Mate choice and reproductive success in the red-legged partridge (Alectoris rufa).

Behavioral patterns, reproductive success, and concentrations of plasma-luteinizing hormone, testosterone, and estrogen were compared in pairs of red-legged partridges which had either selected their own mates or had been randomly paired. Males in self-selected pairs called more frequently than males in non-self-selected pairs. Females in self-selected pairs but not those in non-self-selected pairs guarded their nests. Females in self-selected pairs had a greater egg production and laid more of their eggs in nests than females in non-self-selected pairs. There was a significant difference between the two groups in the concentration of plasma testosterone in males, which was higher in males from self-selected pairs prior to the onset of egg laying. These results are consistent with the hypothesis that mate choice affects both reproductive parameters and nest defense in monogamous birds.