Gamebird hybrids are the result of crossing species of game birds, including ducks, with each other and with domestic poultry. These hybrid species may sometimes occur naturally in the wild or more commonly through the deliberate or inadvertent intervention of humans.
Mr. Hewitt, who has had great experience in crossing tame cock-pheasants with fowls belonging to five breeds, gives as the character of all 'extraordinary wildness' (13/42. 'The Poultry Book' by Tegetmeier 1866 pages 165, 167.); but I have myself seen one exception to this rule. Mr. S. J. Salter (13/43. 'Natural History Review' 1863 April page 277.) who raised a large number of hybrids from a bantam-hen by Gallus sonneratii, states that 'all were exceedingly wild.' [...] utterly sterile male hybrids from the pheasant and the fowl act in the same manner, "their delight being to watch when the hens leave their nests, and to take on themselves the office of a sitter." (13/57. 'Cottage Gardener' 1860 page 379.) [...] Mr. Hewitt gives it as a general rule with fowls, that crossing the breed increases their size. He makes this remark after stating that hybrids from the pheasant and fowl are considerably larger than either progenitor: so again, hybrids from the male golden pheasant and female common pheasant "are of far larger size than either parent-bird.' (17/39. Ibid 1866 page 167; and 'Poultry Chronicle' volume 3 1855 page 15.)"
Pheasant and grouse hybrids
Hybrids have been obtained between the "ornamental" species of pheasants e.g. Lady Amherst's, Silver and Reeves Pheasants.
- Capercaillie or wood grouse (Tetrao urogallus) and black grouse (Tetrao tetrix) in the UK
- Dusky or blue grouse (Dendragapus obscurus) and common pheasant (Phasianus colchicus) near Portland, Oregon, USA
- Sharp-tailed grouse (Tympanuchus phasianellus) and prairie chicken (Tympanuchus cupido) 
- Willow ptarmigan (Lagopus lagopus) and spruce grouse (Falcipennis canadensis)
- Dusky or blue grouse (Dendragapus obscurus) and sharp-tailed grouse (Tympanuchus phasianellus) at Osoyoos, British Columbia, 1906 (Dr. John W. Aldrich)
- Common pheasant (Phasianus colchicus) and prairie chicken (Tympanuchus cupido) at Ellendale, North Dakota, 1933
Charles Darwin mentioned crosses between domestic fowl and pheasants in Origin of Species
[...] from observations communicated to me by Mr. Hewitt, who has had great experience in hybridising pheasants and fowls
and later in The Variation of Animals and Plants under Domestication (top of this page), where he mentioned effeminate behaviour in the male hybrids.
In her book Bird Hybrids, A. P. Gray lists numerous crosses between chickens (Gallus gallus) and other types of fowl. Domestic fowl can be crossed, and produce fertile offspring, with silver pheasants, red junglefowl and green junglefowl. They have also produced hybrids with peafowl, chachalacas, capercaillie, grouse, quail, curassows, pheasants and guans.
Domestic fowl have been crossed with guineafowl and also with common pheasant (Phasianus colchicus). Domestic fowl/pheasant hybrids have also occurred naturally. Domestic chickens and quail (Coturnix coturnix subsp. japonica) have been hybridised using artificial insemination.
Chicken and turkey hybrids
There have been attempted crosses between domestic turkeys (Meleagris gallapavo) and chickens. According to Gray in 12 studies no hybrids hatched. Other reports found only a few fertile eggs were produced and very few resulted in advance embryos. According to Olsen, 23 hybrids were obtained from 302 embryos which resulted from 2132 eggs. Dark Cornish cockerels and Rhode Island Red cockerels successfully fertilised turkey eggs. Harada & Buss reported hybridisation experiments between Beltsville Small White Turkeys and two strains of chickens. When male chickens inseminated female turkeys, both male and female embryos form, but the males are much less viable and usually die in the early stages of development. When male turkeys inseminated female chickens, no hybrids resulted although the unfertilised chicken eggs began to divide. According to Olson turkey-chicken crosses produced all males.
A supposed turkey x pheasant hybrid was reported by Edwards in 1761.
Charles Darwin also described duck hybrids in The Variation of Animals And Plants Under Domestication:
Hybrids are often raised between the common and musk duck, and I have been assured by three persons, who have kept these crossed birds, that they were not wild; but Mr. Garnett (13/45. As stated by Mr. Orton in his 'Physiology of Breeding' page 12.) observed that his hybrids were wild, and exhibited 'migratory propensities' of which there is not a vestige in the common or musk duck.
