Approximately 6.8 million birds every year in the U.S. and Canada die because of the 84,000 communication towers in those countries. Birds are mesmerized by the lights on the towers and fly into cables supporting the structures, fly into each other, or are simply exhausted due to circling them for too long.
About 250,000 birds died in the Exxon Valdez oil disaster, but 27 times more communication tower bird deaths take place every year, said the researchers.
One factor which forces birds to fly at lower altitudes, and into the range of communication towers, is the lower cloud cover of inclement weather. The birds are then attracted to the red safety lights of the towers. Researchers say once the birds hone in on these lights, they are unable to stop circling the structures, leading to exhaustion or running into other birds or wires.
Scientists say solid red lights are the main cause of bird mesmerization and disorientation. If flashing lights are used instead of solid ones, the bird fatality rate can be cut nearly in half. Replacing solid lights
with flashing ones also does not reduce safety for aircraft, they said. Constructing free-standing towers without using guy wires can reduce bird deaths, as well.
Some of the millions of birds killed every year by communications towers are of conservation status, meaning they are threatened or endangered species. Most of the species killed by towers are migratory breeding in Canada and the U.S. but wintering south of the U.S. border. Known as neotropical migrants they have been documented to be in decline for some time, due to habitat loss and degradation. There are well over 300 species if neotropical migrants – some of them are warblers, vireos, flycatchers, and thrushes.
Another concern is the additional construction of new towers due to the popularity of the digital age. The researchers said theirs is the first estimate of bird deaths in the two countries due to communications towers. Over a dozen scientists collaborated on the survey.
You can read the whole study here if you like.
Image Credit: public domain by its author, Berichard