Lights Out for Migrating Birds: Why Night Lighting Matters

One of the easiest bird-friendly actions does not require planting, feeding or buying wildlife equipment.

It can be as simple as turning off a light.

The reason is that billions of birds migrate at night. Artificial light can pull night-flying migrants toward illuminated buildings and landscapes, disrupt normal navigation, make birds circle and waste energy, and increase exposure to collision hazards.

“Lights Out” programs turn that science into a practical rule: use only the light you actually need, only where you need it, and especially reduce unnecessary lighting when migration is heavy.

Why So Many Birds Migrate at Night

Many songbirds and other migrants make long-distance flights after sunset.

Night migration can offer several advantages:

• cooler temperatures;
• often calmer atmospheric conditions;
• daylight hours remain available for feeding;
• navigation can use celestial and other environmental cues.

The U.S. Fish & Wildlife Service emphasizes that the natural cycle of darkness is important for the billions of birds that rely on nighttime migration.

How Artificial Light Changes the Night

Artificial light at night creates bright points, illuminated buildings and skyglow that did not exist in the environments under which migration evolved.

Night migrants can be attracted toward those light sources or become disoriented once they enter a brightly illuminated area.

U.S. Fish & Wildlife Service guidance notes that birds can be drawn toward lighting from kilometers away and may circle an illuminated area instead of continuing efficiently along their migration route.

Why Circling a Light Is Dangerous

Migration is an energy-intensive journey.

A bird that circles around a bright building, beam or illuminated complex is spending fuel it needed for forward migration.

U.S. Fish & Wildlife Service describes this repeated circling as a pathway to exhaustion and accelerated use of critical energy stores.

Even when the bird does not immediately collide, disorientation can leave it in an unfamiliar built environment where windows, traffic and other hazards become more likely.

Why Cloudy and Foggy Nights Can Be Worse

Light risk is not identical every night.

U.S. Fish & Wildlife Service specifically highlights low cloud ceilings and fog as higher-risk conditions. Birds may fly lower, natural visual cues become harder to use, and artificial light reflecting from clouds can create a bright disorienting glow.

That is why a cloudy migration night can deserve more attention than a clear night with little bird movement.

Spring and Fall Are the Main Lights Out Seasons

In North America, the largest migratory movements generally occur in spring as birds travel toward breeding grounds and in fall as they move toward wintering areas.

As a broad U.S. guideline, Fish & Wildlife Service suggests paying special attention to unnecessary lighting during April–May and August–October.

Those months are not precise universal dates. Migration timing varies by latitude, species and year.

For individual nights, tools such as BirdCast can help show when large movements are predicted or occurring across the United States.

The Best First Step: Turn Off Lights You Do Not Need

The most effective lighting reduction is also the simplest.

If a light is unnecessary overnight, turn it off.

Common candidates include:

• decorative façade lighting;
• landscape uplights;
• empty-room lights;
• roofline lighting;
• unused patio lighting;
• floodlights left on continuously;
• illuminated architectural features.

This reduces wildlife exposure and saves energy at the same time.

If a Light Must Stay On, Make It Work Harder and Spill Less

Lights Out does not mean every property must become completely dark regardless of safety or access needs.

Fish & Wildlife Service recommends using lighting only where and when it is needed.

Shield Exterior Lights Downward

A light aimed toward the sky illuminates far more than the walkway, door or parking area it was meant to serve.

Fish & Wildlife Service recommends fully shielded fixtures that prevent light from being emitted above the horizontal plane.

For a home, that generally means:

• the bulb should not be glaring directly into the sky;
• the fixture should illuminate the intended surface;
• light should not spill far into neighboring trees and habitat;
• fixtures should be mounted only as high as the job requires.

Use Timers and Motion Sensors

A porch light may be useful when someone arrives home but unnecessary at 3 a.m. when no one is outside.

Timers, occupancy controls and motion sensors reduce the duration of exposure without eliminating useful lighting.

Fish & Wildlife Service specifically recommends automatic controls as part of bird-conscious lighting.

Close Blinds and Curtains at Night

Indoor light can spill through large windows and contribute to the illuminated footprint of a building.

If a room is occupied at night, closing curtains, blinds or shades can reduce outward light without forcing people to sit in darkness.

