From the major transportation infrastructures we use everyday of our lives, from highways to simple roads through the suburbs, we as humans may not notice the effects of a vehicle driving on a road. What is not noticed enough is the amount of anthropogenic noise produced from roads and traffic, and how this in turn effects the wildlife around us. How does anthropogenic noise effect our wildlife species, and how can we resolve this issue?
Roads & Traffic – Too Noisy?
Through human development, anthropogenic noise is introduced into the environment across multiple aspects of terrestrial landscapes; this includes, but is not limited to, airports, roads, and highways. Anthropogenic noise is known as a global phenomenon in today’s world, having the potential to impact wildlife species across every continent and habitat type.
Transportation systems are one of the most pervasive sources of anthropogenic noise across every landscape, including from sources such as roads and the traffic volume associated with it. Roads are very widespread and produce an increased amount of noise; though they may seem to cover a small surface area, the ecological impacts of roads and the noise associated with them extend well beyond a road itself. Anthropogenic noise from roads affects about one fifth of landscapes in the U.S., becoming problematic for wildlife due to the noise volume produced being very loud.
Anthropogenic noise also has varying characteristics that differentiate from the sources it comes from, such as the amplitude (or loudness), frequency (or pitch), and spatial and temporal patterns of the noise; this in turn determines the impact noise has on wildlife. This noise can affect wildlife both at an individual level and at a population level.
How Anthropogenic Noise Impacts Wildlife
On an individual level, wildlife are impacted by anthropogenic noise through the acute impacts noise can cause; these effects include physiological damage, masking of communication, disruption of behavior, and startling to an individual animal. Physiological damage to an individual animal can cause the animal’s inability to hear, either by permanently damaging the auditory system causing a permanent threshold shift (PTS) in the individual’s hearing, or by temporary reductions in the animal’s hearing sensitivity, known as temporary threshold shifts (TTS).
In terms of masking an animal’s communication, this happens when an animal perceiving a sound is impacted by the background noise (i.e., anthropogenic noise) and cannot make out the acoustic communication being relayed because it is masked. If this occurs, this will ultimately cause a decrease in acoustic communication between individuals or species. Acoustic communication is used by animals to attract and have mates, distinguish territory, promote social bonding, and alert others if a predator is nearby. If anthropogenic noise masks the acoustic communication, this can have dramatic effects on reproduction and survival of a species.
Anthropogenic noise can also cause an individual animal to suffer from chronic effects, such as elevated stress levels and associated physiological responses with it; this in turn can cause long-term welfare and survival consequences from anthropogenic noise effecting an animal.
Anthropogenic noise effects wildlife at a population level through how it can range from causing things such as population decline up to a regional extinction of a species. This is especially critical for species that are threatened or endangered due to habitat loss; if a species begins to avoid even more habitats due to anthropogenic noise, their status becomes more critical and could result in possible extinction.
Wildlife species have varied responses in their tolerability to anthropogenic noise due to their altered acoustic environments. For example, when a major transportation infrastructure is placed into an environment, studies have shown that the amount of species present near the road are greatly reduced from what they were before the road was placed; this majorly due to the road itself and the associated anthropogenic noise coming from it.
Anthropogenic noise coming from roads can also mask the communication of species, as stated above, and cause a decrease in their acoustic communication and in turn effect their reproduction and survival as a whole. However, how can we as humans reduce the amount of anthropogenic noise produced from our major transportation infrastructures to reduce the impacts it has on our wildlife?
Future Directions for Anthropogenic Noise
Though human development and the associated anthropogenic noise are rapidly spreading in our advanced world, there may not always be a logistically, politically, or economically feasible way to eliminate or even minimize anthropogenic noise altogether. However, there is a common approach that can be used, being to set noise standards for when major transportation infrastructures are implemented in hopes to limit the level of noise being produced into the environment. This would mean that when a road or highway is implemented, the noise production can be reduced either operationally or structurally to meet the noise standards.
An example of this can be shown through how road noise can be decreased by using specific types of asphalt, though this could also cause the road’s surface to have lower durability and traction. Another solution to reduce road noise could be to implement noise barriers along a road, however, these may also cut off migration routes and enhance rather than decrease the road impacts overall. So, how do we go about decreasing the anthropogenic noise imposed onto the wildlife around us?
Most of environmentalists researching this have discussed using a single noise standard that covers all anthropogenic noise situations; however, this does not account for all species and how the anthropogenic noise impacts each individual species. Rather than using a single noise standard, there should be a set of standards established that would be based off the measurement of sensitivities for species in specific concern or in a specific habitat location or type. If this set of standards were developed, this would be that wildlife would not suffer as much from the anthropogenic noise produced from human structures, while addressing how sensitive each species is to anthropogenic noise. We as humans don’t like hearing too much background noise and having it affect us daily, causing us things such as stress or not being able to effectively communicate with others. Why should let our wildlife be susceptible to this?
