Across the Watershed - Winter 2001

As the great blue herons are about to return to the Great Swamp National Wildlife Refuge after a winter in the south, Refuge Operations Specialist Tarik Adams is gearing up for his annual census count.

The great blue, Adams says, is easily recognized as "gray-blue in color with long legs, a long foreneck streaked with black, and up to a seven-foot wingspan. Breeding adults have ornate plumes on the head, neck and back, while non-breeders and juveniles lack plumes."

Loners nine months of the year, adult herons pair up, usually with a new mate each year, in early spring after returning to their three rookeries, or breeding grounds, in Great Swamp. Nests are located at the tops of dead trees. Made of carefully arranged twigs, the nests form shallow platforms from two to four feet across. They are re-used from year to year.

One of the three rookeries is easily viewed from a Wildlife Refuge overlook, Adams points out. To get to the overlook, take White Bridge Road in Long Hill Township to Pleasant Plains Road. Turn onto Pleasant Plains Road, following the sign to the Wildlife Refuge headquarters. A parking lot overlooking the rookery, along with an exhibit area and permanently mounted binoculars, is located about a mile beyond the headquarters entrance.

At the overlook in early spring, "Look for males displaying at the nest with neck stretch and fluff, dancing behavior, and for pairs at the nest with crest raising and bill clappering," says Adams.

After several weeks of mating behavior, the female lays from one to five oval, pale blue-green eggs. Incubation takes another four weeks, during which both males and females take turns on the nest.

After the young begin hatching in late spring, Adams continues, "You can see males and females returning to the nest with food for the young: fish, frogs, snakes, and even small mammals. In late summer, the nestlings begin to leave their nests, learning to hunt and feed in the ponds and waterways in and around the swamp. Then, starting in September, most will leave for southern wintering grounds, to return here next year."

As Refuge Operations Specialist, Adams tracks the Great Swamp heron population each year, using binoculars to count every nestling. The population has been stable, at about 255 to 300, for around six years, he reports, with annual births of about 80 herons just about balancing the annual decline.

Why the focus on the heron here? "Herons occupy a very important place in the local ecosystem," Adams says, "because they help regulate populations of amphibians, small mammals, and fish, usually stalking their prey as they wade in ponds." A formidable predator itself, the heron is not threatened by many animals. "Its local breeding and feeding grounds, however, are continually threatened by a loss of suitable habitat" - a fact that makes Great Swamp all the more important in the continued survival of the great blues in this area.

Albert Bozulic was a Drew intern for the fall semester.

Home | Newsletters | Previous | Next