Herons nest in colonies (colonial nesters) in mature trees in or near wetlands. Nesting birds tend to be very sensitive to human disturbance.
Great blue herons are large wading birds that nest in colonies of several to many pairs. Nesting colonies usually are found near wetland and shoreline feeding areas, though they occasionally will nest at some distance from wetland feeding areas. Most southern New Hampshire nests occur in dead trees in beaver ponds. North Country nests are usually in live white pines that tower above the surrounding treetops. Heron colonies also may occur in mature live hardwoods on upland sites. Heron colonies come and go over time; often as nesting snags fall and trees lose their branches or as a nearby food source changes.
Human activity in the vicinity of a nesting colony during the breeding season may lead to low productivity or abandonment; distance from human settlements appears to be a significant factor in colony site selection. Great blue herons will flush from nests in response to intrusions at distances of roughly 400 to 600 feet early in the breeding season (April through May) before incubation has begun, and at distances of roughly 100 to 300 feet during incubation and nestling periods.
Prevent disturbance or loss of heron nesting colonies.
4.2 Wetlands; 4.3 Forest Management in Riparian Areas; 6.8 Beaver-Created Openings.
Elliott, C.A. 1988. A Forester's Guide to Managing Wildlife Habitats in Maine. University of Maine Cooperative Extension, Orono, Maine.
Migratory Bird Act of 1918. http://www.fws.gov/laws/lawsdigest/migtrea.html Accessed on February 23, 2010.
N.H. Bird Records. http://www.nhbirdrecords.org Accessed on February 23, 2010.