Moorhen females lay eggs of different size and â-carotene content

In birds, carotenoids deposited in the eggs can influence the progeny's prospects of survival. As a potentially limiting resource, carotenoids should be allocated optimally by the mother during egg production. The Moorhen Gallinula chloropus produces large clutches. We tested if females differ in their allocation of macronutrients (proteins and lipids) and the key micronutrient, β-carotene. To this end, we measured intra- and inter-clutch variability in egg size and contents. All parameters showed large inter-clutch differences and low intra-clutch variability. The total amount of β-carotene decreased in smaller eggs, indicating that females did not compensate for smaller egg size with a higher content of this micronutrient.