Temperatures were in the upper 50's on this sunny morning. We were on the Woodpeckers of Southern California birding trip (San Diego Bird Festival). We had stopped for a picnic lunch at Lake Cuyamaca and saw this female Brewer's Blackbird. This photograph shows a side view of the bird with leucistic patterning on its throat, cheek and malar areas. Leucism is the term used to describe the phenotype resulting from defects in pigment cell differentiation and/or migration from the neural crest to skin, hair or feathers during development. This results in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a subset are defective) having a lack of cells capable of making pigment. Leucism can cause the reduction in all types of pigment, not just melanin.