How
Man Effects Birds
From: Andy
Soos, ENN.com
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| This tufted titmouse regularly watches me work through my window |
Can
man and bird live side by side? If not, how far apart should they be. Are some
friendlier than others? According to a study by the Wildlife Conservation
Society (WCS), impacts to bird communities from a single rural, exurban
residence can extend up to 200 meters into the surrounding forest.
The study
also determined that sensitive bird species such as the hermit thrush and
scarlet tanager prefer unbroken forests with no houses. Others, like the blue
jay and black-capped chickadee, seem to like having, and often thrive with,
human neighbors.
The
Blue Jay is one of the commonly known human friendlies and is is resident
through most of eastern and central United States and southern Canada. It
breeds in both deciduous and coniferous forests, and is common near and in
residential areas. It is predominately blue with a white chest and underparts,
and a blue crest.
The
Adirondack Mountains are contained within the 6.1 million acres of the
Adirondack Park, which includes a constitutionally protected Forest Preserve of
approximately 2,300,000 acres. About 43% of the land is owned by the state,
with 57% private in holdings, heavily regulated by the Adirondack Park Agency.
The Adirondack Park contains thousands of streams, brooks and lakes, most
famously Lake Placid.
The
report appears in the current online edition of the Journal of Landscape and
Urban Planning. Authors of the study are Drs. Michale Glennon and Heidi Kretser
of the Wildlife Conservation Society.
Rural
exurban development is residential development existing outside of cities and
towns, and is generally characterized by larger lot sizes (5-40 acres or more)
and lower density than suburban development. Exurban residences exist within an
otherwise unaltered ecosystem.
Exurban
homes change the environment by bringing vehicles, noise, lights, pets, people,
and food sources into the forest, as well as by physically altering and
fragmenting habitat. These changes can have myriad impacts, including altered
species behavior and composition, increased human wildlife conflicts, new
predator-prey dynamics, and decreased biotic integrity.
Biological
integrity is associated with how pristine an environment is and its function
relative to the potential or original state of an ecosystem before human
alterations were imposed. the accepted definition is "the capability
of supporting and maintaining a balanced, integrated, adaptive community of
organisms having a species composition, diversity, and functional organization
comparable to that of the natural habitat of the region."
The implications
of this definition are that living systems have a variety of scales relative to
which they exist, that one can quantify the parts that sustain or contribute to
a system's functioning and that all systems must be seen in the context of
their environments and evolutionary history.
"Adirondackers
take great pride in their surroundings and try not to unduly disturb the
natural setting in which they live," said WCS Adirondack Program Science
Director Michale Glennon.
"A
key finding of the study is that the ecological footprint of development can be
much larger than its physical footprint. We found that even a small home and
lawn can change bird communities some 200 meters away, which means more than 30
acres of the surrounding landscape, depending on what types of activities are
occurring on the residential property. It is important that we learn how birds
and other wildlife react to particular kinds of human activities, and find ways
to minimize the negative impacts for wildlife in exurban areas."
The
study found that species sensitive to human impacts include the black-throated
blue warbler, black-throated green warbler, hairy woodpecker, hermit thrush,
ovenbird, scarlet tanager and the winter wren. The presence of some species,
like the scarlet tanager (adult males are bright red with black wings and tail
while females are yellowish on the underparts and olive on top) are a good
indicator of undisturbed forest health.
The
study was modeled after one conducted in a shrub-oak ecosystem in Colorado
where scientists calculated a 180-meter ecological effect zone based on their
results. Glennon and Kretser believe that the similar results in two different
ecosystem types may indicate that human behaviors associated with exurban homes
play a larger role in shaping avian community characteristics nearby than do
habitat alterations created by construction and clearing.
While
breeding bird communities were used to measure the impacts of exurban
development in the study, the authors note that birds can serve as valuable
indicators of overall biodiversity.
For
further information see Birds and Man.
