As far back as 1994, environmental scientists began noticing the effect of human lighting on animal populations. Colin Henshaw - an astronomer with a tangential interest in wildlife - wrote a letter to the Journal of the British Astronomical Association predicting that a reduction in insect populations would affect predators higher up the food chain like birds (you can view Henshaw's letter to the Junior British Astronomical Association, or JBAA, here, or you can track his notes on Facebook).

Henshaw's paper, The Environmental Effects of Light Pollution also makes interesting if disturbing reading for bird lovers, revealing as it does an insect population decline notable even 14 years ago. But the average person doesn't need a scholarly paper to know that everything from lighted skyscrapers at night to backyard bug lights are destroying insects at an alarming rate. And once you get rid of bugs, can birds - most of which feed on insects to a greater or lesser degree - be far behind?

Insects are also the primary food source for many other species, like bats, lizards, frogs and even salamanders. Additionally, insects pollinate plants. Fewer insects mean less successful pollination and fewer plants. But let's stick to birds, including the migratory, nocturnal songbirds highlighted in the report below.

In 2008, the Charlestown (W. Va.) Daily Mail reported the deaths of "hundreds" of yellow warblers. This small, golden bird travels from Columbia, Panama and Puerto Rico in the spring and fall, typically at night. One night they arrived in Hambleton in the midst of fog, and - disoriented by the lights of a school building sitting on a hill - proceeded to crash into the walls of the building and die.

Ornithologists call this an example of "tower kill", where night-migrating birds (which often navigate by starlight) are disoriented by artificial light sources. In the human world, this would be like moving a traffic signal inside a store window at night. The same thing happens to birds around cellphone towers, skyscrapers and other tall, lighted structures when fog or other weather conditions confuse their senses.

According to Michael Mesure, executive director of the Fatal Light Awareness Program (FLAP), a Toronto-based environmental organization, "Over 450 bird species that migrate at night across North America are susceptible to collisions with night-lit towers, including threatened or endangered species like the cerulean warbler and Henslow's sparrow."

To back up his statement, Mesure cites two consecutive nights in 1954, when 50,000 birds died at Warner Robins Air Force Base, Georgia, following runway lights right into the ground. In 1981, over 10,000 birds slammed into floodlit smokestacks at the Hydrox Generating Plant near Kingston, Ontario.

It isn't just migratory, or land birds, that are in danger from our overly bright nighttime world. The Leach's petrel, which feeds just offshore on bioluminescent plankton, is drawn to the lights of oil drilling platforms and ship's superstructures, and frequently ends up injured or dead as a result of these pseudo-kamikaze flights.

Artificial lighting in unnatural places, at unnatural times - commonly referred to as light pollution - not only kills insects and the birds which feed on them, but can cause birds to migrate in the wrong direction or choose bad nest sites - or mates - and can even affect hunting ability.

By "unnatural", I mean alien to the natural world. People have been lighting their structures since the dawn of civilization. Only in the last century, however - or since the invention of the electric light bulb and its increasing use to transform the nighttime world - has light pollution become a source of real concern to ornithologists and environmentalists.

It isn't just the light either, but its reflection - known as polarized light - that confuses birds, which see in the smooth, dark surfaces of asphalt roads, for example, a pond, and dive to what they imagine is a food source or a bath. The results are inevitable and often tragic.

Bruce Robertson, an ecologist at Michigan State University, explains that the primary source of horizontally polarized light in nature is water, and goes on to note that, as early as the 1980s, biologists understood that such polarized light is an amazingly reliable clue (for birds, insects and other inhabitants of the natural world) for finding bodies of water and the food sources they provide.

Polarized light aside, the real dangers to birds remain tall, lighted structures on foggy nights. A 2004 forum post to a thread on Minneapolis skyscraper dangers to birds notes: "Just one night a few weeks back almost five hundred birds were found dead under an Anoka (broadcast) antenna."

This situation is being duplicated thousands of times across the United States, in Europe, and in other developed countries, leading to a bleak fulfillment of Rachel Carson's prophecy as revealed in her book, The Silent Spring.

Carson was targeting chemical pollution from pesticides. Light pollution is a newer, previously unseen, threat (no pun intended). Add them together, and we may be witnessing species extinction on a scale to rival the Permian-Triassic extinction event, which killed 70 percent of all land species.

For those who still doubt their backyard bug light or city lights at night are a serious problem, I invite you to read Dr. Alex Pollard's paper, Street lighting - a birds eye view. Pollard's paper is full of informative graphs and charts for bird lovers, especially those who are beginning to note the absence of these feathered treasures from fields, trees, backyards, and bird feeders.

Related Reading:
Acid, Algae, and the Case of the Disappearing Pelican
Climate Change Causes Caterpillar Kerfluffle