Dr. Cheryl F. Harding is a researcher in the Hunter College Department of Psychology notes the importance of color in Zebra Finches used in birdsong research.
In one study, the wild-type gray zebra finch did well, while other colors did not. Dr. Harding states that “It has been shown for rats that the fawn-hooded rats (light brown and white instead of black and white) have a very different serotonin system. We never looked into whether that was the problem with tan finches, but it seems possible. In addition, white birds’ visual connections are quite different from those of grays. So when you use multi-colored finches in your studies, you are adding a lot of variability. . . . In addition, we saw many behavioral differences between males with different plumage colors. In the end, we only used grays.”