What is heron rookery?

Some articles on herons, heron rookery, rookery:

Indiana Dunes National Lakeshore - Natural Areas
... Coots Mallards Wood Ducks Kingfishers Tree Swallows Rusty Blackbirds Green Herons Beaver sedges Invasive Plants common reed hybrid cattail Reed canary grass Green Ash Cottonwood ... native plants, either as seed or small sprouts Removing non-native plants and trees Heron Rookery See also Heron Rookery The Heron Rookery is located along the East Arm Little ... The Rookery is physically separated from the main part of the park ...