Noise Pollution: A Harmful, Unseen Threat To Wildlife

Noise pollution, or environmental noise, is the propagation of noise with a range of consequences on human and animal life. Sources of outdoor noise are mostly caused by machines, transport, and propagation techniques. Noise pollution can cause harm to wildlife in several ways, including:

- Confusing organisms that rely on day and night cycles

- Interfering with essential nutrients in organisms' habitats

- Preventing animals from catching prey or escaping predators

- Increasing the body temperature of organisms to harmful levels

- Causing chronic stress, fertility issues, and changes in migration routes

- Impacting communication, mating, navigation, and foraging

Communication: Human-generated noise can drown out animal calls, disrupting their ability to warn others of danger, attract mates, or identify their offspring

Animals use sound to communicate, with many species developing distinctive calls to warn others of danger, attract mates, or identify their own offspring or packs in a crowd.

Soundscapes ecologists have found that different species within a habitat occupy distinct sonic niches, calling at different pitches or intervals than other species to ensure they are heard. However, human-generated noise, such as airplane engines, construction equipment, and lawnmowers, can easily

Mating: Noise pollution can reduce the effectiveness of mating calls, impacting population sizes and genetic diversity

Noise pollution can have a detrimental impact on wildlife, and mating is one of the key areas affected.

In many species, particularly birds and frogs, males rely on specific calls to attract mates. These calls are usually low-pitched, but in noisy environments, some males have been observed making their voices higher to compete with low-frequency noises like car engines. These less attractive vocalisations can reduce their ability to find and keep mates.

Additionally, noise pollution can cause mating calls to resonate through a smaller range, resulting in smaller breeding pools. This, in turn, can lead to a decrease in population sizes and genetic diversity.

The impact of noise pollution on mating is a growing area of concern for scientists, who have raised worries about its potential long-term effects on wildlife populations.

Navigation: Human noises can disorient animals that rely on echolocation, such as bats and dolphins, by damaging their hearing or causing them to adjust their calls

Noise pollution can disorientate animals that rely on echolocation for navigation, such as bats and dolphins. Echolocation is a biological form of sonar that allows animals to emit calls and listen to the echoes of those calls bouncing back from nearby objects. This helps them identify and locate objects in their environment, even in low-light conditions or without sight. Bats and dolphins are two examples of animals that heavily depend on echolocation for navigation and hunting.

Human-generated noise pollution, such as traffic or sonar, can interfere with the echolocation abilities of these species. The impact can be twofold. Firstly, excessive noise can cause hearing damage to these animals, impairing their ability to interpret echoes accurately. Secondly, noise pollution can force bats and dolphins to adjust the pitch of their calls, resulting in less effective echoes.

Bats, for instance, can modify their call intensity during echolocation, lowering the intensity as they approach objects that strongly reflect sound. This adjustment prevents the returning echo from deafening them. However, human-generated noise can overlap with the frequencies used by bats, making it harder for them to navigate and hunt effectively.

Dolphins also use echolocation methods similar to those of whales, producing short, broad-spectrum clicks at higher frequencies. While lower frequencies, or "whistles," are typically used for social communication, dolphins switch to higher-pitched clicks for echolocation. For example, the Atlantic spotted dolphin in the Bahamas communicates using frequencies ranging from 40 to 50 kHz but emits signals between 100 and 130 kHz when echolocating.

The impact of noise pollution on the echolocation abilities of bats and dolphins can have significant consequences on their survival and overall ecological balance.

Foraging: Loud environments can hinder animals' ability to locate prey, with potential knock-on effects on plant communities

Animals such as owls and cats have evolved complex ears to help them hear prey, but loud environments can hinder their ability to locate prey. A study found that for every 1dB increase in noise, owls were 8% less successful at catching prey.

Noise pollution can also have knock-on effects on plant communities. One study found that noise drew in nectar-eating hummingbirds, increasing pollination, but deterred several seed-eating birds, decreasing the spread of seeds. This indicates that noise may have the potential to alter a habitat's plant community.

In addition, noise can cause stress in animals, leading to fertility problems and changes in migration routes. Research has also shown that noise causes confined animals pain, fear, and cognitive problems. For example, in fish, vibrations from extreme noise can damage the swim bladder, impacting their hearing and buoyancy.

Noise can also interfere with basic activities such as movement, reproduction, and foraging. For example, some groups of sole have significantly increased their swimming speed when exposed to anthropogenic noises, and birds have moved to places with less vehicular traffic as the noise generated by traffic makes it more difficult to detect predators and conceal singing.

Overall, noise pollution can have significant impacts on the ability of animals to locate and capture prey, with potential knock-on effects on plant communities and the wider ecosystem.

Stress and anxiety: Noise is a source of stress and anxiety for many animals, leading to behavioural changes and cognitive issues

Noise pollution can cause stress and anxiety in animals, leading to behavioural changes and cognitive issues. It is an invisible cause of stress, posing serious risks to animal health and wellbeing. Research shows that noise causes pain, fear, and cognitive problems in confined animals. For example, vibrations from extreme noise can damage the swim bladder of fish, impacting their hearing and buoyancy.

Similar to humans, noise can cause mild irritation in animals, but it can also lead to more severe issues such as learning and memory problems and permanent hearing damage. In the case of lab rodents, loud noise has been shown to cause permanent hearing damage and change their behaviour, indicating that the noise may be physically painful for them.

Wild animals suffer from chronic stress and fertility problems due to noise, and they also change their migration routes. Captive animals, such as those in farms, homes, and zoos, are often exposed to high levels of human-generated noise that they cannot escape. This can lead to long-term fear and anxiety, as seen in dogs that exhibit fear responses to unexpected noises like thunderstorms.

Noise pollution can also affect the mating and reproductive behaviours of animals. For example, female frogs have more difficulty locating male signals in noisy environments, and noise can reduce the attractiveness of male calls, impacting their ability to find and keep mates.

Additionally, noise can interfere with the natural behaviours of animals, such as finding suitable habitats, avoiding predators, protecting their young, and establishing territories. Animals are forced to adapt to increasing noise levels, which can have detrimental effects on their health and survival.

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