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On the highest mountains in the Northeast, summer hikers
might hear an oddly beautiful song that seems to combine
harsh chattering with echoing flute-like trills. Those
lucky enough to spot the singer will see a dull brownish
bird a little smaller than an American Robin, skulking in
dense growth of balsam fir. This high-elevation environment
is home to the Bicknell’s Thrush, one of the rarest
birds in the United States and quite possibly the avian
species in this country most at risk from global climate
change.
As the climate warms, vegetation zones move up
mountain slopes, with hardwoods replacing conifers, the
composition of coniferous forests changing, and the tree
line rising. “The future doesn’t look good for Bicknell’s
Thrush,” Wellesley College ecologist Dr. Nicholas L.
Rodenhouse says. “It’s a bird of high-elevation forest in
the United States, and that forest is expected to basically
disappear with climate change.”
Rodenhouse headed a 2006 study that showed that
even under best-case scenarios of global warming, habitat
for Bicknell’s Thrush would be reduced at least 50
percent in the United States, and the species could disappear
as a breeder in New York and Vermont. Though
Bicknell’s Thrush nests at lower elevations in Canada, the
climate elevator offers no more stops for this bird in the
United States; it’s already on the top floor.
The Search for Solutions
Can anything be done
to help birds—and other
wildlife—survive climate
change? The Wilderness
Society has hired Dr. Peter
McKinley, an ecologist
and ornithologist, to help
answer that question. “We
should try to buy time,”
he says, “by identifying,
and then protecting, landscapes
that will change
more slowly and that have
high biological diversity.
That would at least present
the future with an
opportunity to reassemble
ecological systems.”
www.wilderness.org
McKinley points to
populations of Bicknell’s
Thrush that use small,
regenerating spruce
and fir farther down the
mountain in some parts
of their range in addition
to the alpine spruce and
fir predicted to disappear
under warmer conditions.
“Biological variability,
especially genetic variation,
is a wonderful thing,”
he says, “and maintaining
it as long as possible in
as many places as possible
is an important part
of the research program
we are building at The
The Rodenhouse study also looked at the Blackthroated
Blue Warbler, a small songbird that nests across
much of the northeastern United States and southeastern
Canada. Less demanding in its habitat requirements than
Bicknell’s Thrush, the warbler would seem to be safe for
now from serious climate-change threats.
But this warbler thrives best in areas where a mix of
hardwoods and understory shrubs provides high levels
of invertebrate prey. The Rodenhouse study showed that
a warmer climate would result in a loss of a significant
amount of prime habitat, leading to lower populations
over much of the warbler’s range. Black-throated Blue
Warbler was chosen for the study because it is considered
representative of the region’s birds, and after examining
various predictions for climate change, the report ominously
concluded: “[W]e are unaware of any scenarios in
which the effects of such interacting disturbances on the
biological communities of the Northeast will promote the
stability and viability of bird populations.”
Conservation planning for migratory birds must consider
more than just nesting ranges. “If you want to understand
how climate change might influence birds in the future, you
need to understand their exposure throughout the annual
cycle, whether it’s in the tropics, during migration, or on the
breeding grounds,” says Dr. Peter Marra, a scientist with the
Smithsonian Migratory Bird Center.
Wilderness Society.” We
have scientists tackling
this work from Maine,
where McKinley is based,
to Alaska.
In addition, we are leaders
in efforts to restore national
forests and other lands
damaged by industrial
activities such as logging.
Once restored, these
places can provide better
wildlife habitat and store
more climate-changing
carbon. Public education
is another high priority for
our climate team because
an aroused citizenry is
necessary to enact strong
laws and change behavior.
For example, we are
producing reports on the
best carbon-storing public
forests in each state.
Of course, the work we
have been doing every
day since 1935 to protect
land pays important dividends
by limiting climate
change and offering
plants and wildlife a better
chance to adapt. For
more on The Wilderness
Society’s effort, visit:
http://wilderness.org/campaigns/global-warming.
Among the many species of birds that may suffer as the climate changes are, clockwise from top left, Black-throated Blue Warbler,
Bicknell’s Thrush, Gray Jay, Common Loon, and young American Redstart.
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