Seasonal changes in parental hormone levels and their association with mercury contamination in a tropical seabird.

Seasonal prolactin levels in magnificent frigatebirds peak during incubation and decline during chick-rearing, with no negative association with mercury contamination observed.

• Why it matters: Understanding how environmental contaminants like mercury affect hormonal regulation of parental care is crucial for wildlife conservation, especially in tropical ecosystems where contamination levels are rising.
• What they did: The study measured prolactin levels across different breeding stages in Fregata magnificens in French Guiana and analyzed their relationship with mercury concentrations in the birds, involving both sexes and various breeding stages.
• The result: Prolactin levels followed expected seasonal patterns and were not negatively linked to mercury exposure, suggesting that at observed contamination levels, mercury does not impair prolactin regulation in this species.