By Annie Perry, MNA Intern
When I’m at my parents’ house in metro Detroit, one of my favorite sightings are the great blue herons that wade in the neighborhood’s ponds. Great blue herons can adapt to almost any wetland habitat in its range and can be found in heavily developed areas as long as they have bodies of water with fish. These large, majestic birds are not on Michigan’s endangered species—in fact, the populations in the state are large and healthy—but MNA works to protect great blue herons and their rookeries, which are being displaced by shoreline development and timber cutting.
The great blue heron is the largest heron in North America and can be recognized by its long legs; long, slender neck; and thick, dagger-like bill. Great blue herons appear blue-gray from a distance, but the upper-side of the wings are two-toned in flight and are pale on the forewing and darker on the flight feathers.
MNA protects the great blue heron because of its colonial nesting behavior and declining habitat. Construction of vacation homes, boating, sport fishing, camping, or hunting within or near active heronries are all sources of disturbance or direct habitat loss. These activities have caused some herons to abandon their breeding colonies or have led to reduced reproductive success.
Great blue herons build their nests in tree branches high off the ground using sticks, twigs, leaves, and other materials. These nests are refurbished and reused every year, making it important for MNA to protect the rookery.
Protection provided by MNA sanctuaries
Black River Nature Sanctuary protects 102 acres of floodplain and mesic southern forest and was donated to MNA in 1992 specifically to protect the heron rookery. One reason Black River is a Class C sanctuary—meaning guests must be authorized by the MNA office or a steward before visiting—is for the herons’ benefit. During 1993, when the sanctuary was open to visitation, Black River received a high volume of traffic from the general public. That year, there were numerous reports of disturbance to the rookery, as well as vandalism, camping, and disturbances to neighbors living near the sanctuary. As a result, unauthorized visitors are not permitted in the sanctuary in order to keep disturbances of the rookery to a minimum.
MNA recently acquired the Great Bear Swamp Nature Sanctuary, which is located near the Black River Nature Sanctuary. While Great Bear Swamp is a few miles from the rookery and does not protect it directly, protecting more land in that area will continue to benefit the many plant and animal species that live there.
For information on other MNA sanctuaries, visit the MNA website.