A Blog Around The Clock

Light Pollution

There is a nice article in this month’s National Geographic about Light Pollution. Unlike most popular articles on the topic which focus on the visibility of stars – an aesthetic problem – this article focuses on the effect of continuous light on animals and humans:

We’ve lit up the night as if it were an unoccupied country, when nothing could be further from the truth. Among mammals alone, the number of nocturnal species is astonishing. Light is a powerful biological force, and on many species it acts as a magnet, a process being studied by researchers such as Travis Longcore and Catherine Rich, co-founders of the Los Angeles-based Urban Wildlands Group. The effect is so powerful that scientists speak of songbirds and seabirds being “captured” by searchlights on land or by the light from gas flares on marine oil platforms, circling and circling in the thousands until they drop. Migrating at night, birds are apt to collide with brightly lit tall buildings; immature birds on their first journey suffer disproportionately.

Insects, of course, cluster around streetlights, and feeding at those insect clusters is now ingrained in the lives of many bat species. In some Swiss valleys the European lesser horseshoe bat began to vanish after streetlights were installed, perhaps because those valleys were suddenly filled with light-feeding pipistrelle bats. Other nocturnal mammals–including desert rodents, fruit bats, opossums, and badgers–forage more cautiously under the permanent full moon of light pollution because they’ve become easier targets for predators.

Some birds–blackbirds and nightingales, among others–sing at unnatural hours in the presence of artificial light. Scientists have determined that long artificial days–and artificially short nights–induce early breeding in a wide range of birds. And because a longer day allows for longer feeding, it can also affect migration schedules. One population of Bewick’s swans wintering in England put on fat more rapidly than usual, priming them to begin their Siberian migration early. The problem, of course, is that migration, like most other aspects of bird behavior, is a precisely timed biological behavior. Leaving early may mean arriving too soon for nesting conditions to be right.

Nesting sea turtles, which show a natural predisposition for dark beaches, find fewer and fewer of them to nest on. Their hatchlings, which gravitate toward the brighter, more reflective sea horizon, find themselves confused by artificial lighting behind the beach. In Florida alone, hatchling losses number in the hundreds of thousands every year. Frogs and toads living near brightly lit highways suffer nocturnal light levels that are as much as a million times brighter than normal, throwing nearly every aspect of their behavior out of joint, including their nighttime breeding choruses.

Read the whole thing

Comments

  1. #1 Gray Gaffer
    November 13, 2008

    Humans are also affected. In particular, many have no idea of the splendor of a dark sky. Fixing this also save a lot of energy and money. Much of the typical lighting energy goes up into the sky and illuminates nothing, but obscures the stars. A good billion goes up, not even in smoke, this way.

    Our local Astronomical Society has a few good links at:

    http://www.bpastro.org/index.php?page=light-pollution-links

  2. #2 Coturnix
    November 13, 2008

    Yes, that is all also in the article. But I still like the rarely seen biological focus. It’s always astronomy (which is fine, but sometimes they don’t even mention the effects on human health or animal behavior).

  3. #3 Larry Jordan
    November 14, 2008

    Thank you for bringing this problem of light pollution to the attention of the general public. This is a huge problem for our migrating bird population. Birds are interrupted on their night migrations by the light pollution from city lights and drawn off course. Thousands of birds are caught in the maze of tall buildings and perish because we leave lights on in high rise buildings in our cities.
    One group has begun to fight against this problem to the betterment of all of us. The Fatal Light Awareness Program (FLAP) is beginning to make a difference. Turning out unnecessary lighting in buildings at night not only helps the birds but saves huge sums of money on electric bills and is the environmentally friendly way to run any business.
    I wrote a post on window kills and light pollution you may enjoy here: http://www.thebirdersreport.com/birds-in-the-news/windows-kill-100-million-to-a-billion-birds-a-year
    Thanks again for sharing this great information!

  4. #4 Jina Saccacio
    November 14, 2008

    My website includes information on all of the harmful aspects of light pollution and some remedies.Keep spreading the word and learning. This can be fixed.

  5. #5 Luna_the_cat
    November 15, 2008

    Another biological aspect of light pollution which I have run across — at least a potential one — is a posited link with breast cancer. It sounds crazy, but one undeniable observation is that rates of breast cancer increase in every population with industrialisation, and a lot of teams have been looking into why. One possible why was triggered by the observation that women who work night shifts appear to have a statistically significant higher incidence of breast cancer than women who don’t, in otherwise matched populations — and this triggered the hypothesis that exposure to light for extended hours messed with some of the hormone balances in a way which left predisposed individuals more vulnerable to the development of breast cancer.

    I don’t think nearly enough research has been done yet to see if this idea pans out to anything real — but it is an interesting idea.

    And speaking as someone who worked night shifts for about three years, it does really mess with you.

The site is currently under maintenance and will be back shortly. New comments have been disabled during this time, please check back soon.