Biological clock and circadian rhythm International Dark-Sky Association Animals and plants live by To preserve and protect the nighttime environment and our heritage of a rhythm which is attuned dark skies through quality outdoor lighting. to our planet’s 24-hour cycle. !is is an inherited trait, which is passed on Light Pollution and Wildlife Peter Wienerroither through the genes of a species. Humans may Dave Wymer notice a change in their circadian rhythm when they travel by airplane between several time zones, charac- The International Dark-Sky Association (IDA), is an terized by sleepiness, lethargy, or a general sense that educational organization that seeks to preserve the natu- something is “off.” ral night skies worldwide. Light pollution is an increasing problem threatening astronomical facilities, ecologically Wildlife and fish experience this same disorientation sensitive habitats, all wildlife, our energy use as well as of time when there is too much artificial light at night. our human heritage. Light pollution is excessive and inap- Behavior governing mating, migration, sleep, and find- propriate artificial light. !e four components of light ing food are determined by the length of nighttime. pollution are often combined and overlapping: Light pollution negatively disrupts these age-old pat- terns. See inside for details about the ill-effects of light • Urban sky glow—the brightening of the night pollution on our environment and wildlife. sky over inhabited areas. • Light trespass—light falling where it is not intended, wanted, or needed. • Glare—excessive brightness which causes visual discomfort. High levels of glare can decrease visibility. • Clutter—bright, confusing, and excessive group- ings of light sources, commonly found in over-lit urban areas. !e proliferation of clutter contrib- utes to urban sky glow, trespass, and glare.

Keeping lights on in unoccupied buildings, outdoor lights pointing up to the sky or unshielded lights create sky glow.

Jeremy Stanley Visit the IDA Web site at www.darksky.org to learn more about the causes of light pollution and what you can do to keep the skies dark. 3225 N. First Ave. Tucson, AZ, 85719 International Dark-Sky Association images may only be used USA for noncommercial, educational purposes and must compliment Phone +1 520-293-3198 IDA!s mission to preserve and protect our night skies through Fax +1 520-293-3192 quality outdoor lighting www.darksky.org • Images attributed to IDA must be credited as such. [email protected] • Images credited to anyone other than IDA may not be This brochure was made possible by used without the consent of the photographer. funding from the Gildea Foundation © 2008 International Dark-Sky Association US Fish and Wildlife Mammals Amphibians Insects

!e bright lights from cities and !e haze from sky glow extends Moths and other insects are towns cause nocturnal mammals far beyond the borders of an attracted to artificial lights and may across the globe to experience urban city, impacting the envi- stay near that light all night. !is a loss of their night ecosystem. ronment for miles, including activity around the light: Examples of these affected mam- wetlands, the natural habitat of US Fish and Wildlife mals are bats, raccoons, coyotes, amphibians. It causes amphib- • Expends too much energy Alexi Pace Michael Menefee deer and moose. These species ians, and other creatures of the marshes, to become and interferes with mating can experience: confused and disoriented, causing: and migration, causing population reduction • Makes them easy prey for bats and other • A decline in reproduction, leading to a shrink- • A decrease in reproduction, resulting in lower nocturnal predators, further reducing their ing population populations numbers • Difficulty foraging for food due to too • Reduced foraging for food and lower body • Impacts all species who rely on insects for food much light weight or pollination • Exposure to predators that would otherwise • Confusion of natural instincts that protect against be unable to see them predators and the elements There are solutions • Increased mortality caused by impairment of their night vision Reptiles IDA believes that there are solutions to these issues:

Birds Donna Dewhurst USFWS Reptiles are greatly affected by light • Shield your outdoor lighting pollution. For example, female sea • Only use the light when you Many species of birds turtles like to nest on remote and need it migrate or hunt at night very dark beaches. Coastal lights • Use timers and dimmers This dependence on dark- interfere with their ability to find • Shut off the lights when you can ness makes them extremely a safe nesting area for their eggs. • Use only enough light to get the vulnerable to bright lights in Sea turtle hatchlings crawl instinc- job done Michael Menefee areas that are naturally dark. tively toward the relative safety of • Use long wavelength light with Birds can be drawn to light sources and become fixated the ocean because of its reflection of the moon and stars. a red or yellow tint to minimize on the beam. !is confusion causes a variety of negative For centuries, this reflection was the brightest point of light GlareBuster impact effects, such as: on a beach. Artificial lights can confuse the hatchlings and cause them to crawl away from the ocean and onto roads or A shielded light uses less wattage and saves you money. • 100 million birds a year throughout North into communities. If they do not find their way back to the Work with your neighbors and local government to America die in collisions with lighted buildings ocean, they could become fatally exhausted or dehydrated. keep the skies natural. !is is a win-win situation and towers Nocturnal reptiles can also become disoriented by the arti- for everyone. You save money while simultaneously • Not wanting to fly back into the dark, they ficial light invading their homes and experience a change in reducing the impact of artificial light at night. continue to fly in the light’s beam until they are natural behaviors. !ese behaviors might include: exhausted, fall or become prey • !e artificial lights can also cause migrating • Appetite problems resulting in decreased weight birds to wander off course and never reach their • Decrease in mating, resulting in diminished natural destination populations • Marine birds have been known to collide • Increased vulnerability to natural predators and with lighthouses, wind turbines and drilling unusual ones like cars and humans Todd Carlson platforms at sea Before and during the East Coast blackout, 2003