This is particularly useful in upper stories, atriums and rooms with large expanses of glass.

Do Not Forget Interior Lights

Lights Out is sometimes interpreted as “turn off the porch light.”

Exterior floodlights matter, but so can bright interior lighting shining through windows.

Audubon’s Lights Out guidance recommends reducing interior lighting—especially on higher floors—or closing window coverings when people must work late.

Which Lights Should Be Highest Priority?

Does Light Color Matter?

Color and spectrum can affect wildlife responses, but for a homeowner the strongest first actions are usually simpler: eliminate unnecessary light, reduce intensity, reduce duration and keep light pointed downward.

Fish & Wildlife Service notes that some steady-burning red and white obstruction lights are particularly attractive to birds, and tower research has shown substantial collision reductions when unnecessary steady-burning lights are removed.

But do not let a debate over bulb color become a reason to leave excessive lighting on all night. A better-colored unnecessary light is still unnecessary light.

Lights Out Does Not Mean Sacrificing Safety

Lighting can serve legitimate safety, accessibility and security purposes.

The bird-friendly question is whether the fixture is doing more than the job requires.

For example, a motion-triggered, downward-shielded entrance light can illuminate a doorway when needed without broadcasting light into the sky all night.

The goal is better lighting, not indiscriminate darkness.

Why Glass Still Needs Its Own Fix

Turning off lights can reduce nighttime attraction, but it does not make reflective or transparent glass visible to birds during daylight.

Most building collisions occur at homes and low-rise buildings, and daytime glass hazards remain important even in a perfectly dark neighborhood.

OwlRatings’ window-collision prevention guide covers exterior patterns, screens and other treatments that make dangerous glass visible to birds.

Homes Matter, Not Just Skyscrapers

High-rise collision events get attention because hundreds or thousands of birds can be affected in a single night.

But Fish & Wildlife Service emphasizes that most fatal building collisions occur at homes and buildings under four stories because those structures are so numerous across the landscape.

That means residential action is meaningful.

You do not need to manage a downtown skyscraper to contribute to safer migration.

Apartment and Condo Residents Can Participate Too

If you do not control exterior building lighting, you can still reduce your own contribution.

• turn off unused balcony lighting;
• close curtains or blinds after dark;
• avoid decorative lights aimed outward or upward;
• use lamps or task lighting instead of illuminating the entire room;
• ask building management about migration-season lighting policies;
• report recurring bird collisions to management.

Collective reductions become especially useful in buildings with many illuminated units.

What About Porch Lights?

A porch light is not automatically a major migration hazard, but its design and use still matter.

If the light is needed:

• shield it downward;
• use only enough brightness for the task;
• put it on motion activation or a timer;
• avoid leaving it on from dusk to dawn without a reason.

If it is decorative and unused, switching it off is simpler.

What About Landscape Lighting?

Tree uplights, façade wash lighting and decorative garden spotlights often direct light exactly where bird-conscious design tries to avoid it: upward and into habitat.

If you keep landscape lighting, consider:

• downlighting rather than uplighting;
• lower output;
• shorter operating hours;
• timers;
• fixtures that do not illuminate the canopy or sky.

What About String Lights?

Low-intensity string lights are different from a powerful upward floodlight, but they still add artificial light to the night landscape.

Use them only when people are actually outside, place them low where practical, and switch them off afterward rather than treating decorative lighting as a permanent overnight feature.

What If Birds Are Already Circling a Bright Light?

Turn the light off if it can be done safely.

Fish & Wildlife Service recommends a 15–20 minute dark period when birds are entrapped around a bright source that cannot remain off permanently.

Audubon describes similar observations at New York City’s 9/11 memorial beams: temporarily switching the beams off allows bird density around the lights to fall quickly.

The lesson is powerful: lighting changes can have an immediate effect rather than requiring years to show a benefit.

Bad Weather + Heavy Migration = A High-Priority Night

If you want to prioritize rather than remember every night of the season, combine two questions:

1. Are many birds migrating tonight?
2. Are clouds, fog or other conditions likely to increase light attraction and lower flight?

A night with both heavy movement and poor visibility deserves especially aggressive light reduction.

Use BirdCast for Night-by-Night Awareness

BirdCast uses weather radar and forecasting models to estimate nocturnal bird migration across the continental United States.

