Your Christmas lights could be causing a harmful ‘false dawn' effect for birds – here’s how to minimise their impact

It’s the season of twinkling Christmas lights, but for birds, that can lead to something known as the ‘false dawn’ effect.

Birds need plenty of energy to survive the colder months (that’s why it’s so important to know what to feed birds in winter), but Christmas lights can disrupt their sleep cycles during the longer nights and force them to spend energy out of hours.

I spoke to wildlife experts to find out exactly what the false dawn effect for birds is, the risks it carries, and how to avoid triggering it.

What is the false dawn effect in birds?

In a nutshell, artificial lights create what’s known as a ‘false dawn’, which wakes birds up in the middle of the night.

‘Many garden birds rely on daylight length to tell them when to sleep, wake and even begin courtship behaviour,’ explains Danny Yeoman, wild bird expert for Pets Corner and developer of Peter & Paul Bird Foods. ‘Artificial lights can confuse those internal clocks.’

When bright Christmas lights and other artificial lights are left on overnight, birds can mistake them for the first light of the morning. Sadly, that can mean they use up the energy they’d otherwise conserve for the daytime – even if you’ve left out shelter to keep wildlife warm over the winter.

‘This disruption can be harmful, as birds rely on natural light levels to regulate feeding, singing, and breeding behaviours,’ says James Ewens from wildlife shop Green Feathers. ‘When exposed to unnatural light out of hours, some bird species in turn use up valuable energy during the coldest, darkest hours.’

Some birds are more susceptible to the false dawn effect than others.

‘Robins are especially prone to it – they are one of the few species that regularly sing at night anyway – so a warm glow from fairy lights can gently nudge them into singing their hearts out at 2am,’ says Danny. ‘It doesn’t mean they’re distressed, but it does indicate their sleep-wake rhythm is being subtly disrupted.’

When the false dawn effect is triggered over and over again, Danny says, it can make it difficult for birds to conserve the valuable energy they need to survive freezing nights.

Luckily, there are a few ways you can reduce the risk of the false dawn effect without giving up outdoor Christmas lights.

1. Go for warm white lights instead

Cold, harsh outdoor lighting is more likely to cause the false dawn effect in birds – so it’s safer (and often much cosier) to go for warm white lighting instead.

‘Blue light mimics daylight most strongly,’ explains Danny. ‘Choose warm white rather than bright blue or white LEDs. As a rule of thumb, low, warm lighting causes minimal disruption, whereas bright, cool or flashing lighting carries a much greater risk of distortion.'

You can buy 25 metres of warm white outdoor fairy lights for £9.99 from Amazon.

2. Time it right

If your Christmas lights are very bright, it’s a good idea to turn them off around 9pm each night.

‘Birds are wonderfully adaptable, and for most, twinkly lights won’t cause serious harm,’ says Danny. ‘However, switching them off earlier will help your local birds get longer, uninterrupted rest, particularly during very cold periods when conserving energy is vital.’

Turning off your lights around 9-10pm is a thoughtful compromise, according to Danny.

‘That way, you still get the festive sparkle while also being kind to wildlife,’ he adds.

If, like me, you know you’ll forget to turn them off on the dot every night, there are plenty of outdoor lights that come with timers, like these outdoor warm white fairy lights from Amazon.

3. Keep lights away from feeding and nesting spots

If there’s one place you should never put a bird box, it’s right by outdoor lights – and it goes both ways.

‘Avoid placing lights on key shelter areas,’ advises James from Green Feathers. ‘Lights on hedges, trees or near nest boxes can be very disruptive as birds need these spaces for roosting and shelter.’

If you do decide to decorate trees or hedges with Christmas lights, it’s best to go for hedges with plenty of foliage (just make sure you check for nests first).

'Place lights in shrubs rather than bare branches,’ says Danny. ‘Leaves (even evergreens) help diffuse brightness.’

Winter essentials for birds

Stick to low, warm white outdoor lighting, keep them away from feeding and nesting areas, and try to turn them off before 10pm every night, and you'll halve the chances of the false dawn effect impacting local wildlife.