American Bittern

The colloquial nickname of “thunder pumper” is apt for the American Bittern. Not only is its territorial call loud and far carrying, but if you have the good fortune to see one in action the gyrations of its head and neck are a reasonable approximation of a pumping motion. These contortions serve to fill the bird’s esophagus with air, which is then released to create the characteristic call. Seeing a bittern, however, is easier said than done, since they tend to lurk in dense cattails and are most active at dawn and dusk. Their camouflaging plumage can make detection tricky too, more so if they assume a vertical position to blend in with marsh vegetation even more effectively. Of course, when they reflexively take this position in plain sight they tend to stand out a little better.

Although they will use salt marshes during migration and winter, bitterns nest almost exclusively in Marsh & Shrub Wetlands. These can vary greatly in size, including marshes less than an acre, and generally contain areas of dense emergent vegetation. Otherwise, the species is quite generalized in its habitat selection, even nesting occasionally in wet hayfields if they are near a more permanent wetland. The nest is constructed by piling dead marsh vegetation (e.g., cattails, rushes) into a mound above the water, and lining this with dry material. The 3-5 eggs are incubated for about a month and young leave the nest after 1 or 2 weeks, although they may remain dependent on the female for another month.

Because they are so secretive, we have limited information on the status of bitterns in New Hampshire. Data from the Breeding Bird Survey in the Northeast show a mix of slow increases, slow declines, stable populations, while observations submitted to eBird suggest a wider distribution than in the early 1980s. While they are almost certainly less common than before widespread alteration of New Hampshire’s wetlands, their ability to use small and isolated wetlands should serve them well for the foreseeable future.