International Dark Sky Week begins April 13, 2026, drawing attention to light pollution and its effects on wildlife across Maryland. The annual observance, running through April 20, encourages residents to reduce unnecessary artificial light at night to protect migrating birds, bats, insects and other species while improving views of the night sky.
Light pollution, defined as excessive human-produced light during nighttime hours, creates significant challenges in Maryland due to the state’s population density. Ambient light levels rise highest near urban centers, yet even distant sources can disrupt surrounding natural environments. For many animal species, artificial light at night causes disorientation, altered behavior or increased mortality risk.
Maryland lies along the Atlantic Flyway, a primary migration corridor for birds traveling between breeding and wintering grounds. Most songbirds and shorebirds migrate at night. Kevin Stohlgren, Maryland’s state zoologist with the Department of Natural Resources Wildlife and Heritage Service, explained that light pollution disorients these travelers. “Light pollution is disorienting—it can cause birds to make collisions from reflections off of glass, or make birds lose energy on that important route,” Stohlgren said.
Up to one billion birds die annually in the United States from building collisions, many linked to light pollution that draws night-flying migrants into populated areas. Groups such as DarkSky International and the National Audubon Society promote “lights out” initiatives during peak spring and fall migration periods. In Baltimore, Lights Out Baltimore coordinates efforts to turn off non-essential lighting and organizes volunteer teams to rescue injured birds.
Bats also face disruption from artificial light. Species including little brown bats and big brown bats, both present in Maryland, experience altered foraging patterns and reduced available habitat. Light can delay their emergence at dusk or cause them to avoid illuminated areas altogether, increasing vulnerability to predators.
Insects suffer as well. Max Ferlauto, Maryland’s state entomologist, noted that light pollution interferes with feeding and mating behaviors, particularly for moths and fireflies. Insects drawn to lights become easier targets for predators such as spiders, and illuminated gardens lose suitability as habitat for nocturnal pollinators like moths.
Other wildlife respond variably to light. Some prey species avoid brightly lit zones, while certain fish may gather near lights to feed on attracted invertebrates, exposing themselves to greater predation risk. Sea turtles, though nesting primarily south of Maryland, can experience disorientation from coastal lighting that affects both nesting adults and emerging hatchlings.
Human health also benefits from darker nights. Reduced light pollution helps maintain natural circadian rhythms and improves sleep quality while restoring opportunities to observe stars.
Simple actions can mitigate the problem. Stohlgren emphasized that individual efforts make a difference. “It’s one of those easy things everyone can do to make a difference,” he said. “A big portion of strikes and negative effects of lights come from just residential houses. Turning your lights out or making your home more wildlife friendly has low or no cost and requires little effort, but it’s a great way to participate in conservation.”
Recommended steps include turning off unnecessary outdoor and indoor lights that spill outside, using shielded fixtures that direct light downward, installing motion sensors or timers, and choosing warmer-color bulbs with lower intensity. DarkSky International provides additional guidance on responsible lighting practices.
The Maryland Department of Natural Resources, working with DarkSky Maryland, scheduled several public events during International Dark Sky Week to promote awareness and enjoyment of natural darkness.
Events include:
- Stargazing at Tuckahoe State Park on Friday, April 17, at 8 p.m. at the Campground Ballfield. Attendees should bring warm clothes and a chair if desired. Contact mark.herring@maryland.gov for details.
- New Moon Night Hike at Sang Run State Park on Friday, April 17. Participants meet at 7:30 p.m. at the Friends Store for an 8 p.m. start on a one-mile guided hike. Red light flashlights are required. Contact ChristineN.Smith@maryland.gov with questions.
- Following the North Star: Exploring the Night Sky and Underground Railroad History with DarkSky Maryland on Saturday, April 18, at 7:30 p.m. at the Harriet Tubman Underground Railroad State Park Visitor Center in Church Creek. This event reached registration capacity.
- Stargazing Night at Janes Island State Park on Saturday, April 18, at 8 p.m. in the back of the marina parking lot in Crisfield. The free event includes telescopes. Contact the park for information.
- Crisis on Cosmology: The Hubble Tension, a lecture by the Westminster Astronomical Society on Saturday, April 18, at 8:30 p.m. at the Soldiers Delight Visitors Center. The program occurs rain or shine, and signup is encouraged.
Southern Maryland residents can participate by reducing outdoor lighting at homes and businesses, especially during migration seasons in April-May and September-October. Local parks and dark-sky advocates encourage families to experience natural night skies through these and similar events on the Eastern Shore and across the state. Reducing light pollution supports healthier ecosystems, protects migratory pathways and allows clearer views of the stars above Maryland’s waterways and forests.
