You can translate the Dutch part of the site with Google or Bing translate (right click on the page)
The Dutch Poultry Society was established after the Draconian mass slaughter of smallholders’ healthy poultry during the bird flu. A lot of resistance was born. The community actively resisted the government policy, and the result was tremendous: no more killing of healthy birds. Owing to our expanded international friendship,
we decided to alter the name to the European Poultry Society. So, News and Activities will shortly appear in two languages.
The EPS is not an association or foundation with difficult internal rules. |
 |
 |
A regular newsletter will appear on our website. We will you keep updated with interesting facts about the poultry in our hobby. It will cost you €15 to be a member of our Society. The amount can be transferred |
Eclipse Plumage in Domestic Ducks
In summer, something very strange happens to the ducks. They appear to change sex! Don’t let it worry you, but it happens to most species of ducks in the northern hemisphere. Shortly after the breeding season, the male moults and takes on a plumage similar to the female’s. Even the youngsters do it—all of them. When they have lost the fluffy down and feathered up for the first time, it is very hard to tell which are the young ducks and which are the young drakes. In their ‘juvenile’ plumage they all look much alike. With a bit of practice, you can spot the males by the slight difference in the bill colour and slightly darker patches on the rump. So what’s going on here, and why do they do it?
It begins in the early summer and lasts until the second moult of September (for the adults). They call it the ‘summer’ plumage or the ‘eclipse’. The drake ceases his posturing and fighting. He loses his bright nuptial livery and he skulks in a drabber than drab feather form. In fact, he deserts the female, who is now preoccupied with her brood, and retires into seclusion, either by himself or with a gang of male cronies down the river. I almost said ‘down the pub’. He has lost it. No sex appeal. Nothing to strut about. All he can do is sulk and try to stay out of trouble.
And that is the nub of it. I suppose there is no point in being conspicuous and flashy if the girlfriend is no longer interested. All that lustrous green head, sharp white collar and rich claret bib—all it would do is attract the predators! What the girls have learned, during the millennia of evolution, is to blend in to the background. They are well equipped with camouflage pattern feathers to sit out the incubation amongst the reeds, branches and grasses. Like hen pheasant, they can sit still and watch the fox or human go by. Only those males that evolved the same strategy have managed to survive.
This phenomenon is most apparent in ducks that have noticeable ‘sexual dimorphism’ in plumage colour and markings—the males are radically different from the females. Mallards are the classic example, and this involves most domestic ducks. They are really just mallards too. So, if you have Rouen Ducks, Silver Calls or Trout Runners, you will have seen this ‘eclipse’ take place every year. Funnily enough, something also happens to the females. They go a bit darker and blotchier during this period. If anything, the two sexes seem to get a little closer together in appearance, if nothing else.
Arthur Walton’s 1937 paper ‘On the eclipse plumage of the mallard’ gives a clear account on the major changes in the drakes. They ‘involve alteration of shape (tail centrals), decrease in pigmentation (under tail coverts), increase in pigment (flank), change from vermiculated to self-coloured (flank and scapulars), increase in brown pigment (breast, flank, belly and vent), loss of iridescence (neck), increase in regional differentiation (dark streak through the eye) and decrease in regional differentiation (loss of white neck ring).’ It is a most sophisticated and complex process. I suppose we can speculate ‘why’ it happens, but it is even more fascinating to enquire about ‘how’ it happens.
Just a little story first: some years ago our glamorous Tina (short for Argentina), the beautiful Silver Call, lost her looks. [‘argent’ = ‘silver’ (get it?)] Her head went dark; she developed a white neck ring and claret chest. She even stopped quacking quite so much (mercifully) and she grew slightly curled tail feathers like the males. In appearance, she genuinely changed sex. The question is why should this occur and what had happened to her body chemistry? It’s all to do with the endocrine glands, those that secrete hormones. Birds have only one working ovary. If that is damaged or diseased, it ceases to produce female hormones such as oestrogen, and it is these hormones that actually cause the ducks to have their female plumage. Strange as it may seem, the male plumage is the ‘default’. It does not matter if the male is producing his hormone (testosterone) or not. His winter plumage will remain the same.
