Noise Pollution Affects the Reproductive Process in Bluebirds

Specialists have proved that noise pollution affects birds, disrupting their reproductive process. When the species known as bluebird chose her home near a natural gas compressor, this little creature did not know what was coming next. The sound of the machinery makes it harder for birds to hear when predators approach. Therefore, the stress hormone levels have increased. The health of this little creature has been affected.

Scientists wanted to know exactly what the bird experienced when living near that natural gas compressor. Therefore, they have developed a study where they sampled blood. The test was part of a study of 240 nesting sites located near the natural gas treatment plants in northern New Mexico. The results they have revealed were striking. The little bird experienced the same physiological symptoms just like a person suffering from a post-traumatic stress disorder.

Rob Guralnick is an associate curator of biodiversity informatics at the Florida Museum of Natural History. He argued that the noise causes these birds to be extremely stressed out. This has an unprecedented effect on their state of health and their offspring. However, maybe an avian psychologist needs to evaluate these birds to conclude whether the noise really hurts their mental health.

Western bluebirds suffer due to human-made activities

Guralnick published the new paper on January 8th in the Proceedings of the National Academy of Sciences. Together with his colleagues, Guralnick argues that there must be a link between the unusual levels of stress hormones, noise pollution, and decreased survival rates. In a population of wild animals, this represents the first time when scientists establish this connection.

He also claims that when animals change their environment, usually they experience habitat degradation. However, in this case, it is about an acoustic degeneration of the environment. Therefore, this transforms into a real conservation concern. Scientists have conducted this research at the Bureau of Land Management’s Rattlesnake Canyon Habitat Management Area. This site is not inhabited. However, there are a few compression stations and natural gas wells.

These emit a continuous hum, almost in the same range as various birds’ songs. Hence, this site is the perfect place to examine the effects of human-developed noise especially if the area is not inhabited. Clint Francis is an ecologist at California Polytechnic State University. He has been analyzing this ecosystem for over ten years now.

In previous researchers that he has developed, Francis indicated that the noise could alter the entire structure of certain communities, forcing birds to produce different songs, in a higher pitch. Furthermore, this also influences the distribution of plants relying on what birds remain. Furthermore, some species appeared to react better when they have nested near noise sources. In this way, all that noise managed to keep away predators.

A western bluebird

Specialists have analyzed the impact of noise pollution on western bluebirds and their offspring.

Noise pollution prevents them from hearing predators

Francis also says that he and his team are concerned about the reproductive process of this species of birds. This is the main reason why they wanted to look at the stress hormone. The blood tested showed that the corticosterone levels were lower than normal for birds which live closer to the gas compressors. Researchers were actually surprised by this result.

Corticosterone represents the equivalent of cortisol for birds. This is the hormone which triggers the release of adrenaline in the body. They asked for Christopher Lowry’s opinion on these results. Christopher Lowry is a stress physiologist at the University of Colorado at Boulder. They were not surprised by Lowry’s opinion who argued that it is normal to see these results in a bird exposed to persistent noise.

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When suffering from chronic fatigue syndrome or PTSD, humans’ response is to mute the hypothalamic-pituitary-adrenal (HPA) axis. This represents a cascade of chemical responses that stress triggers. Lowry explains that the birds are in a continuous state of hypervigilance and constant arousal. After a certain period of time, the physiology adapts in order to conserve resources.

The diminishing of the HPA axis is related to an overall decline of the state of health. In this scenario, a human would experience some cardiovascular issues, extreme fatigue, and gastrointestinal problems. However, the western bluebird, known to be tolerant to noise, had damaged feathers. Its body was slowly breaking down.

Western bluebirds have unusual stress levels

Lowry highlights the fact that humans and animals have similar responses to stress, suggesting that this type of response dates back ancient times, being deeply ingrained. To have a full auditory experience is extremely important for optimal health in both birds and humans. Francis indicates that hearing has to do with our ability to sense the dangers that may be around us.

On a constant basis, animals survey their surroundings, to make sure there are no predators. Noise pollution degrades this crucial sensory channel. Exposure to loud noises can diminish an animal’s ability to rely on listening to dangers or use sound. Therefore, for these birds, risk assessment can become really uncertain, leading to anxiety.

Nevertheless, Francis argues that it may be hard to really prove that bluebirds living near factories suffer from anxiety. There are numerous interconnected factors which may contribute to the unusual levels of stress hormone. However, specialists cannot tell for sure whether western bluebirds are stressed due to the noise or because they are unable to hear predators.

The information the scientists have accumulated indicate that there is a Goldilocks distance from those natural gas compressors where the birds are better off. They believe that the loud noise will scare the predators. However, the birds are unaware of the risks the loud noise poses to the offspring. The chicks only have a few feathers, and they do not seem to have proper development. To be able to solve the mystery, specialists need to come up with a lot of experiments.

Summing up

Human-made actions damage the habitat of innocent creatures. Western bluebirds are affected by noise pollution near factories. Their reproductive process is impaired, and this environment also impairs their health. Tests proved that they have abnormal stress levels as if they always feel that they are in danger. Due to the loud noises, they cannot hear predators approaching. Their offspring’s health is in danger, and the entire species suffers.

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William E. Eubanks
 

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