Warmer, Dimmer Lights at Grand Teton: Visitors Liked Them Better, and Wildlife Benefits

People are often assumed to want bright, daylight-like light at night — it feels safer. A study at Grand Teton National Park suggests that in a national park, at least, visitors are happy with something gentler, and that the change helps wildlife, night skies and the park's budget.

With lower, red-hued lighting, visitors can now see the Milky Way at Grand Teton. Photo by the National Park Service

The study

The NPS Natural Sounds and Night Skies Division, Grand Teton, Boise State University and Pennsylvania State University replaced the 32 streetlights of Colter Bay Village with lights that could be dimmed and switched between colors. They surveyed visitors on cool white and blended red-white (amber) light: how it affected their nighttime activities, how they thought it affected wildlife, and whether they supported changes such as wildlife-friendly light colors. The study is published online.

What visitors thought

• Visitors preferred the red-white blended light, found it more comfortable to see by, and enjoyed nighttime activities more under it.
• They supported lighting that benefits the park and its wildlife over lighting that imitates daylight.
• It was the first outdoor lighting study to find this — perhaps because people in a national park expect different lighting than at home in a city or suburb.

One visitor wanted to know where to buy the amber bulbs for their own home, said Jennifer Newton, a Grand Teton social scientist and co-author.

Why warm and even is better

Bright light can actually make it harder to see at night: moving between brightly lit and dark areas strains both human and animal eyes. Uniform, warmer light, such as amber, preserves night vision — which is safer — and leaves more chance to see stars and wildlife.

Left and center: new warm-white and red-white blended lights; right: the old cool-white light. Photo by the National Park Service

Effects on wildlife

"Any organism that is active at night and has evolved vision is going to be affected," said Kurt Fristrup, a former branch chief of the night skies division and a co-author.

• Insects, bats and migrating birds mistake bright lights for stars and circle them, wasting energy and risking injury and death.
• Light on the ground disrupts predators and prey at night.
• The distribution and activity of twelve bat species changed with different lighting.
• Effects reach hundreds of meters into forests thought to be undisturbed; in Grand Teton, no area is untouched by artificial light and glow.

"Park visitors and wildlife experience many of the same benefits from dimmer blended red-white lighting," Fristrup said: better night vision and easier transitions between lit and unlit areas.

Lessons for parks

• Explain changes to visitors — "Make sure the park visitors are kept in the loop," Newton said, "and they'll usually be on board."
• New lighting pays for itself in lower energy and maintenance costs.
• Given strong support, other parks could try similar lighting.

Sources

Based on "Everyone can benefit from updated lighting in national parks, study finds," by Clara Deforest Colvig, working with the NPS Natural Resource Stewardship and Science Directorate through a Conservation Legacy placement, December 2024, National Park Service; rewritten in hubnx's own words. Quotations are from National Park Service scientists.