Fig 1. Relationship between PC2 and the probability of an adult fledging at least one young.

PC2 is an axis of variation in individual condition indices (packed cell volume, hemoglobin, scaled mass, muscle score, fat score) with those having high energy reserves and high oxygen carrying capacity on the positive end of the axis, and those having low energy reserves and low oxygen carrying capacity on the negative end of the axis. Breeding stages refer to the stage of the adult when he/she was sampled for condition indices (pre-breeding, egg-laying, incubating, and nestling stages).