After the ice sheet on Yellowstone Lake breaks up in May and grinds downstream beneath Fishing Bridge, cutthroat trout spawn in a frenzy, laying millions of eggs in the riverbed gravel within sight of the bridge. The spawning season powerfully affects other wildlife in the Fishing Bridge area as a variety of birds and animals are drawn to the feast. Ospreys dive for immature cutthroats less than 13 inches long, pelicans take adult fish, and grizzly bears snatch spawning trout while seeking seasonal protein.