OK, so why does the male change to female in summer? If he has the default plumage that is unaffected by his male hormone, why does he go ‘all girly’ out of the breeding season? One reason I quoted Arthur Walton’s Cambridge paper was to look at some of the early work on this very question. In, by modern standards, quite rough and ready experiments, Walton looked at the influence of artificial light on some drakes and castration on some others. It does not sound very appetising and a few actually died during the operation. Nonetheless, the results were quite interesting.
By increasing the duration of light (put on at dusk until 11 pm), drakes were encouraged to go into first moult some months ahead of a control group that had no artificial lighting. The eclipse lasted from early February until mid May. Normally it would be from mid July until mid September. Thereafter the birds would attain normal nuptial plumage. So it would seem that exposure to light is the ‘trigger’ for the eclipse process. Is it the drake’s sensitive skin or his eyes that register the increase in lighting times during the summer months? Then what happens to his body chemistry?
In 1916, H D Goodale worked with Rouen ducks, which are almost identical to the wild mallard in plumage and undergo a similar if not quite so well-marked eclipse. Goodale claimed that by removing the testis on both sides of the body of juvenile and adult drakes (normal or eclipse plumage) there was a ‘definitive assumption of normal plumage at subsequent moultings and the birds did not show any seasonal change. Incomplete or unilateral castration did not affect the plumage changes [Walton].’ As long as there was no regenerated tissue, Walton also found that castration ‘did not prevent the assumption of eclipse in the first year but did so in the second.’
So, if removal of testosterone (the male hormone) has no effect on the normal male plumage, why on earth should it stop the effeminate eclipse plumage? One would have thought that it would involve female hormone, not male hormone! Perhaps we could learn something from the chickens.
Significant research in the 1980s showed how Sebright and Golden Campine male fowl had ‘hen feathering’. Counter to the normal assumption that the male phenotype in this area is the default, how can male Sebrights look like females and still have all the other male functions? If they are sexually active, fertile and still generating male hormones, why do they look like hens? Wolf in sheep’s clothing or trans-sexuals?
It seems counter-intuitive, but the male hormone in Sebrights actually causes the production of female hormone. F W George and his fellow researchers have shown that testosterone can be converted into 17β-oestradiol in the skin of the male birds. Without testosterone they remain ‘cock feathered’. With the male hormone they are able to metabolize extra female hormone and thereby adopt the female plumage pattern. Amazing!
In Sebrights and Golden Campines, a specific gene has been identified, the autosomal dominant (though sex-limited) ‘hen feathering’ gene (Hf). Sebrights and Golden Campines are expected to be homozygous for this gene (Hf/Hf). Other breeds are expected to be homozygous for the alleles that allow cock feathering (hf/hf).
But is this what happens in drakes and young ducklings? What are the mechanisms that make drakes and ducklings ‘duck feathered’? As early as 1908 C W Beebe kept Scarlet Tanagers and Bobolinks in dark confinement. They retained their nuptial plumage all winter and summer long. In 1911 J C Phillips kept Mallard call ducks in the fridge! In a cold storage room actually, with a temperature range of 22-30 degrees Fahrenheit, though mainly around 25 degrees. ‘It was practically dark, though lighted at times with electricity.’ They too showed no sign of eclipse and retained their normal nuptial plumage. The disappointing thing, however, is that he failed to give his control group the same amount of lighting, therefore making it impossible to assert whether the cold itself had any effect on the lack of summer moult. We are left with the obvious question: is it something to do with prolonged exposure to sun-light that brings on the eclipse? If so, where are the light receptors (in the skin or in the eyes)? What is the actual process that activates the hormones?
