Town streetlights
Grants for fully shielded, warm or amber streetlights and lights on town buildings, put in by the power company or a licensed electrician.
Darker nights for Bryce Valley’s wildlife
We plan to help Tropic replace exposed outdoor lights with shielded, warm lighting, starting near wildlife habitat. Cannonville and Bryce Canyon City could follow.
Planned As of October 6, 2026: plan and research written. No town contacted; nothing funded or installed.
Why here
Utah’s wildlife agency maps Bryce Valley as mule deer winter range, so deer are near these towns in the longest nights of the year. A migration route of the Boulder deer herd, about 7,000 animals, reaches the valley near Tropic.
Bryce Canyon lists 14 kinds of bat. Seven are Myotis, a group known to avoid light. The park’s own sky measurements found its night sky influenced by the lights of neighboring towns, Tropic among them.
Shielding and warmer light also keep glare out of neighbors’ windows and keep more stars visible over town.
Derived Where Bryce Valley’s lights are. Orange squares are NASA satellite measurements of night light (Black Marble, May to October 2025, about 400 m across); town limits from Utah’s geographic office; park boundary from the National Park Service. Wildlife ranges are not drawn here: see the state’s habitat maps and USGS (2024), figure 19.What the research shows
Studies of light at night, the animals that live here, and how strong the evidence is for each.
| Animals and plants, and evidence | What studies found |
|---|---|
| Bats Strong | Light-shy bats such as the little brown myotis avoided white LED light even 75 m away, at less than 1 lux (Seewagen and others, 2023). Avoidance reached 50 m from streetlights, and the authors recommend keeping streetlights at least 50 m from wildlife corridors (Azam and others, 2018). Dimmed to a quarter of their output, LEDs made no significant difference to these bats (Rowse and others, 2018). |
| Night insects and moths Strong | Street lighting cut moth caterpillar numbers by 33 to 47%, and white LEDs did more harm than sodium lamps (Boyes and others, 2021). Moth populations fell under experimental lampposts after three years (van Grunsven and others, 2020). Amber and warmer light draws fewer insects (Deichmann and others, 2021; Bolliger and others, 2022). |
| Night-blooming plants Moderate | Lit meadows had 62% fewer visits from night pollinators and 13% less fruit (Knop and others, 2017). Bryce’s yuccas depend on yucca moths for pollination (Pellmyr, 2003); whether town lights affect them here is not known. |
| Mule deer and cougars Moderate | Deer used the most brightly lit places less and moved faster through lit stretches of their routes (Ditmer and others, 2023). At the edges of towns, cougars killed deer in the darkest spots (Ditmer and others, 2021). Black-tailed deer crossed under an unlit section of an underpass much less when the section beside it was lit (Bliss-Ketchum and others, 2016). These studies are from larger towns and cities. |
| Elk None found | We found no study of elk and outdoor lighting. |
| Migrating birds Low here | Very bright city lights draw and disorient birds migrating at night (Van Doren and others, 2017). Radar estimates millions cross Garfield County each fall (BirdCast), but the effect of a small town’s lights is likely small. |
We do not claim this work will increase deer, bats or any other wildlife. What it does is remove a stressor that studies have documented, from places wildlife is mapped to use.
What changes for certain
- Direction. No light goes up or sideways into fields, the river corridors or the sky.
- Color. Warm or amber light, with little of the blue that draws insects most.
- Amount. The lowest output that does the job.
- Hours. Dimming or switching off late at night, where a town wants it.
- Energy. A shielded LED uses roughly a third of the power of the sodium lamp it replaces.
Before: light goes everywhere
After: only where it is needed
Illustration A wall light before and after a shade. Drawings by Bryce Canyon Conservancy after NPS lighting guidance (2025); the rays are schematic, not measured.What we plan to fund
Planned Nothing is funded yet. Before any money moves, an independent board adopts a written grant policy and each town signs an agreement. The towns make their own rules.
Homes
Up to $200 a household (proposed) for shielded porch and yard lights, paid after a short night-time check by a trained volunteer.
Businesses
Half the cost of new fixtures, up to $1,000 (proposed), where the public benefit of less glow is the point.
