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Check PriceIf you have pondered if your sparkling Christmas display has the potential to disturb the birds in your backyard display, you’re on the right track. The short answer, it depends on the types of lights, how and where they are placed, and when you turn them on. Here is what the science shows us, and what you can do about it.
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How Bird Behavior and Migration are Impacted By Artificial Light
The birds uses cues from natural light sources, but false light, or artificial lights, can disrupt their natural navigation systems. Bright lights that have a high concentration of blue light confuse migrating birds. The Cornell Lab of Ornithology and Lights Out have shown that bright artificial lights at night confuse and disorient birds and cause them to collide with windows that they can’t see, or to circle around and continue to hit lit buildings.
Migrating birds can become disoriented by certain urban light sources. During their migration, they use the moon, stars, and other natural light sources to freely travel without constraint. Urban light sources disrupt their natural navigation as they view the lights as navigational beacons. These urban lights draw birds into city areas and urban centers. Birds can get stuck in circles around lit areas while they try to find their way out. They can become exhausted from all of this circling and may crash into buildings.
A study that was published in Proceedings of the National Academy of Sciences in 2021 concluded that the increase of artificial light even in small amounts impacts the changes in both the routes taken for migration and the timing of such. Changes in artificial light during nighttime affect birds' hormonal cycles. These changes will impact when birds' migration starts and how their long-distance navigation is impacted.
It’s not only migrations that are affected by artificial light. Research shows that artificial light disrupts the circadian rhythm of birds. This affects when they sing and the way they forage. Also, local non-migratory birds that live near artificial light may start their dawn chorus earlier than they would otherwise. They may also change their sleep cycles and even their breeding behaviors.
Are Holiday Lights a Year Round Issue for Backyard Birds or Just During Migration?
Risk is not uniform. The most important factor is timing. The most important time frames include spring migration (April-early June) and fall migration (late August-November). These time frames have billions of migrating birds across North America. Nighttime lighting increases risk of collision and disorientation.
Holiday lights are put up in late November and December, which is about the time fall migration is ending. For most places, this means by when you put up the lights, the biggest risk of danger is over. However, the late migrators like some waterfowl and winter finches, are still moving during December. There are also challenges to resident birds.
Backyard birds are affected by the artificial light. However, the impacts are subtler than acute migration disruptions. For example, the birds that roost near the lit areas may have disrupted sleep. Given that sleep is critical for immune function, if birds do not get adequate sleep, they may forage less. Additionally, it is reported that the hunting behavior of nocturnal predators such as owls is also affected by artificial light. They may hunt near the light or avoid the light depending on the level of disorientation it causes in the prey.
Christmas lights are different from other types of lights because they are turned off during the night. Throughout the year, Christmas Lights are less stressful than street lights or flood lights because they are less intense, but are turned off for periods of time, so from time to time they can create stress for birds. During migration, stress from Christmas lights can combine with other extreme risks to make for stress for birds Christmas lights add year round stress. They are literally in the middle.
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Most and Least Harmful Types of Lighting and Setups
Not every holiday light display promotes bird safety in the same manner. There are a factors that plays a role in this, such as the brightness, color temperature, direction, and duration of the lights.
Brightness: Dimmer displays are preferred. Intense floodlights and searchlight displays are far more disruptive, compared to a simple string of small bulbs. If your display can be seen from a mile away, it is more likely to affect birds.
Light with color temperatures around 2700K is less disruptive than light at 5000K and above. Warmer whites and ambers disrupt less than cool whites and blues. 5000K and above lights are considered blue-rich and can suppress melatonin in birds. This can impact behaviour and disrupt cycles. For less disruption look for traditional incandescent bulbs and warm-toned LEDs.
Upward and outward pointed lights are the worst offenders as they create a glow that can be seen from high above and attracts or disorients passing birds. Lights that face downwards or are shielded by eaves, fences, or plants are much safer. When lighting trees, do not illuminate the entire tree's canopy and focus on the lower branches.
Risks associated with lights that stay on all night are greater than those with lights that are on timers. Most birds are least active from midnight to dawn. Turning off displays after 11 p.m. reduces impacts during times that birds are most active.
The research here is mixed and blinking or rapidly flashing lights may be more attractive to certain species of birds. In terms of overall safety, steady lights are considered more effective, but they are less effective than differences in brightness and color.
Bird-Friendly Holiday Lighting Steps You Can Take Tonight
You can leave your holiday lights up and protect birds by changing how you hang them.
Use a timer or set your lights to turn off by 11 p.m. or midnight. This single step cuts risk significantly and saves energy, too.
Use bulbs that are warm in color. Replace and cool white or blue LEDs with warm white, amber, or old-fashioned incandescent strands. Your display will still look cheery, plus you'll be helping the birds' circadian rhythms.
Aim your lights so that they shine down. For example, focus light on the ground, the front of your house, or lower landscaping and avoid illuminating trees or the sky. Use shielded fixtures or directional clips to keep lights in desired locations.
Lower the overall brightness. You don't need stadium-style lighting. Less strands or lower wattage bulbs can create a warm glow that is just as beautiful and less disruptive.
If you are decorating for the holidays in early November, look at forecasts for BirdCast to see which days will have the most migration in your area. If you see some peak migration nights, consider delaying or cutting back on your lighting for those periods. Also, check migration forecasts when setting up.
Please switch off the lights during the spring migration period. If you have lights and decorations that stay up into late winter/early spring, keep in mind that migration picks up again in April. Take down lights or keep them off during peak migration periods.
If you are lighting near glass windows, add window deterrents. Windows with lights are magnets for collisions. Decals, screens, or exterior netting can help prevent collisions.
It is the small changes that add up. Eliminating non-safe flyways and unhealthy habitats for resident species is possible by replacing your neighborhood’s lighting with bird-friendly options. With some intention, you can protect the birds you love while celebrating the season. Happy holidays and birding!
