Yellowcheek (Dominant and Sex-linked)

yellowcheek2xYellowcheek (sometimes called yellowface) cockatiels have yellow cheek patches rather than orange ones. Only the orange patches are affected in this mutation, which comes in two forms: sex-linked and dominant. Dominant yellowcheek is inherited in the same way as dominant silver, although I have not heard that there is any visible difference between a single-factor and a double-factor dominant yellowcheek.