Help and nights out
A count of the towns’ lights, a one-page fixture guide, and two community nights a year.
How we would know
Planned Nothing is installed. The bat recordings would run in the summer before the change and the summer after.
Light count
- Question
- What share of the towns’ lights is shielded, warm and no brighter than needed, and is it rising?
- Upkeep
- The same survey every spring; homes only with the owner’s yes.
- Output
- A table for each town: lights changed and the share that meets the standard.
This is the main measure. It is not code enforcement.
Bat recorders
- Question
- Do bats use the dark around a light more after it is changed, compared with lights left as they are and dark places nearby?
- Upkeep
- Small ultrasonic recorders at 12 places; batteries and cards changed every 8 to 10 nights.
- Output
- Bat passes per night for each group of bats, before and after.
Activity is not the number of bats. Only large changes would show.
Sky meter, later
- Question
- Is the sky overhead at the edge of town getting darker?
- Upkeep
- Data downloaded monthly; checked after storms.
- Output
- Sky brightness for each clear, moonless night, beside the park’s own record.
Not in the first year’s budget. Weather and the moon move the readings; a reading does not show which lights changed.
Satellite check
- Question
- Did each town’s total light, as seen from orbit, go down?
- Upkeep
- Once a year, from free NASA data.
- Output
- One number for each town and year.
From 2013 to 2025 the towns stayed level within about 20%, and the satellite cannot see blue light, so only big changes would register.
Sources
- Utah Division of Wildlife Resources, Wildlife Habitats Map (mule deer and elk seasonal habitat; migration corridors).
- Kauffman, M., and others, 2024, Ungulate migrations of the Western United States, volume 4, USGS SIR 2024–5006 (Boulder mule deer herd, figure 19).
- National Park Service, Bats of Bryce Canyon; NPSpecies list for Bryce Canyon (bats, plants).
- Baril, L., Struthers, K., and Valentine-Darby, P.L., 2018, Bryce Canyon National Park: Natural resource condition assessment, NPS/NCPN/NRR—2018/1690 (night sky, pages 40–50).
- Seewagen, C.L., and others, 2023, Far-reaching displacement effects of artificial light at night in a North American bat community, Global Ecology and Conservation 48.
- Azam, C., and others, 2018, Evidence for distance and illuminance thresholds in the effects of artificial lighting on bat activity, Landscape and Urban Planning 175.
- Rowse, E.G., Harris, S., and Jones, G., 2018, Effects of dimming light-emitting diode street lights on light-opportunistic and light-averse bats, Royal Society Open Science 5.
- Boyes, D.H., and others, 2021, Street lighting has detrimental impacts on local insect populations, Science Advances 7.
- van Grunsven, R.H.A., and others, 2020, Experimental light at night has a negative long-term impact on macro-moth populations, Current Biology 30.
- Deichmann, J.L., and others, 2021, Reducing the blue spectrum of artificial light at night minimises insect attraction, Insect Conservation and Diversity 14; Bolliger, J., and others, 2022, Contrasting effects of street light shapes and LED color temperatures on nocturnal insects and bats, Basic and Applied Ecology 64.
- Knop, E., and others, 2017, Artificial light at night as a new threat to pollination, Nature 548; Pellmyr, O., 2003, Yuccas, yucca moths, and coevolution: a review, Annals of the Missouri Botanical Garden 90.
- Ditmer, M.A., and others, 2021, Artificial nightlight alters the predator–prey dynamics of an apex carnivore, Ecography 44; Ditmer, M.A., and others, 2023, Navigating the wildland-urban interface, Basic and Applied Ecology 73.
- Bliss-Ketchum, L., and others, 2016, The effect of artificial light on wildlife use of a passage structure, Biological Conservation 199.
- Van Doren, B.M., and others, 2017, High-intensity urban light installation dramatically alters nocturnal bird migration, PNAS 114; BirdCast, Garfield County.
- Kyba, C.C.M., and others, 2017, Artificially lit surface of Earth at night increasing in radiance and extent, Science Advances 3 (the satellite’s blind spot for blue light); NASA Black Marble night-light data through NASA GIBS.