For the Birds Radio Program: Dark Sky

Original Air Date: July 10, 2007 Rerun Dates: June 13, 2008

Birders and astronomers should join forces in fighting against light pollution.

Duration: 4′02″


Night sky

This past week, people on the national Bird Chat listserv were discussing the decline of Common Nighthawks and possible reasons. I talked about disappearing mayflies, and someone else added a post about declining moths and other insects, and how outdoor lighting and some other factors have been major contributing factors in the insects’ declines. Bill Murphy wrote,,

Doug Ferguson, a lepidopterist at the U.S. National Museum of Natural History in DC, noted that the arrival of the mercury vapor lamp in remote areas in the Carolinas coincided with a drop of almost 90% in moth numbers within a few years. He postulated that they exhausted themselves after becoming locked into flying in circles around the lights. Their natural inclination apparently was to orient by the sun; thus their predilection to circle until they died.

Bill Murphy continues: I can vouch for the loss during the last 40 years of the former gigantic mayfly hatches, too. When I was a boy, the mayflies in eastern Lake Erie would produce prodigious numbers of adults each spring, so many that the city of Buffalo sometimes used graders to clear them from the streets. They’d pile up like snowdrifts on the shore, smelling like fish. Numbers dropped precipitously during the years of heavy phosphate use (1950’s and early 1960’s) and even further with widespread use of DDT on agricultural fields to the west, primarily in Ohio.

Bill concludes: From my readings I learned that the nighthawk population along the Ohio River had been much higher historically. I wonder if they might have nested on the many gravel bars in the river, all of which were submerged when the river was dammed. Several species of tiger beetles disappeared from the area concomitant with the damming. Do you think birders should consider giving thought to supporting black sky organizations as a possible means of reversing the loss of nocturnal insects?

It seems to me that the black sky organizations, started by astronomers desperate to keep at least some clear views of the night sky, have a lot of common goals with people who value birds. Light pollution squanders energy, which harms birds in countless ways, including all the ways populations are suffering from climate change, all the habitat loss from oil spills and coal mining, and mercury and other pollutants raining down from power plants. And the lights themselves not only attract insects—lights on high structures, such as communications towers and skyscrapers, draw in migrating birds and kill millions every year.

Night lighting does afford us humans some safety. But in most places there’s no reason why lights need to be as bright as they are, and they certainly don’t need to be shining upwards. And lighting for decoration, like the huge number of bright lights on the Blatnik Bridge in Duluth which make it look from a distance like a bizarre electric Volkswagon beetle, squander not just energy and environmental values but a lot of tax dollars. I’m going to start looking into organizations working to lower lighting. It seems like the right thing to do.