The Heath Hen (Tympanuchus cupido cupido) was a distinctive subspecies of the Greater Prairie Chicken, Tympanuchus cupido, a large North American bird in the grouse family, or possibly a distinct species.
Heath Hens lived in the scrubby heathland barrens of coastal New England, from southernmost New Hampshire to northern Virginia in historical times, but possibly south to Florida prehistorically. The prairie chickens, on the other hand, inhabited prairies from Texas north to Indiana and the Dakotas, and in earlier times in mid-southern Canada.
Heath Hens were extremely common in their habitat during Colonial times, but being a gallinaceous bird, they were hunted by settlers extensively for food. In fact, many have speculated that the Pilgrims' first Thanksgiving dinner featured Heath Hens and not wild turkey. By the late 18th century, the heath hen had a reputation as poor man's food for being so cheap and plentiful; Thomas L. Winthrop related that they could be found on the Boston Common and that servants would sometimes bargain with a new employer for not being given Heath Hen for food more often than 2 or 3 days a week.
Very similar to the Greater Prairie Chicken of the Great Plains, but slightly smaller (Pearson, 1917). Length of the bird was approximately 17 inches (43 cm) and weight was about two pounds (900 gm). A specimen weighing three pounds was claimed by Alexander Wilson but that figure was not verified by later ornithologists (Pearson, 1917, Forbush, 1927). Several key plumage characteristics separated the Heath hens from their Great Plains counterparts. Heath hens were generally a strong reddish hue in their plumage, especially in their crop area, and much thicker barring throughout the breast and sides. Their pinnae (horns) were generally pointed, and tails were a greyish-brown.
These were protected by a hunting ban and the 1908 establishment of the "Heath Hen Reserve" (today the Manuel F. Correllus State Forest) and the population rapidly grew to almost 2000; by the mid-1910s, observing the birds on their lekking grounds had become something of a tourist attraction. However, a destructive fire during the 1916 nesting season, severe winters, inbreeding, an excess number of male individuals and apparently an epidemic of blackhead disease which might have been transmitted by poultry brought the numbers down quickly; after a last recovery to 600 in 1920, the population began its final decline.
In 1927, only about a dozen were left - a mere two being females - despite being afforded the best protection according to contemporary science, and that number had declined to a handful, all males, by the end of the year. After December 8, 1928, apparently only one male survived (Gross, 1931), lovingly nicknamed "Booming Ben". He was last seen on his traditional lekking ground between West Tisbury and today's Martha's Vineyard Airport on March 11, 1932 - early in the breeding season -, and thus presumably died, about 8 years old, days or only hours afterwards from unknown causes.
Heath Hens were one of the first bird species that Americans tried to save from extinction. As early as 1791, a bill "for the preservation of heath-hen and other game" was introduced in the New York legislature. Although the effort to save the Heath Hen from extinction was ultimately unsuccessful, it paved the way for conservation of other species. Ironically, the establishment of the reserve on the open shrubland of what was then called the Great Plain may have accelerated the Heath Hen's extinction. Fires were a normal part of the environment, but with the attempt to suppress fires instead of enforcing ecological succession with controlled burns, habitat quality decreased and undergrowth accumulated until a normally limited fire would have disastrous consequences as it did in 1916.
Realizing the degradation that has affected the State Forest (and although it does hold remarkable biodiversity, prevents it from being utilized to its full potential), reestablishment of the original shrubland/heath/woods mosaic and eventual reintroduction of Greater Prairie Chickens as an "umbrella species" that serves as an indicator of good habitat quality is being discussed since the late 1990s.
However, Johnson & Dunn caution against reading too much into these results: while the Lesser Prairie Chicken is considered a distinct species and the genetically apparently equally distinct Heath Hen would thus likewise deserve species status, mtDNA haplotypes in small populations that have undergone bottlenecks are likely to show higher divergence than they would judging from taxonomic status alone (Johnson et al., 2003; see also genetic drift). Thus, given the fact that all Heath Hen specimens from known localities studied by Johnson & Dunn are Martha's Vineyard birds - where the population may never have exceeded several thousand due to the limited space and genetic exchange with the mainland was limited -, it is possible that the low genetic diversity and apparent distinctness of the Heath Hen are an artifact of the small number of useful specimens, all from the same, closely-knit population.
Prairie chickens were indiscriminately introduced to the Eastern Seaboard after the Heath Hen was gone from the mainland, but failed to thrive. There exists a considerable number of supposed Heath Hen specimens in public collections today, but many - all mainland specimens and those with insufficient locality information - cannot be unequivocally assumed to be Heath Hens. For example, a mere 7 unequivocal Heath Hen eggs - equivalent to a very small clutch (Luther, 1996) - are known to be held in public collections today. That the genus Tympanuchus apparently evolved rapidly and therefore has high morphological but low genetic distinctness between taxa further complicates research.
It is also important to note that while introductions of the Greater Prairie Chicken (Tympanuchus cupido pinnatus) were occurring, true Heath hens (Tympanuchus cupido cupido) are distinct enough in morphological features to be separated from the Greater Prairie Chicken. Giving a generous starting date of ~1810 when introductions could have started, taking into account that Lewis and Clark did not even return from their expedition until 1806, it gives roughly a 60 year period of introduction. From an evolutionary biology aspect, in a 60, or even 100 year timeframe, a species like the Greater Prairie Chicken would not have been able to evolve to the point where he would so closely resemble the native Heath Hen that he could not be distinguished.
A prime example of this would be the Lesser Prairie Chicken (Tympanuchus pallidicinctus) that differs from his Greater "cousin" in being smaller, lighter, and having less distinct barring. Opposed to the Heath hen that was smaller, darker, and had more distinct barring. Meaning that the Lesser Prairie Chicken can be readily distinguished from the Greater Prairie Chicken both morphologically and genetically (much like the Heath hen) even if he were found in an area where the Greater Prairie Chicken inhabited. The apparent distinctness and the failure of the early introductions raises the question of whether the Heath Hen was uniquely (by comparison with its relatives) adapted to the more oceanic climate of its former area of occurrence, and in consequence, whether a future attempt to establish a population of the western birds on Martha's Vineyard could be bound to fail, possibly even by competing for funding and other resources jeopardizing the extant but much declined populations of the prairie chickens. Clearly, more research is necessary, for example by analyzing mainland specimens to determine whether they can be assigned to a taxon from molecular and morphological characters.