Seen at the Denver Zoo, it’s an Inca Tern:
The Inca Tern is a fairly large tern, growing up to about 41 cm in length. Sadly, its numbers are no longer so large — about 150,000 now live along the Pacific coast of Peru and Chile, where millions once thrived. As a result, they have been declared Near Threatened, and islands with their breeding sites have been placed under protection.
In the wild, Inca Terns live and nest in huge colonies of thousands of birds, generally on rocky cliffs. They feed on anchovies and other small fish in the Humboldt Current. Inca Terns will also scavenge scraps from sea lions and dolphins, even being brazen enough to steal food from those neighbors’ teeth.