Breed History; . . .
From the available written accounts the earliest approximate date that can be ascribed to the emergence of the Cayuga Black Duck is 1830; and probably from hybrids, as witnessed by Dr. Bachman. The American Poultry Society published its standard for the Cayuga Duck in 1867. Lewis Wright states that Cayuga Ducks were sent to him in Britain, from America, in 1871;and the breed first appears in the British Poultry Club Standards in 1874. By the 1890's the cayugas were measured at 19 pound per pair and resembling the Aylesbury in carriage They carry the blood of the original wild black duck, the Black East Indies,(See BEI page) and probably some Rouen blood introduced for the purpose of larger size. The Cayuga should be bred to the meat type. Desired weights are: Adult drake, 8 lbs.; adult duck, 7 lbs.; young duck, 6 lbs. Some Cayugas fail to attain these weights, and specimens of decidedly deficient size should not be bred.

. . A variety not usually met with, but which deserves to be better known, is that advertised by the Messrs. Baker as the Labrador Duck ; the Zoological Society have had it under the name of Buenos Ayres Duck, and received it from that place ; in the south of England it is known as the Black East Indian Duck. . . . . We may at once discard the claim of Labrador, however rich in wild specimens, to the honour of sending any new tame variety of bird. Believing that our Tame Ducks are all importations from the East, I should give the preference to the Indian title. Nothing is more probable than that the Zoological Society had their birds from the East, via Buenos Ayres. Whether the stock had been introduced there a month, or twenty years previously, does not alter the main fact ; while ships direct from India would be very likely to land a few pairs at the first Channel port they touched at. By some country dealers they are styled Beaver Ducks, in allusion, perhaps, to a black beaver hat. These persons esteem them highly, and usually send them to London alive, where, if good specimens, they are eventually disposed of to amateurs at the rate of eight or ten shillings each. But from whatever quarter obtained, they are handsome creatures. A little girl, at her first sight of them, could not help exclaiming "Oh! what beautiful golden-green Ducks!" The feet, legs, and entire plumage, should be black; a few white feathers will occasionally appear; but I had some birds that were immaculate, and such should be the model of the breeder. The bill also is black, with a slight under-tinge of green. Not only the neck and back, but the larger feathers of the tail and wings are gilt with metallic green ; the female also exhibits slight traces of the same decoration. On a sunshiny day of spring, the effect of these glittering Black Ducks sporting on the blue water is very pleasing, especially if in company with a party of the Decoy breed in strictly Mallard plumage. A peculiarity of these Black East Indian Ducks is, that they occasionally that is, at the commencement of the season lay black Eggs; the colour of those subsequently laid, gradually fades to that of the common kinds. This strange appearance is not caused by any internal stain penetrating the whole thickness of the shell, but by an oily pigment, which may be scraped off with the nail. They lay, perhaps, a little later than other ducks, but are not more difficult to rear. Their voice is said to differ slightly a fact I have not observed : but they are far superior to others in having a high wild-duck flavour, and, if well kept, are in just repute as being excellent food when killed immediately from the pond, without any fatting. My attention was first called to them by a friend and neighbour, to whom I am indebted, not only for the information, but for handsome specimens. 1848  Teatise on the History  and Management of Ornamental Poultry

By the 1870' 80's in America listed as a common duck breed THE BLACK CAYUGA Has black plumage, approaching brown, with a white collar. It is not quite so large as the Aylesbury or Rouen, but of superior flavor, and with greater aptitude to fatten than either of the above mentioned breeds. It originated on Cayuga lake, in New York. It is hardy and a good layer weight six to eight pounds. ( A manual on Poultry )

 By 1895 The Cayuga is an American variety', jet-black in plumage, supposed to have originated near Lake Cayuga, New York, from a cross of Mallard and the
Wild Black, or Buenos Ayres duck. The standard weights for these are eight and seven pounds respectively. ( Biggle)

1870's + 1901 edition of  Lewis Wright  and many otherws by Wright " The black Cayuga duck is called after the lake of that name, and comes to us from America, though a large black duck which bred pretty true was known half Cayuga a century ago in Lancashire. The Ducks. first American specimens were sent to us by Mr. W. Simpson in 1871, and the late Mr. J. K. Fowler imported them a few years later. These early specimens were not very large, and were rather dingy in colour, and there is no doubt that they were crossed with Black East India ducks in order to get the green gloss of the latter. This was accomplished, but kept them still small ; and they were afterwards crossed, by some with Aylesbury  and by others with Rouen, to get size. Unfortunately with this the type was also changed, as the original birds had no " keels," while the modern English exhibition Cayuga has this feature very pronounced. It has thus been made an exhibition duck at the expense of popularity in the market. Owing partly to this change, perhaps, the Cayuga has never quite had its deserts ; for general consent attributes to it decided superiority in flavour over any other of the large breeds. It is now a large breed, very similar in shape to the Aylesbury, the plumage being a rich black, heavily glossed with green, the legs a sooty orange, the bill a leaden or bluish black, with an intense black splash in the middle and a black bean at the tip. The skin is very white. "

1904  The Poultry Book USA" An East Indian drake with our common white ducks will often produce blacks; and Mr. Henry Digby informed me that he got the larger-sized Cayuga ducks from a drake of the breed mated with the modern Aylesbury duck. The normal color is the strongest and most assertive, and black the next; while white is the most obtrusive, as showing a weakness or lacking of color-pigment, coming as it does in old birds, and yet from the young of these scarcely appearing as permanent until at least the second molt." That to me is pretty conclusive re the shared ancestry

1910 American Standards of Perfection :-
 CAYUGA DUCKS. Disqualifications. White in any part of plumage; twisted wing; crooked back; decidedly wry tail. (See general disqualifications.)
STANDARD WEIGHTS. Adult Drake 8 lbs. Adult Duck 7 lbs. SHAPE OF DRAKE AND DUCK. Head: Long, finely formed. Bill: Long, top line slightly depressed. Eyes: Full. Neck: Of medium length, slightly arched. Wings: Short, folded closely and smoothly against sides.
Back: Long, broad. Tail: Only slightly elevated; composed of hard, stiff feathers; sex
feathers of drake, hard, well curled. Breast: Broad, full, prominent. Body: Long, deep, broad. Legs and Toes: Thighs, short, large; shanks, of medium length and size. Toes, straight, connected by web. Carriage of Body: Nearly horizontal.
COLOR OF DRAKE AND DUCK. Bill: Black. Eyes: Dark brown. Shanks and Toes: Dark slate or black, the latter preferred. Plumage: Lustrous greenish-black throughout, except primaries of duck, which are sometimes dark brown.