Elegant Terns bring ocean contaminants inland to their island colony

Elegant Terns have been sighted 14 times since April hunting these waters, dispersing north from Isla Rasa where nearly the entire global population nests. The birds follow fish migrations — a sensible ecology — but the fish themselves carry a hidden cost. The hunting grounds here have been formally listed as impaired for more than two decades, and no cleanup effort has been completed.

This creates a direct pathway for contaminants to reach the colony. Elegant Terns are trophic foragers; they concentrate whatever toxins accumulate in the small fish they prey on. When they return to Isla Rasa to feed their chicks, those same contaminants arrive in the food the young birds consume. The colony's resilience depends entirely on the ocean remaining relatively clean—a condition that has not held for at least twenty years.