Refined methods for assessment of nutrient reserve use and regulation of clutch size

Methods for evaluating regulation of clutch size by endogenous nutrients have evolved rapidly over the last decade. Use of regression and correlation approaches to estimate rate of depletion of nutrient reserves and to test hypotheses about regulation of clutch size represented significant advances. Assessment of relationships between nutrient reserves and clutch size have been substantially improved by controlling for both body size and laying date. We point out potential biases and spurious correlations in current hypothesis tests, which examine the relationship between remaining nutrient reserves and remaining rapidly developing follicles. We recommend new methods to control for clutch size and for estimation of depletion of nutrient reserves, and for testing hypotheses regarding clutch size regulation.