Hybrids between mallard ducks and Aylesbury ducks (a white domestic breed derived from the mallard) are frequently seen in British parks where the two types are present. The hybrids often resemble a dark coloured mallard with a white breast. Mallard ducks also hybridise with the Muscovy duck producing pied offspring.
Hybrids between the ruddy duck and white-headed duck are undesirable in parts of Europe   where the introduced ruddy duck has bred with native white-headed ducks. The increasing number of ruddy ducks and hybrids threatens the existence of the white-headed ducks, resulting in shooting campaigns to remove the introduced species. This is controversial as some believe that nature should be allowed to take its course, even though this favours the more successful introduced species.
List of duck hybrids:
- Northern pintail and mallard
- Ruddy duck and white-headed duck
- Ruddy shelduck and shelduck
- White-faced whistling duck and plumed whistling duck
- Baikal teal and northern pintail
- Hooded merganser and smew
- Eurasian wigeon and American wigeon
- Mallard and grey duck, a subspecies of the Pacific black duck.
See also Mariana mallard.
Charles Darwin described hybrid geese in Origin of Species:
The hybrids from the common and Chinese geese (A. cygnoides), species which are so different that they are generally ranked in distinct genera, have often bred in this country with either pure parent, and in one single instance they have bred inter se.
Goose hybrids include Canada goose x greylag goose, Canada goose x domesticated geese, emperor goose x Canada goose, red-breasted goose x Canada goose, Canada goose x white-fronted goose and barnacle goose x Canada goose.
- Handbk Brit. Birds, 5: 210
- Anthony, 1899. Auk, 16: 180
- 1918. Wilson Bulletin, 30: 1-2, plate
- Taverner, 1932. Annual Report, 1930, National Museum of Canada, p. 89 with plate
- Gray Annie. P, 1958. Bird hybrids. Commonwealth Agri. Bureau, Farnham Royal, Bucks, England. Robt. Cunningham and Sons, Alva, Scotland. 1-390.
- Ghigi A. 1936. "Galline di faraone e tacchini" Milano (Ulrico Hoepli)
- Wheeler, H. J. 1910. A pheasant-bantam hybrid. Amer. Breeders Mag. 1: 266-268.
- Cutler, D. W. 1918. On the sterility of hybrids between the pheasants and the Gold Campine fowl. J. Genetios 7: 155-165.
- Serebrovsky, A. S. 1929. Observations on interspecific hybrids of the fowl. J. Genetics 21: 327-340.
- Yamashina, Y. (1942). "On the hybrid between the domestic fowl, Gallas gallus var. domesticus and the common pheasant, Phasianus colchicus". Japanese Journal of Genetics 18 (5): 231–253. doi:10.1266/jjg.18.231.
- Shaklee, W. E.; C. W. Knox (1954). "Hybridization of the pheasant and fowl". Journal of Heredity 45: 183–190.
- Asmundson & Lorenz, 1957
- Mitsumoto, K.; S. Nishida (1958). "Trials of production of the hybrid between quails and chickens". Ap. Zootech. Sci. 29: 10.
- Wilcox, F. H.; C. Elmer Clark (1961). "Chicken-quail hybrids". Journal of Heredity 52: 167–170.
- Poll, H. 1910. "Uber Volgelmischlinge" Ber. V, intern. Ornithologenkongress.
- Warren, D.C.; H. M. Scott (1935). "An attempt to produce turkey-chicken hybrids". Journal of Heredity 26: 105–107.
- Asmundson, V. S.; F. W. Lorenz (1957). "Hybrids of ring-necked pheasants, turkeys and domesticated fowl". Poultry Science 36: 1323–1334. doi:10.3382/ps.0361323.
- Ogorodii U. 1935. Hybridization of unrelated birds in Askania-Nova. Bull. All Union Academy Agri. Sciences (Lenin) 1:25
- Quinn, J. P.; Burrows, W. H.; Byerly, T. C. (1937). "Turkey-chicken hybrids". Journal of Heredity 28: 169–173.
- Olsen, M. W. (1960). "Turkey-chicken hybrids". Journal of Heredity 51: 69–73.
- Harada, K.; Buss, E. G. (1981). "Turkey-Chicken Hybrids: A Cytological Study of Early Development". Journal of Heredity 72 (4): 264–266. PMID 7288138.
- Edwards, G. 1761. An account of a bird supposed to be bred between a turkey and pheasant. Trans. Roy. Soc., London 51- pt. 2, B: 415-417
- Darwin, Charles. The Variation of Animals And Plants Under Domestication.
- Darwin, Charles. Origin of Species.
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