Collision Course
Flight is a magnificent means of
transportation, allowing bats, insects,
birds and even humans to travel great
distances. For many birds, however, a
journey across the skies may be a
veritable obstacle course of human-related
hazards. International
Migratory Bird Day (IMBD) is an
opportunity to examine the obstacles
birds may encounter in flight and
explore the many ways we may
minimize their impacts.
The towers erected for our cell phones
and pagers, the lines that bring us power,
our vehicles, the windows on homes and
office buildings, and even sources of
renewable energy, such as wind turbines,
create obstacles for birds in flight.
Collisions with these obstacles may cause
the death of one bird or tens of
thousands of birds in a single incident.
Biologists estimate the combined
death toll from aerial collisions may
exceed 700 million birds each year and
affects all types, from ducks, gulls,
plovers, owls, and hawks, to wood-peckers,
hummingbirds, warblers,
sparrows, and finches.
The problem is urgent, and biologists,
conservation organizations, communi-ties
and individuals are joining forces
with industry representatives to
unravel the causes of bird collisions
and to explore ways of making a bird’s
journey safer. Individual participation
in these efforts can have significant
results. Small changes at home,
involvement at work, and active
contribution to your community can
make a world of difference to bird
conservation.
Clear the Way for Birds!
IMBD Explores Bird Collisions
International
Migratory Bird
Day (IMBD),
held annually
on the second
Saturday in
May, is an
invitation to
celebrate and
support
migratory bird
conservation.
IMBD Information
web - http://birds.fws.gov/imbd
phone - 703 /358-2318
IMBD Materials
web - http://www.BirdDay.org
phone - 1-866/334-3330
March 2005
Power Lines
Birds with large wingspans, such as raptors,
cranes, and swans, are less maneuverable
and thus most vulnerable to collisions with
power lines. The impacts may be especially
high when power lines are located near
marshes, lakes, and other habitats where
birds congregate in winter, when breeding,
or on migration. Wind and stormy weather
also make avoiding lines a challenge. New
guidelines that are used by utility compa-nies
are helping to lower the impact of
power lines on birds.
Solutions ~ Burying power lines eliminates
bird collisions. Flags or marker balls on
lines located above ground help to increase
their visibility, helping birds to see and avoid
them. When lines are parallel, the likelihood
that birds will see one line and avoid it only
to hit another are decreased.
In the IMBD 2005 artwork, David Sibley portrays collision
hazards using an illusion of depth and layers: a selection of birds
risks striking a plate glass window, in which is mirrored an array
of other birds against a crowded skyline of aerial obstacles.
Communication Towers
Communication towers provide coverage
for cell phones, pagers, television and radio
— technologies that are central to our
lives. Over 140,000 towers are located in the
United States, and as many as 5,000 new
towers are erected each year. Bird colli-sions
at towers have been reported for over
50 years, and studies are ongoing to
determine the causes and solutions. The
towers that are the most hazardous to
birds are those that are over 200 feet, are
illuminated at night with red lights,
are supported by guy wires, and are
located in migration corridors, near
wetlands and in areas prone to fog, low
clouds, and precipitation. Birds that
migrate at night are drawn to tower lights,
especially in poor weather. Disoriented,
they circle the area, eventually striking the
guy wires, the tower, or even one another.
Solutions ~ Birds are less likely to be
harmed by shorter structures that do not
require lighting or guy wires, lights that
are white or green, and towers that are
located away
from migration corridors and cloudy areas.
Creative placement of new towers includes
using existing buildings.
Wind Turbines
Harnessing the wind’s energy is an
economical means of producing electricity.
As early as 200 B.C., windmills were used
to pump water and grind grain. Today, wind
farms may include hundreds of turbines,
tall structures which support fan-like
rotors connected to generators. The
electricity produced by the spinning rotors
supplies power to towns and cities. Like
communication towers, turbines are most
harmful to migrating birds on cloudy
nights and when turbine height requires
the use of lights. Because turbines are not
supported by guy wires and rarely involve
lights, their impact on birds in flight
compared to other structures
is relatively low.
Solutions ~ Proposals for new wind farms
that consider bird migration routes, bird
abundance, and turbine height will help to
minimize fatalities.
Plate Glass
One of the greatest hazards to birds is
plate glass, with windows in homes and
offices killing as many as one billion birds
each year. Glass is invisible to birds, and if
it reflects the images of trees, bushes, the
sky or other natural habitat, a bird may fly
directly into it. The presence of house-plants
behind windows, the distance of
vegetation or bird feeders from windows,
and the angle of reflection may all influence
the likelihood of a bird flying into glass.
Studies indicate that one of every two
strikes is fatal. If not killed outright, birds
stunned after striking glass often fall prey
to hawks, dogs, cats, raccoon, and even
squirrels. In addition, tall buildings and
vanity signs that remain lit throughout the
night are as hazardous as lighted towers.
Birds may be attracted to these struc-tures,
confused by the lights, and circle
repeatedly, dying of exhaustion or by
colliding with the building.
Solutions ~ There are many ways to
reduce bird strikes at windows.
• Hang ribbons, wind chimes, or hawk
silhouettes the full length of the glass
outside windows, using a suction cup.
Movement is more effective in deterring
birds than static images on the glass.
• Move house plants away from windows.
• Place bird feeders, birdbaths, and plants
less than half a meter from windows, so
that birds are less likely to build up
enough momentum to harm themselves.
• Close curtains and blinds whenever
possible.
• Use window films that lessen the glare
and transparency of glass.
• Extinguish building lights or draw blinds
from dusk until dawn.
Transportation
Travel by air and car is a convenience that
is relatively safe for humans, but results in
death for as many as 2 million birds each
year. The over 8 million miles of roads in
the U.S. and hundreds of airports are often
bordered by fences and vegetation, which
are used by birds for perching, foraging,
and nesting. The heat emitted by road and
runway surfaces, puddles that form beside
roads, and the salt used for de-icing are
just a few of the other factors that attract
birds. Collisions with cars are also influ-enced
by location of the road, proximity of
vegetation, and vehicle speed.
Solutions ~ Erect road signs or speed
bumps to lower vehicle speeds where bird
activity is frequent and remove plants from
roadsides and medians that attract birds.
Landscaping with taller trees and bushes
will cause birds to fly higher. Better
planning of new roads and highways
will benefit birds by avoiding valuable
habitats.
For More Information on Bird Collision Issues:
American Bird Conservancy Wind Energy Policy - www.abcbirds.org
Avian Power Line Interaction Committee - www.aplic.org
Birds & Buildings - www.birdsandbuildings.org/index1024.html
Fatal Light Awareness Program - www.flap.org
National Wind Coordinating Committee - www.nationalwind.org
U.S. Fish & Wildlife Service - http://migratorybirds.fws.gov/issues
