Juan F. Masello never intended to study wild parrots. Twenty years ago, as a graduate student visiting the northernmost province of Patagonia in Argentina, he planned to write his dissertation on colony formation among seabirds.

But when he asked around for flocks of, say, cormorants or storm petrels, a park warden told him he was out of luck.

“He said, ‘This is the only part of Patagonia with no seabird colonies,’” recalled Dr. Masello, a principal investigator in animal ecology and systematics at Justus Liebig University in Germany. Might the young scientist be interested in seeing a large colony of parrots instead?

The sight that greeted Dr. Masello was “amazing” and “incredible,” he said. “It was almost beyond words.”