Instead of relying only on broad “spring” and “fall” dates, BirdCast can help users see when migration intensity is expected to be high locally or regionally.

This is useful for:

• homeowners deciding when to be extra strict about lights;
• building managers;
• collision-monitoring groups;
• birders interested in migration timing.

Broad seasonal lighting reduction is still useful; forecasts simply help identify the nights when the potential benefit may be largest.

Lights Out Can Help Beyond Birds

Artificial light at night affects more than migrating birds.

Fish & Wildlife Service notes broader effects on wildlife and natural day-night cycles, while reducing unnecessary light also lowers energy use.

That means a lighting change can simultaneously:

• reduce migration risk;
• reduce skyglow;
• reduce unnecessary energy use;
• preserve darker habitat for nocturnal wildlife;
• restore more natural night conditions.

Do Birds Navigate Only by Stars?

No.

Bird navigation is complex and can involve celestial cues, Earth’s magnetic field, landmarks, polarized light and learned information depending on species and context.

So the Lights Out case does not depend on the oversimplified claim that every migrant is literally “following stars like a map.”

The relevant observation is that artificial light can attract and disorient night migrants regardless of the full navigation system involved.

Does Every Lit Window Kill Birds?

No.

Collision risk depends on building design, glass area, surrounding habitat, light intensity, local migration traffic, weather and other factors.

Lights Out is a population-level risk-reduction strategy, not a claim that every lamp directly causes a collision.

That distinction matters because practical conservation works by reducing avoidable risk across many homes and buildings.

Should You Leave Lights On to Help Birds See Buildings?

No. Nighttime illumination is not a substitute for bird-safe glass.

Bright light can attract migrants into the built environment rather than reliably teaching them that glass is solid.

If a pane is dangerous, make the glass visible with a proven exterior treatment and separately reduce unnecessary nighttime light.

A Simple Home Lights Out Plan

A Business or Office Lights Out Plan

Larger buildings have more opportunities for automated reduction.

• schedule nonessential interior lighting to shut off after workers leave;
• reduce lobby and atrium lighting overnight;
• turn off decorative façade and rooftop lighting;
• close blinds where late-night work continues;
• use occupancy sensors rather than entire-floor lighting;
• shield required exterior lighting;
• incorporate migration alerts into facilities-management routines;
• monitor for bird collisions around high-risk façades.

Common Lights Out Mistakes

How Lights Out Fits Into a Bird-Friendly Yard

A backyard can provide excellent habitat by day and still become unnecessarily bright at night.

A stronger year-round plan combines:

• locally native vegetation;
• less unnecessary lawn;
• clean food and water where offered;
• contained cats;
• safe windows;
• minimal pesticide use through IPM;
• dark, low-glare nighttime conditions.

See OwlRatings’ less-lawn habitat guide, bird-friendly pesticide guide and outdoor cats and birds guide for the other major backyard risk-reduction pieces.

Bottom Line

Lights Out works because many birds migrate at night and artificial light can pull them into dangerous, energy-wasting situations.

You do not need to eliminate useful lighting. Turn off what is unnecessary, dim what must remain, shield fixtures downward, use timers and motion sensors, and close window coverings when bright rooms are occupied at night.

Pay special attention during spring and fall migration, particularly on nights with heavy movement, clouds or fog.

Then treat dangerous glass separately. Darker nights reduce attraction; visible glass reduces collision risk. Together, those changes make homes and cities safer for migrating birds.

Sources & Further Reading

• U.S. Fish & Wildlife Service — Threats to Birds: Collisions (Nighttime Lighting)
• U.S. Fish & Wildlife Service — Threats to Birds: Buildings & Glass
• National Audubon Society — Lights Out Program
• National Audubon Society — Simple Solutions to Prevent Collisions
• BirdCast — Nocturnal Bird Migration Forecasts and Monitoring

Editorial note: Migration timing and lighting risk vary by geography, weather, building design and species. The broad seasonal windows in this guide are U.S.-oriented starting points; local migration forecasts and regional Lights Out programs can provide more precise timing.

Jonathan Gron

Jonathan Gron is the founder and editor of OwlRatings, where he researches birding, backyard wildlife and practical bird-safety guidance using current primary, government and professional sources.