Great Blue Heron
Scientific Name: Egretta thula
Classification: Nongame
Abundance: Found statewide
The great blue heron is the largest heron in North America and one of North Carolina’s most familiar and frequently seen wading birds. Often called a “crane,” it is common around shores of open water and in wetlands where it stands silently or walks very slowly waiting for prey to get close enough so it can spear it with a rapid thrust of its bill. The great white heron (Ardea herodias occidentalis), a subspecies of the great blue heron, has been seen across the state on several occasions.
As one of the largest herons in the world, the great blue heron stands more than 3 feet high as an adult and weighs approximately 5 ½ pounds. Its wingspan covers nearly 6 ½ feet. It has a slate blue body and wings, long, dark-to-yellowish legs and a long, pointed yellow bill, which is uses for catching fish. Adult great blue herons have a white head with a black stripe above each eye that extends down the plumes of the back of the head. Juvenile birds have gray heads and do not have plumes. Plumes will grow as they become adults.
Great blue herons live in both freshwater and saltwater habitats, including marshes, swamps, shores, rivers and tidal flats. They don’t generally nest in estuaries or saltwater environments. They forage in calm waters or slow-moving rivers where they feed on almost anything that comes within striking distance of its long, pointed bill. They typically feed in shallow waters. Because of their large size, great blue herons can feed in deeper waters where other birds cannot reach. Favorite prey include fish, amphibians, reptiles, small mammals, insects and other birds. They grab their prey in their strong mandibles or use their bills to impale larger fish, often shaking them to break or relax the spines before gulping them down.
The Great Blue Heron is a nongame bird species with no open hunting season.
Management
The N.C. Wildlife Resources Commission (NCWRC) completed the most thorough survey of great blue heron nesting colonies within Piedmont and Upper Coastal Plain regions in 2012, and detected more than 7,680 nests in 518 colonies (Schweitzer, NCWRC, unpublished report). Aerial surveys of North Carolina’s heronries are extensive and only conducted every ten years. The NCWRC continuously updates its colonial waterbird database with reports of active nesting colonies of great blue herons from partner agencies and researchers.
These data are used to provide guidance to project managers so buffers are maintained between projects and colonies of nesting great blue herons. Loss of nesting trees and human activities adjacent to colonies are causes of nest failure and abandonment of sites by great blue herons. Colonies in trees within swamps or on islands include a water buffer between nest trees and human activities, and are optimal sites. During the nesting season, keeping foot traffic ≥100 m from the colony will enhance nesting success and reduce the probability of abandonment.
Great blue herons are adaptable and tolerant of people’s presence ≥50 m from them while foraging, and are often seen near homes and businesses, feeding in ponds, drainage ditches, and waterway shorelines. In fact, they have become savvy to people’s small and large aquaculture operations, sometimes eating koi and other fish. Mesh netting over ponds and dogs which chase herons are methods used to protect aquaculture facilities. Before any management of great blue herons is implemented, the NCWRC or the U.S. Fish and Wildlife Service must be consulted due to the protected status of the species.
