September, 1998
Although you might think of your wireless telephone and digital TV as benign technology, they pose a real and mostly unknown risk to migratory birds. The millions of birds migrate every year have been the subject of great concern for ecologists, who have watched their numbers dwindle over the decades, with really rapid declines appearing since the 1960s. These birds are vulnerable to habitat loss in both northern breeding range and southern wintering range, but now another, more subtle, threat seems to be exacerbating their decline: transmission towers for cell phones, digital TV, and other communication devices. Actual numbers of deaths are unknown, but some researchers estimate mortality from collisions with towers between 2 million and 5 million birds in the United States every year.
Migrating warblers make up a large proportion of birds killed in collisions with communications towers. |
The principal problem with these towers is that they are very tall and that they are lit to prevent airplane collisions. Currently there are nearly 80,000 communications towers standing 200 feet tall and higher. Many birds migrate at night and navigate by the stars, and when they encounter the high beacon lights of a transmission tower, they appear to become confused, especially on cloudy nights. Flying near to the lights and sometimes circling them in confusion, birds collide with the unlit guy wires that support the towers.
To make matters worse, increasing demand for communications is expected to require the construction of 100,000 new towers in the next ten years. Worst among these will be the extremely tall towers required for digital TV transmission, each at least 1000 feet--1/5 of a mile--tall. This height puts these towers well into the elevation at which many birds migrate. The Federal Communications Commission is pushing to exempt these towers from local zoning control, so that television networks could legally override any local concerns about the placement of these towers.
Meanwhile the communications industry points to an insatiable demand for communication technology, which requires that they install ever more and taller towers. To restrict construction would be to restrict interstate trade, one of the most important central tenets of American commerce. The industry's imperative is to satisfy customer demand, not to conserve migratory warblers.
Some scientists and citizens concerned about birds have begun collecting data and trying to publicize the problem. Especially active have been ornithologists at Cornell University, which maintains the country's leading ornithological research center. For further information, including maps of the distribution and height of communications towers in your state, see the web pages listed below.
For further information, see these related web sites:
Lots of information on towers and
birds, with maps of towers in your state
(Site maintained by Cornell Ornithology Lab)
To read more, see
Environmental Science, A Global Concern,
Cunningham and Saigo, 5th ed.
Benefits of biodiversity: page 374
Threats to biodiversity: pages 275-283
Environmental Science, Enger and Smith,
6th ed.
Migration routes in North America: page 209
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