How do salt glands help seabirds drink salt water?

Seabirds possess specialized organs known as salt glands—often located above the eyes—that allow them to ingest seawater without suffering from dehydration or salt toxicity.12

While the avian kidney is limited in its ability to produce highly concentrated urine, these glands function far more efficiently to maintain osmoregulation. The glands extract sodium chloride from the bird's blood and excrete it as a concentrated brine solution. This fluid is then discharged through a duct into the nasal cavity and expelled from the nostrils, often accompanied by characteristic headshaking movements. This physiological adaptation is essential for marine species, enabling them to thrive in oceanic environments where fresh water is unavailable.132