Bitterns – common, but seldom seen


Drive past a marsh, lakeshore or river, you’re likely to see a stately great blue heron hunting in the shallows. They are common, impressive and widespread.

Though great blues often stand motionless as they scan the water for prey such as fish or crayfish, they also stand more than 4 feet tall on long skinny legs and have a long daggerlike bill. It’s a bird most people recognize as a member of the heron/egret family.

Other familiar members of this family include the all white great and snowy egrets, which patrol the same shallow areas that attract great blue herons, and the diminutive green heron, which skulks along shady streamside waterways.

Unlike many members of this family of birds, bitterns are secretive and often difficult to find. They prefer dense emergent aquatic vegetation such as cattails. Only when they wander to the edge of the vegetation do they become visible.

My best views of both American and least bitterns have come from boardwalks at marshes in parks and refuges in Pennsylvania, New Jersey, Delaware and Florida. Boardwalks provide easy access to wet and muddy areas where secretive marsh birds reside.

Both American and least bitterns have cryptic streaky underparts. When alarmed they may dash into the dense marsh vegetation. Sometimes they stay close to the edge where they “freeze” and throw their bill upward. Thanks to their streaky camouflage, they virtually disappear into the vegetation. It reminds me of the ballplayers fading into the cornfield in “Field of Dreams.”

Because least bitterns are so small (more about that later), they can use another technique to make their way through dense vegetation. They can literally walk from stalk to stalk by using their long toes to grasp stems of cattails and reeds.

A frightened bittern may also burrow into denser vegetation or make short seemingly weak escape flights. That both species are strong migrants indicates that they are better fliers than their escape behavior suggests.

Though the voices of most herons and egrets are harsh grunts and croaks, bitterns make distinctive sounds. The American bittern is sometimes called a “thunder-pumper.” The sound is a gulping, guttural “Unk-a-chunk,” which can be repeated many times. The least bittern makes a series of cooing notes, reminiscent of mourning doves or black-billed cuckoos.

The most interesting aspect of comparative heron biology is their size. The great blue is huge. It weighs in at more than 5 pounds and stands almost 5 feet tall. When seen alone, great egrets seem equally large, but it’s an illusion. Great egrets weigh less than 2 pounds and stand just 39 inches tall. Seen side by side, the size difference is obvious.

Snowy egrets, which can be quite common at coastal salt marshes, weigh just 13 ounces and are less than 2 feet tall. And green herons, which fish inconspicuously along wooded waterways, weigh in at 7 ounces and stand just 18 inches tall.

At 1.5 pounds, American bitterns are chunky birds measuring about 28 inches tall. In comparison to other herons, least bitterns are surprisingly tiny. They weigh about 2.8 ounces, stand 13 inches tall and have a wingspan of 17 inches. That’s about the size of a robin and just a bit smaller than a blue jay. They certainly have never impressed me as songbird-sized anytime I’ve seen one.

Regardless of size, however, bitterns are voracious predators. American bitterns eat fish, insects, crayfish, crabs, frogs, snakes and even small mammals such as meadow voles. Least bitterns eat the same kinds of foods and occasionally take eggs and chicks from nests of marsh-nesting songbirds.

As summer winds down, keep your ears peeled for the sounds of bitterns anytime you pass a cattail marsh. The voice of the “thunder-pumper” is as distinctive as a turkey gobble. And if you think you hear a mourning dove cooing from the middle of a marsh, watch and listen carefully. It just might be an elusive least bittern.

Dr. Shalaway can be heard on “Birds & Nature” from 3 to 4 p.m. Sundays on 620 KHB Radio, Pittsburgh or live online at www.khbradio.com. Visit Scott’s website www.drshalaway.com or contact him directly at sshalaway@aol.com or 2222 Fish Ridge Road, Cameron, WV 26033