Controlling for variation in breeding schedule (clutch initiation date), gender, and throat color, greater seasonal reproductive success is associated with positive carotenoid balance.

Results portrayed are from a mixed model of seasonal reproductive success as a function of changes in carotenoids between two successive sampling events, controlling for gender and feather color. Adjusted R-squared  = 0.52. Body mass is highly correlated with changes in carotenoid balance (Table 2) and thus was not included as a covariate in this test, to avoid problems of multicolinearity. Numerator degrees of freedom  = 1, ddf =  denominator degrees of freedom. N = 27 individuals.