A California Towhee with plumage lacking melanin pigment, a condition called Leucism. California Towees are normaly an overall matte brown color and do not have any white coloration.

Leucistic birds have plumage that lacks melanin pigment due to the cells responsible for melanin production being absent. This results in a white feathers, unless the normal plumage colour also comprises carotenoids (e.g. yellows), which remain unaffected by the condition. Although leucism is inherited, the extent and positioning of the white colouration can vary between adults and their young, and can also skip generations if leucistic genes are recessive.

The reduction of pigment in leucistic birds causes feathers to weaken and be more prone to wear. In some situations this can hinder flight, which, in addition to leucistic birds usually being more conspicuous, can heighten risk of predation. There is also evidence that leucistic birds might, on occasion, not be recognised or accepted by a potential mate.

California TowheeLeucistic bird