Noisy Humans Make Birds Sleep with One Eye Open

Noisy Humans Make Birds Sleep with One Eye Open – But Lockdown Offered a Reprieve

Sleep is essential for humans, and it’s no different for animals. While we often think of sleep as a human-specific need, many animals, from insects to primates, experience a state of reduced awareness at some point in their day. But why do animals need to sleep, and how do they manage to get some shut-eye in a world filled with predators and distractions?

In our latest study, we explored the sleep behavior of the Eurasian oystercatcher, a well-known British wader that commonly sleeps on the ground at high tide in large groups. We found that these birds adjust their vigilance depending on what humans are doing nearby. When walkers pass within 150 meters of their roost, the birds keep their eyes open for significantly longer, particularly if the walker has a dog. It seems that dogs are a real and unpredictable threat that the birds need to actively monitor.

Meanwhile, passing boat traffic means the oystercatchers peek more times per minute, but each peek is much shorter, suggesting that boat noise is a regular disturbance, but one they’ve learned to feel less threatened by. We also found that sleeping birds alter their vigilance depending on the size and behavior of their social group. If there are more birds around them, they peek less often. Safety in numbers – with more eyes watching for danger – clearly means more rest. But if more of the individuals surrounding the observed bird are awake and alert, then peeking significantly increases, suggesting it pays to keep an eye on your neighbors.

The importance of sleep for animals cannot be overstated. Animals that are more vigilant and regularly disturbed sleep less and use up more energy, which can harm their chances of survival in the long run, particularly during the winter season when food is scarce and conditions are harsher. UK oystercatcher populations have declined by around 35% over the past 25 years, and they are listed as near threatened by the International Union for Conservation of Nature (IUCN). One of the key threats they face in the wild is the noise and disturbance of humans in their coastal habitats.

So, how might the months following the onset of lockdown in the UK have helped? The sudden and dramatic reduction in human activity led to goats reclaiming Llandudno in Wales and deer wandering the streets of East London. Animals in more rural locations are likely to have benefited too, particularly as this sudden drop in the number of humans outdoors coincided with the breeding season for many species, including the oystercatcher. The strange calm would have allowed these animals to focus their efforts on raising young, rather than monitoring humans and their dogs.

It’s too early to tell whether this will translate into an increase in numbers in 2020 and beyond. Indeed, we don’t know if a reprieve of just a few months is enough to make a difference, particularly for wildlife declines that have been ongoing for decades. Perhaps one thing we have learned, though, is that silence really is golden for many of the wildlife species we regularly encounter.

Conservation After Lockdown

As we move forward, it’s essential to consider the impact of human activity on wildlife. The UK’s coastal habitats are a critical area of focus, as they are home to many species that are vulnerable to disturbance and noise pollution. By reducing our impact on these habitats, we can help to protect the wildlife that calls them home.

FAQs

Q: Why do animals need to sleep?
A: While we don’t fully understand why animals need to sleep, scientists believe it has to do with conserving energy, repairing and maintaining the central nervous system, and regulating the connections between nerve cells to ensure they can process information more effectively.

Q: How do animals manage to get some shut-eye in a world filled with predators and distractions?
A: Many animals have developed unique adaptations to help them sleep safely. For example, birds like the oystercatcher have developed “peeking” behavior, where they open one eye intermittently and keep half of their brain active to monitor their surroundings.

Q: What is the impact of human activity on wildlife?
A: Human activity, such as noise pollution and disturbance, can harm wildlife by disrupting their sleep patterns and increasing their energy expenditure. This can have long-term consequences for their survival and well-being.

Q: How can we help protect wildlife?
A: By reducing our impact on coastal habitats and minimizing noise pollution, we can help to protect the wildlife that calls them home. Additionally, supporting conservation efforts and raising awareness about the importance of wildlife conservation can also make a difference.