“Stop the car and back up!” my wife, Edie, exclaimed. “I think I saw something in the pasture.” The wet pasture, by a sluggish little stream, contained numerous clumps of tall wetland grass. Suddenly an American bittern (Botaurus lentiginosus) stood up and uttered its strange mating call, often described as ploonk ka doonk or oong ka chunk, which has given it the colloquial names of marsh pump or thunder-pumper. Indeed, this call does sound somewhat like an old-fashioned, long-handled pump. To me, however, it sounds most like someone dropping a couple of rocks into deep water some distance away.
After calling, the bittern dropped out of sight among the clumps of grass and moved a few steps. Then it rose and called again. This sequence was repeated over and over for a half-hour. We had previously heard bitterns call, but at a much greater distance. However, with the combination of the bird’s proximity and the use of binoculars, we were able to observe things that we had never seen or heard before.
When the bittern prepared to call, it pointed its beak upward, while its throat swelled alarmingly. Then, after uttering the first syllable, it dropped its head and produced the second syllable. At close range, what had always sounded at a distance more or less like ka instead proved to be a rather watery, gulping gurgle, somewhat akin to a person beginning to gargle. Thus at close range this middle syllable could best be described as something like gluggle. That was followed by the third syllable, as loud or louder than the first, but pitched slightly lower, making the entire call ploonk gluggle doonk. We remained entranced by the whole performance until, finally, cows wandered down toward the brook and the bittern flew off downstream.
This pumping call is the male bittern’s method of advertising for a mate. It’s heard through May and June, with the later calls probably emanating from males that haven’t yet located a mate. It’s a strange and unforgettable sound.
But the bittern also has another call that has given it the colloquial name of “stakedriver.” This resounding tok-tok-tok, which I’ve personally witnessed, sounds remarkably like a stake being driven by a maul or large wooden mallet. Although not given as often as the pumping call, this strange sound is heard from time to time emerging from the bittern’s marshy habitat.
At any rate, the bittern’s two distinct calls seem to have engendered some confusion among the writers of field guides. These guides usually refer only to the marsh pump vocalization but then sometimes say that it sounds like driving a stake. This can only be the result of repeating someone’s initially confused error, for the ploonk ka doonk call sounds nothing whatsoever like a stake being driven into the ground. This misinformation deserves to be corrected, for it can only bewilder the uninitiated. Regardless of any confusion, however, the bittern remains one of our most interesting – and in some ways mysterious – birds.