Land & Environment

Ask an Expert — Holiday Lighting May Not Be So Jolly for Wildlife

By Terry Messmer |

The holidays are here, and festive lights are burning bright. Although this tradition of illumination brings joy to many, it can also be considered a source of light pollution.

The International Dark-Sky Association coined the term “light pollution” to define excessive nighttime or non-natural lighting. The term applies to any adverse effect of artificial light, including sky glow, glare, light trespass, light clutter and energy waste. In addition, light pollution can affect astronomers and scientists, wildlife migrations and activity, and has been linked to human health concerns.

Migrating birds that use the moon and stars for navigation can be attracted by light beams from high-rise buildings, towers, lighthouses, oil platforms, etc., causing them to become disorientated and resulting in more accidents. In addition, nighttime predators have the advantage of seeing over a greater area, and their prey must seek darkness and spend more time hiding and less on everyday activities.

A recent study published in “Human-Wildlife Interactions” explains the effects of holiday lighting on the environment during regular periods of darkness. Wildlife students at Texas A&M University-Kingsville reported that holiday lights used to decorate the college campus were a seasonal source of light pollution that contributed to a higher predation rate for native eastern fox squirrels. Eastern fox squirrels exhibited normal daytime/nighttime behaviors throughout the year but extended their foraging behavior nearly 4 hours after sunset with the addition of holiday lights. The students documented that monthly squirrel mortality increased seven-fold with the addition of holiday lights, possibly due to the extension of their foraging time.

Additional studies suggest that the public is often unaware that bright lights can negatively alter wildlife behavior. Because of this, the students recommended educating the public about how light pollution affects wildlife and the environment. Consider these suggestions:

  • Check to see if there is a “Lights Out” program in your community. Some cities have adopted a program where interior and exterior lighting in tall buildings is dimmed or turned off during bird migration. Bare bulbs or upward-pointing lights are replaced with hooded fixtures that only shine downward. If lights can’t be turned off, a flat lens is used as well as a reduced number of lights and intensity.
  • Turn off outdoor lights that aren’t needed in the evenings and turn off holiday lights when you go to bed.
  • Reduce light intensity by using fewer outdoor lights or using colored lights rather than clear white bulbs. Research shows that colored lights are least attractive to wildlife and may lessen the negative effects on them.
  • Consider your relationship with the environment and how your actions affect it.

Thoughtfully weigh decisions dealing with cost, safety, health and environmental well-being when planning and using exterior illumination.

To access the full research report, visit


Terry Messmer
Wildlife Specialist


Extension 449stories Wildlife 141stories

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