Laura Erickson's For the Birds

Last week, I talked to my friend Bill Evans, who maintains a website, towerkill.com, that gives a clear picture of just how many communications towers there are in the U.S., and how these towers attract and kill nocturnal migrants.

I find it personally sad that communications towers are so lethal to birds, since For the Birds airs over them. The problem is that birds migrating at night navigate by the stars. Their system used to work perfectly, until people added electrical lights and tall obstructions to the migratory equation. When there is a low cloud cover or fog, birds fly lower than usual and are attracted to the warning lights required on tall towers to keep airplanes safe. Once they fly within the lighted space, they’re reluctant to head back out into darkness and get disoriented, bonking into the tower, the guy wires, and one another. On a single foggy September night in the 1960s, over 20,000 birds were killed at one TV tower in Eau Claire, Wisconsin, and 35,000 were killed on one foggy weekend. Most tower kills are far less dramatic than that one. This year on October 9, a TV tower in Topeka, Kansas, killed 450 migrants of 30 species, mostly warblers. This was an unusual case because there were absolutely no weather conditions that accounted for the numbers.

Technological advances are always going to come at a cost. The question is how much we’re willing to spend to minimize the damage or even reverse it. In the case of towers, it’s going to be decades before we can transmit the bulk of TV signals via satellite or cable, and radio signals will probably always go out primarily over the airwaves. If the tower are, in fact, necessary, and if commercial station operators are making big profits, then it seems that they should be responsible for conducting at least minimal research into finding light colors and flash patterns that will at least minimize the kill. The red lights currently used are apparently more dangerous to birds than white lights would be, but people usually find white lights more irritating and visually unaesthetic. When lights flash and stay off for a second or two before flashing back on, more birds have a chance to fly out of the lighted space and clear the tower area before the next light pattern. It seems to me that the telecommunications industry should take the lead in this research to minimize kills.

Another serious problem is the sheer numbers of towers, currently more than 40,000 in the United States and growing daily as new towers sprout up to hold antennas for the new high-definition television signals that will soon be transmitted. Digital TV signals are powerful and expensive, and to minimize the costs, these antennas are often being put on monster towers two thousand more more feet high rather than piggybacked on existing towers that are shorter. This may well cause high mortality even on nights when there isn’t a low cloud ceiling.

There are so many things that kill birds that no single cause of mortality can be considered the primary one. Collisions, cats, pesticides, and habitat destruction are probably the four biggest killers. We can’t fully solve any of the four problems, but we can and should minimize the carnage as much as possible. It’s the least we can do.