-
- The flutelike whistle of the wood thrush, the banjolike
melody of the bobolink and the cheerful singing of many other migratory
songbirds are being snuffed out by the electronic chirp of technology.
-
- Millions of the migratory birds, which yearly travel
through Chicago from as far north as Canada to as far south as Peru, are
being killed off by rapidly rising cellular telephone towers and new digital
television antennas blocking their paths, wildlife experts say.
-
- High-definition television towers can climb to heights
of 1,000 feet and are the latest threat to songbirds, which typically fly
at 5,000 feet but descend to much lower levels during overcast evenings,
said Albert Manville, a wildlife biologist with the office of migratory
bird management for the U.S. Fish and Wildlife Service.
-
- ``We're looking at an impact of between 4 [million] to
5 million birds killed each year just from the cellular telephone towers;
we know that towers are going up at an unprecedented rate,'' Manville said.
``HDTV towers are a train wreck we want to avoid. ... The concern is it's
yet another impact [on birds].''
-
- Manville and other experts are so worried about the newly
installed digital television or HDTV towers that they led a symposium recently
at New York's Cornell University to draw attention to the issue.
-
- According to the Federal Communications Commission, 48,642
cellular telephone towers at least 200 feet in height were in operation
last year. Digital towers recently went up as television stations prepared
for the advent of HDTV broadcasts.
-
- The antennas went up this month, at the end of the birds'
second migration.
-
- The birds typically migrate twice a year, traveling north
during the spring months from March to early June and south for the winter
months from August to December, said David Willard, collection manager
in the bird division of the Field Museum.
-
- The birds use stars as navigational tools, but during
overcast evenings they fly under the cloud cover. They are then drawn toward
lights on towers and buildings, Willard said.
-
- Several hundred different species of songbirds fly through
Chicago. While many of those birds, including warblers, sparrows and orioles,
are abundant, others such as the bobolink are so scarce that they're at
risk of being placed on the nation's endangered species list.
-
- The Kirtland's warbler, which calls the grasslands of
Michigan home, is so scarce that only about 2,000 pairs remain alive, Willard
said.
-
- Along their routes, birds typically encounter hazards
such as large picture windows, high-rise buildings and towers with guy
wires that help secure the antennas.
-
- ``Because of the other kinds of hazards for birds, people
are wondering how the [new towers] could not cause similar kinds of problems;
those kinds of structures have already been shown to be hazardous to birds,''
Willard said.
-
- Along with the towers, experts also are pointing to the
proposed ``stick building'' in the Loop as another problem for the birds.
The building is to be the world's tallest skyscraper.
-
- Tiny bird carcasses line drawers in the Field Museum
as examples of those that have struck buildings and other hazards in the
area.
-
- For reasons scientists haven't been able to explain fully,
the birds are drawn to red lights and radio signals, which might disrupt
the birds' navigation systems. The lights can be found at the top of the
towers and many buildings. The birds routinely circle around the lights
to regain their orientation but then hit guy wires holding up the structures,
said Vernon Kleen, an avian ecologist for the Department of Natural Resources.
-
- ``There are some [wires] that have killed as many as
1,000 birds a night, maybe more,'' Kleen said.
-
- Songbirds, which tend to be smaller than other varieties
of birds, fly at night, while most other birds fly during daylight. The
birds choose night to avoid larger predators and also use stars and ground
lights as navigation tools, Kleen said.
-
- ``Smaller birds fly at night to hide under the cover
of darkness,'' he said.
|
