Blue–green distinction in language being described. For example, "blue" and "green" might be distinguished, but a single term might be used for both if the color is dark. Furthermore, green might be associated with yellow, and blue with black or gray. According to Brent Berlin and Paul Kay's 1969 study "", distinct terms for brown, purple, pink, orange and grey will not emerge in a language until the language has made a distinction between green and blue. In their account of the development of color terms the first terms to emerge are those for white/black (or light/dark), red and green/yellow. The word for blue
Yellow-collared lovebird lightening of the darker feathers, most noticeable in the wings, and face. It was first noted from Green (Wild) coloured parents, & originally called ""Yellow"". This new colour was soon built up in numbers by passionate aviculturelists, and once secure was bred to Blue coloured birds. The result was then known as ""White"", but we now call this combo a Dilute Blue. Yellow-collared lovebird The yellow-collared lovebird ("Agapornis personatus"), also called masked lovebird or eye ring lovebird, is a monotypic species of bird of the lovebird genus in the parrot family Psittaculidae. They are native to northeast Tanzania and have