Crested (duck breed)

The Crested is a breed of domestic duck. It was probably brought to Europe from the East Indies by Dutch ships. It has its appearance because it is heterozygous for a genetic mutation causing a deformity of the skull.
History.
The Crested probably originates in the East Indies, with subsequent development in Holland. Crested ducks are seen in seventeenth-century paintings such as those of Melchior d'Hondecoeter and Jan Steen. Paintings as old as 2000 years have depicted images of a bird, resembling a duck with an assortment of feathers on top of its skull. In the United States the breed was described by D.J. Browne in 1853. The white Crested was added to the American Standard of Perfection in 1874; the black variant was added in 1977. The Crested was recognised in the United Kingdom in 1910. In the UK, as in several other European countries, any colour is permitted.
The crest is large and well centered on top of the skull. They have long, slightly arched necks, medium length body, much depth and fullness through the breast.
A bantam version of the breed, the Crested Miniature, was bred by John Hall and Roy Sutcliffe in the United Kingdom in the late twentieth century; it was recognised in 1997. The crested gene is very popular in Europe, resulting in crested versions of most breeds. Though Cresteds can be good layers and strong roasting qualities, the main interest and demand for the breed is as pets and decorations. They are not a popular show breed due to challenges associated with the crest. The crest often causes the ducks to bear a fat body in the skull. Depending on the fat body's size and relative position to the brain, it can impede a duck’s mobility. Many crested ducks experience a tottered walking pattern and if knocked over are unable to get up. Other issues caused by the fat body may include seizures, neurological problems, and even early death. 
Breeding.
When two ducks heterozygous for the crested allele breed, their eggs are in the usual 1:2:1 genotypic ratio, but live offspring are in a 1:2 ratio as explained below:
The offspring of a duck with a crest and a duck with no crest are expected to be 50% with and 50% without a crest.