeds.We could not find externally any symptoms of disease on the various internal organs.It has been found that when the swans were healthy excreted solid fecal pellets (Fig. 5-A), but when they were weak they excreted diarrheic pellets (Fig. 5-B).It is desirable to stir the surface of the water mechanically or to make ripples by bubbling with an air compressor in order to prevent freezing of the sea water on cold nights so that the swans may have access to the seaweeds.

Soviet Studies in the Northward Movement of Birds

The warming of the Arctic, especially in the Eurasian sector, has been pronounced since the 1920s. The tundra moves into the arctic desert, the taiga into the tundra, and along with this the mammals, birds and plants extend northward. Study of these changes in zoogeographical boundaries by Soviet scientists shows that some birds have extended their ranges up to 130 mi northward, the willow warbler, meadow pipit, fieldfare and willow ptarmigan to 69° 50' N on Vaygach Island, 74° N Novaya Zemlya. From more southerly ranges the house sparrow has extended from 61° to 70° N, the chaffinch and rook 700 km from Krasnoyarsk to Komsa, the black woodpecker, coal tit, whooper swan and merganser 200-400 km in the Yenisey taiga. The fieldfare, eastern hermit thrush and robin are now established in Greenland, the gadwall in southern Alaska.

Whooper Swans at Loch Park, Banffshire, 1955–61

Whooper Swans at Loch Park, Banffshire, 1955–61

Further Observations of Whooper Swans in the Aleutian Islands, Alaska

Further Observations of Whooper Swans in the Aleutian Islands, Alaska