Blue budgerigar mutation

The blue trait maps to a single amino acid substitution (R644W) in an uncharacterized polyketide synthase (MuPKS) gene.

In combination with the Dark budgerigar mutation the body feathers become deeper shades of blue.

The Blue mutation[2] made its first recorded appearance in 1878[3] in the aviaries of M Limbosch[4] of Uccle, a suburb of Brussels, but this strain died out, it is believed, in 1881.

Blues appeared independently in the Netherlands between 1881 and 1885, and a Mr Pauwels of Everberg, near Brussels, reintroduced them to Belgium from this Dutch strain.

[3] The first Blues to be seen in England were some exhibited by Messrs Millsum and Pauwels at the Horticultural Hall in 1910 and the Crystal Palace in 1911.

[3] Blues remained quite rare until the 1930s, fetching up to £100 per pair in Japan around 1928, about the cost of a car at the time.

That is, the presence of a single wild-type allele is sufficient to permit the full production of the yellow psittacin pigment.