Geoscience Reference
In-Depth Information
from Alaska to Newfoundland. More than a century later,
DNA
analysis demonstrated conclusively that it was
a separate species, and in 1995 it became North America's newest bird—Bicknell's thrush. Its seeming obscur-
ity relates in part to the remoteness of its preferred nesting sites, on offshore islands and on the virtual islands
of the highest peaks of the Appalachians. It is the only native breeding bird from the northeastern United
States and Maritime Canada and is documented as nesting in the Christmas Mountains of northern New Brun-
swick, and the Cape Breton Highlands, and on Mount Mansfield in Vermont.
Bicknell's thrush
Bicknell's thrush prefers dense nesting habitat in the subalpine spruce-fir zone just below the tree line,
where high winds have stunted and shaped evergreens to form an almost impenetrable tangle—the krummholz
effect. It is also found in the “fog forest” of stunted spruce along the coast, often with blackpoll warbler and
fox sparrow. Because of its secretive character, fog-shrouded habitat, and well-concealed nests, it often has to
be identified by its spiraling song, which one 19th-century observer praised as “a most ethereal sound, at the
very top of the scale, but faint and sweet.” Although it faces some threats to its “sky islands” in New England
and in the adjacent Canadian provinces, its major challenge is on its Caribbean island wintering grounds,
which include Hispaniola, Puerto Rico, and Jamaica. Only 13 percent of native forests still stand in the Domin-
ican Republic and less than 5 percent in Haiti.
ATLANTIC COASTAL PLAIN FLORA
A GROUP
of nearly fifty plants known as the Atlantic coastal plain flora are found in southwestern Nova Scotia,
where they were first discovered in the 1920s by preeminent Harvard botanist M.L. Fernald. Most of these
plants are characteristic of various wetland and heathland types of the eastern United States, where the ranges
of some of these species extend northward only to New Jersey or to Cape Cod. Until recently, it was thought
that these plants persisted during the last glaciation in a refugium off the Atlantic coast, when the sea level was