A more up to date article by Owens and Short, ‘Hormonal basis of sexual dimorphism in birds’ (Tree vol.10, 1995), looks at the hormones acting on plumage and behaviour in many species of birds. The main focus though is on sexual selection (sexual characters as signals of quality). They point out that the problem is not new. People were wondering about the ‘sex-change’ of Lady Tynte’s peahen back in 1780, yet the exact process of how the male duck seems to go back and forth (during the course of a single year) between male and female attire is still somewhat mysterious. The amount of light, or the length of exposure, the sense mechanisms and body chemistry are rather vague; unless, that is, someone has been researching the problem of ‘summer plumage’. Call it ‘eclipse’ if you like, but more light needs to be shed on the problem.
***************************************
Silver Ducks in Perspective
by Chris Ashton
Our exhibition birds and their huge variety of colours tend to be taken for granted. Yet it’s only since 1982 that so many colour mutations have been accepted in the show pen, and only in the last decade or so that the varieties have exploded into the colour mixtures of the Call ducks found in both the UK and USA today. However, European paintings, even dating back to the seventeenth century, illustrate potential oriental sources for some of these mutations.
Colour mutations have often been referred to as ‘sports’ in the past, the variant seeming to arise inexplicably from a uniform flock of birds. Nothing need be further from the truth. The colours of these ‘sports’ may simply be the expression of recessive genes lying hidden, and waiting to be revealed as homozygotes, in what are often termed ‘closed flocks’. Despite these new colours and combinations being recognised in Europe and the USA, the origin of all them is unlikely to have been European. Some probably have a much more distant and colourful past.
For thousands of years, ducks were just ducks – the wild ones. Then people began to domesticate them. It certainly started earliest in China, perhaps as long as 4000 years ago, and in Indonesia where the Indian Runner evolved in the islands of Lombok, Bali and Java. This long history of domestication of the duck in the paddy fields of south East Asia has meant that there have been far more opportunities for de novo mutations (1) in the vast flocks of South East Asia compared with the relatively recent history of duck culture in Europe and the UK. It is therefore suggested that some of the colours we see in the domestic duck today – especially light phase (li), mallard restricted (MR) and the brown dilution (d) – came from the Far East.
The mallard duck did evolve in the west too, but much later, and on a smaller scale. For centuries, birds in Europe were just trapped in duckeries and decoys, which delayed domestication because they were so readily caught from the wild. So there is little evidence of the effect that domestication had on the colour of domestic ducks in Europe, because they simply were not bred in large commercial flocks until the 1700s or even later.
Dutch paintings from the Golden Age
Early evidence of domestication and the changes it brought in size, shape and colour, comes from Holland. During the 1600s the economy grew through international trade: people had money to spare and could afford to pay Dutch painters, who left a unique legacy of everyday life. It is estimated that no fewer than five million such paintings were executed in Holland in the seventeenth century, the Golden Age.
Some of the artwork included waterfowl on the table, in the backyard, and in collections on estates. Rich people wanted to show off their status and exotic new varieties were extremely fashionable. This fashion coincided appropriately with the newly forged colonial trade in the East Indies. One early record of the variety in ducks is found in Jan Steen’s Poultry Yard (1650) where he paints a white crested duck and depicts birds with the pied gene, which would go on (with the bibbed gene – thought to be European) to make the Magpie pattern.
Crested and pied birds are found in Indonesia today, and the inference is that both of these genes were found in mutations in the vast duck population of the Far East. Birds and their eggs were certainly transported from the Dutch East Indies by the sailing ships of the VOC (Dutch East India Company). The Dutch are sceptical about the crested gene arriving from the East Indies, perhaps because The Poultry Yard depicts a crested mallard, not an upright duck.
The pied gene is even more enigmatic. Pied Fawn-&-white birds were painted by Wyntrack (Wijntrack) in the 1600s, and we do not know if the pattern was European or Asian. However, the associated brown gene in these Fawn-&-whites of Wyntrack is crucial – the brown gene arrives in Europe with the Runners from Indonesia.
