T4 and Amino Acid Metabolism Coordinate Feather Renewal in Humboldt Penguins

A research team mapped hormonal and metabolic changes during molting in captive male Humboldt penguins (Spheniscus humboldti). Thyroxine (T4) increased at molt onset and remained elevated until feather replacement ended, while coordinated shifts in amino acid metabolism may have supported keratin production. By linking endocrine signals with metabolic pathways, the study clarifies how penguins…