Herons use dry twigs to build their sloppy nests. A rookery might have a few nests or as many as 200 nests. Different species build their nests at different heights, from ground level to 160 feet in the air. Herons nest in big groups for a good reason - a lot more eyes watching out for predators. By building their nesting colonies near marshes, lakes, and streams, often on islands, the birds can stay away from predators such as snakes, raccoons, and foxes.
Crows still can raid the nests.
Because the parent birds might leave their nests if people bother them, some rookeries on state land are not open to people from May 15 through July 15. The largest of North America s 12 heron species, the great blue heron stands almost 4 feet tall. This adaptable bird lives throughout Minnesota. The southern and central parts of the state have the largest rookeries. Great blue herons often choose the highest treetops for their nests.