One of the greatest Dutch animal painters is Melchior d’ Hondecoeter. Depicting birds was a tradition in the d’Hondecoeter family. Gillis d' Hondecoeter (c. 1570-1638) painted landscapes with domesticated and exotic birds and animals, and his son Gijsbert d' Hondecoeter (1604-1653) also painted birds, particularly waterfowl and poultry.
The grandson, Melchior d’Hondecoeter, became known as the ‘Raphael of bird painters’. He was born into a family of artists and studied both with his father Gijsbert and his uncle Jan Baptist Weenix. His paintings can be found in several museums, including those of the UK, and show crested Hook Bills, a white Crested duck, and magpie Muscoveys with their small black&white magpie-marked ducklings.
Of all the seventeenth century bird paintings I’ve managed to find so far, none seems to have depicted ducks with harlequin or restricted mallard genes. Dirck Wyntrack and Joris van der Haagen depict brown, pied birds (fawn&white), and the blue dilution is there, but one seems to have to wait until Victorian times to get an indication that restricted mallard and harlequin phase genes had arrived.
Victorian farmyard ducks
Farmyard scenes were popular with Victorian artists. White ducks were a familiar theme, but what really catches the eye is the farmyard ducks of George W.
Horlor. ‘A family question’ (1880) shows a pair of ducks: an apparently white duck with a wild-colour mallard drake – and a rather mixed brood, which probably influenced the title of the painting. Horlor, it seems, is commenting on the six ducklings, five of which sport the Mohawk stripe. Since we now know that even a first cross of a mallard with mallard restricted results in Mohawk ducklings, one is left in no doubt that the white duck was hiding the restricted gene.
The date of the painting is timely. The Pekin was introduced into Britain and the USA between 1872 and 1873, and these duck genes soon circulated in Europe and America. It most likely brought with it the restricted gene. Just look at pictures of baskets of Far Eastern ducklings (2) and one also sees the same pattern today.
Evidence for the harlequin gene in art
The harlequin gene in ducks is called ‘silver’ (3). In its homozygous form it lightens the plumage in the duck. In the drake, key characteristics are a complete neck ring, fringing on the feathers of the claret bib, and extension of the claret along the flanks.
When do these birds appear? This gene does not seem to be expressed in the Far Eastern duck flock. It does not appear in the early Dutch or Victorian paintings and may not have come from the Far East, for the Silver Runner is a recent invention in Germany. It may indeed make its first recorded appearance in Mrs Campbell’s ducks in the photograph in Harrison Weir, published in 1902.
It was not, however, an isolated occurrence. The silver gene is illustrated by Alexander Koester (1864 -1932), who trained at the Karlsruhe Academy from 1885. He produced a large number of duck paintings, and the artist became known as ‘duck-Koester’ when his paintings became very popular. They developed from detailed and realistic illustrations in the 1890s to an Impressionist free brushstroke style, beautifully suited to the wind in the plumage, in his later works (4). In 1904 Koester was awarded the gold medal at the world fair in St Louis for his painting 'Enten'.
His most interesting paintings are the ones with coloured ducks: he shows the Runner pattern in fawn & white, as well as bibbed ducks, the magpie cap in mainly white ducks, a light phase mallard and most useful of all – a harlequin drake in Enten in Wasser unter Birken, and a silver duck (i.e. harlequin phase) in Eleven ducks in the morning sun. The actual date of the paintings is as yet unknown but they seem likely to have executed in the first two decades of the 1900s. Alexander Koester’s pictures can be found by searching under his name, on the internet, on several art websites.
Enten in Wasser unter Birken
THIS IS OFF THE INTENET
Eleven ducks in the morning sun THIS IS OFF THE INTENET
Abacot Rangers (the German Streicher) in the morning sun, showing typical male plumage of the green head, white neck ring and claret feathers extending along the flank.
