Wikipedia
Svarthöna, Bohuslän-Dals svarthöna, or Swedish Black Rooster, Hen or Chicken is a Swedish breed of domestic chicken that is considered to have originated with chickens transported from Mosambique to Norway by sailors sometime in the 17th century. Since then the breed has adapted to a northerly climate, but has retained the rare quality of black skin and connective tissue.
The current form of Svarthöna has been given the status of a landrace breed, and all Swedish entries in gene banks can be traced to a group of chickens that came to Sweden around the turn of the 19th century. In the year 1956 this flock was bought by two brothers in Bullarebygd. The Swedish Association for Landrace Breeds has preserved this breed in a gene bank since 1991.
A rooster can weigh up to 2 kg, whilst hens do not exceed 1.5 kg. The eggs are small (38-48 g) with a large yolk. Svarthöna is a breed fond of taking to the wing.
The black pigmentation found in skin and connective tissue has been shown to be the caused by a variant of the gene EDN3. A trait it shares with the Chinese Silkie chicken, the Indonesian Ayam Cemani, and the Vietnamese Black H'Mong.