American lentiginosus

Although rarely seen, the American Bittern is one of the best known North American marshbirds. The is widely known for its habit of trying to elude detection by freezing in position with its head and neck pointed skyward; observers have even seen swaying from side to side to match the movement of the windswept marsh grass. Its "pump-handle" territorial song charac­ terizes marshes throughout its range, which extends from coast to coast across the middle states and north to Hudson Bay. Although freshwater marshes are its preferred haunts, the species is flexible in its choice of nest sites and will even accept dense, grassy up­ frequently connects the nest site with plat­ land fields provided water is nearby. Spear forms constructed by the birds. Although (1976) mentioned that wet fields were used their function has not been documented, it for feeding by American in Ver­ is interesting to note that similar structures mont. American Bitterns return early to Ver­ are built by other, unrelated marsh nesters mont's marshes, frequently appearing the (e.g., Pied-billed Grebes, Black Terns, and third week of April. By early May, the "pile­ Common Moorhens), who use them for driver" call of the males can be heard at resting and brooding of the young. The fe­ dusk near many of the state's wetlands. The male lays 3 to 5 olive-buff eggs, commenc­ males appear to be territorial throughout ing incubation with the initiation of the the breeding season, and some evidence clutch. Consequently, the length of the in­ suggests that they may be polygynous cubation period is dependent on the number (Palmer 1962). of eggs in the clutch, each egg requiring 24 Males may also "pump" while on spring days to hatch. Vermont egg dates range from migration; caution is advised before con­ May 21 to June 18 (three records). Al­ cluding that a heard early in the breed­ though the male remains in the vicinity, he ing season is on territory. While intraspe­ apparently does not assist in either incu­ cific aggression has not been documented, bating or caring for the young. He may males frequently call in response to Yellow continue to call throughout the breeding and Virginia Rail and Sora calls. Courtship season, presumably seeking to lure new fe­ behavior, though not well known, includes males to his territory. The young are fed by aerial and ground chases and a slow stalk regurgitation at the nest for about 2 weeks, by the male, who moves forward in a "retch­ and remain dependent on the parent for an ing" position while holding the white nup­ undetermined period of time thereafter. Age tial plumes on his shoulders erect (Johns­ at first flight is also unknown. Reports of gard 1980). fledged young in Vermont range from June Nesting invariably occurs on the ground, 30 to July 25 (three reports). although a myriad of sites may be accepted. American Bitterns feed by waiting for Cattail stands, islands, and even dry fields or slowly stalking their prey through the may be used. The nest, apparently con­ marsh. Virtually any form of life structed by the female, is a haphazard struc­ small enough to be swallowed is taken. Di­ ture, sometimes little more than a scrape, etary staples include , , in­ always in dense vegetation. A series of paths sects, rodents, amphibians, and reptiles, all

34 Species Confirmed as Breeders in Vermont ,,' 72'

No. of priority blocks in which recorded TOTAL 42 (23%) Possible breeding: 25 (59% of total) Probable breeding: IO (24 % of total) Confirmed breeding: 7 (I7% of total)

Physiographic regions in which recorded % of % of species' no. of region's total priority priority priority blocks blocks blocks

Champlain Lowlands I4 45 33 CD Green Mountains 9 I7 2I o North Central 5 26 I2 Northeast Highlands 2 I2 5 10 '0 .0 East Central I6 o I I I .,. 7 Taconic Mountains 2 I2 5 10 20 '0 I I I Eastern Foothills 7 29 I7

,,' 72' of which are usually swallowed on the spot the state affirm this species' ability to oc­ and brought to the nest to be regurgitated cupy small wetlands. The Taconic Moun­ to the young partly digested. Although more tains, North and East Central regions, and active at low light intensities, birds may for­ Northeast Highlands had the fewest sight­ age throughout the day and night. ings, because of a paucity of wetlands. Extra The American Bittern was considered a effort is required to locate this marsh deni­ fairly common summer resident in Ver­ zen, which is extremely difficult to confirm mont's marshlands by Perkins and Howe because of its stealth and its practice of (1901), who wrote that it nested in "meadow swallowing food before taking it to the and swampy land." Fortner et al. (1933) young, and because nests are hidden in in­ noted that American Bitterns were "uncom­ hospitable cover. mon to rare summer residents." While the DOUGLAS P. KIBBE majority of sightings during the Atlas Proj­ ect came from the Champlain Lowlands, where most of the large marshes are located, a scattering of sightings from throughout

American Bittern 35