The Abacot duck on the left is much more heavily marked than her sister, from the same hatch. The darker duck is similar in colour intensity to the female figured as Hunter’s mallard in his paper ‘A Light Mutant of the Mallard Duck’ 1939. His silver females were produced from ‘normal’ mallard stock. Harlequin phase is recessive to dark phase, and the silver ducks would seem to just appear in the individuals which happened to be homozygous for the gene. This effect was noted in Call ducks in the 1990s when Blue and Apricot Silvers‘appeared’ from parent Apricot and Blue Mallard Calls which had, in fact, been crossed with Silvers.
A similar Streicher to the one featured in ‘Eleven ducks in the morning sun’ by Alexander Koester is shown on the right. As noted in the Report of the Committee of European Poultry Standards, March 2010, there is considerable variation in the body marking of the female Streicher (Abacot Ranger). Absence of streaks on the flank and body feathers are a serious defect; nor should there be excessive striations. However, markings on Silver ducks do vary with the time of year, and particulary with age.
The Silver Call (silber-wildfarbig) at Hannover, Germany, 2009. This colour is very simlar to the American Snowy Call and the Dutch Meeskleur which should be dusky (no eye-stripes on the head to ruin the hood effect)
It is around this time too, that Frank Finn, 1913 (5), comments on the variations in ducks in the London Parks. Of particular interest is the reference to the drake where ‘reddish brown of the breast is continued along the flanks and sometimes onto the shoulders, while the upper parts are paler grey, often nearly white’. This is of course what distinguishes the harlequin phase in the drakes. In his text, Finn also distinguishes the dusky, and indicates that the park ducks have restricted genes (not yet named, but indicated by yellow ducklings with a dash of black on the crown).
From this point onwards, the harlequin gene becomes almost official. The
Abacot Ranger colour type – first produced by Mrs Campbell – re-emerges and is recorded around 1917, and Hunter’s Mallard is described 1939 (6, 7). Hunter’s five birds hatched in 1938 were typical harlequin ducklings in the fluff – light yellow with smoky-coloured down on the head and tail. The adult birds illustrated are typical harlequin phase: the duck with a distinct hood and streaked body, the drake with extensive claret on the flanks. This photograph can leave us in no doubt that these birds, which are very similar to Koester’s ducks, are indeed hooded silvers. Hunter has simply ‘found’ the recessive harlequin gene in his flock of what he identified as ‘mallards.’
Silvers are therefore not ‘new’, but the origin of the harlequin gene is simply
not known. There is no evidence that it came from the Runner or the Pekin. It could have been a de novo European gene. Who knows at this point? What we do know is that the colour is very popular, was first found in the light ducks, and was subsequently transferred to the Call duck by the 1920s and to the Indian Runner at some point in Germany. If German readers would like to contribute more information, that would be excellent. In the meantime, more information on the Silver Calls will appear in a further edition.
Silver Runners bred by ourselves in two generations from a single Silver drake and appropriate females. These birds are harlequin phase duskies. In Germany, like the Silver Call, they are called silber-wildfarbig (silver-wildcolour). The harlequin gene with dusky mallard expresses a claret bib in the males. In contrast, dusky, dark phase drakes have no bib and are pigmented under wing. Note that there is very close correspondence on the continent, in the UK and in the USA, in the colour called ‘silver’.
References
1. De novo: an alteration in a gene that is present for the first time in one family member as a result of a mutation in a germ cell (egg or sperm) of one of the parents or in the fertilized egg itself
2. Ashton, C&M, Keeping Ducks and Geese, David & Charles 2009, page 34
3. Lancaster, F.M., 1963 ‘The inheritance of plumage colour in the common duck’ (Bibliographica Genetica)
4. http://de.wikipedia.org/wiki/Alexander_Koester
5. Finn, Frank, Variation in Mallard Ducks, Avicultural Magazine, 1913
6. Hunter, Isaac, R ‘A light mutant of the mallard duck’, The Journal of Heredity,1939, Vol. 30
7. Ashton, M, ‘Silver Ducks’, Fancy Fowl, Feb 2010
More info in ‘Colour Breeding in Domestic Ducks’ on www.ashtonwaterfowl.net