Saks, L., McGraw, K. J. & Hõrak, P. (2003) How feather colour reflects its carotenoid content. Functional Ecology 17, 555–561.

Equation 2 (p. 557) in Saks et al. (2003) describing the calculation of chroma was erroneously presented. The value of chroma was calculated according to Endler (1990) and the correct presentation of this calculation should be as follows:

image(eqn 2)

where B = (Qb/Qt), G = (Qg/Qt), Y = (Qy/Qt), R = (Qr/Qt).

Unfortunately, the erroneous version of this equation has also been reprinted in Montgomerie (2006).