How human noise pollution affects seal behaviour.
“Turn the music down, I have to concentrate!”
We have all heard someone say this while driving, and until you started to drive you probably thought this was a ridiculous request. Music couldn’t possibly hinder someone’s driving ability. But when you got your licence, you probably noticed just how distracting the radio can be. The same can be said for unwelcome noise when you’re studying, chatting with friends, or trying to enjoy a meal in peace. The fact is, we humans are noisy, and the impacts of our collective cacophony are affecting more than just one another; we rarely talk about how our noises might be distracting other animals.
As the world continues to observe declines in biodiversity, there has been a lot of attention brought to the detrimental effects of changing habitats on the survival of wildlife populations. Examples that often come up are how the melting sea ice has impeded polar bears’ hunting habits and how the damage to the great barrier reef has displaced many aquatic species. In most cases, the examples of habitat disturbance that we tend to think of are physical: things like “housing development, building roads, and spraying pesticides,” said Mackenzie Tuddenham, a fourth-year Mt. A psychology student. These are some of the more apparent contributors, but they are not the only threats to natural habitats.
Non-physical disturbance can also have a detrimental effect on species that have the bad luck of their habitats being too close to areas of human interest. Anthropogenic noise, which is noise created by human activities, has been shown to disrupt the behaviour of many types of wild animals.
For example, while hunting or searching for food, animals perform a series of risk versus reward assessments to aid them in their decision-making. The goal is to gain energy while using the least amount of energy, and to be able to get food while avoiding becoming food. This process comes from a concept known as optimum foraging theory. However, unnatural noise can affect an organism’s ability to conduct their decision-making process and result in them reducing their ability to successfully find food.
A recent study led by Dr. Gordon Hastie for the Sea Mammal Research Unit from the Scottish Oceans Institute explored the impact that anthropogenic noise has on seal populations. This research examined the foraging decisions and success of five seals in a captive environment. They compared the behavior of the seals when there was no sound disturbance present with their behaviour when the sound of machinery, like tidal turbines and pile drivers, were played. Their goal was to gain a better understanding of how human activities were affecting seal behavior.
The researchers found that when anthropogenic sound was present, the seals caught less prey and spent less time looking for prey that was harder to catch, compared to when they could forage without human noise. The researchers suggest that there may be several reasons why seals change their behavior in the presence of human-created noises. Foraging behavior is influenced by the perceived risk of predation, and the seals may rightfully see our noisy machinery as a risk. If so, they may be limiting their activity out of fear. Or perhaps the seals simply find these sounds unpleasant and struggle to concentrate in their presence. Either way, these findings suggest that human-created auditory disturbances are likely impacting hunting grounds for seals.
Mt. A biology professor Dr. Julia Riley shared her thoughts on why noise pollution’s impacts draw less attention from the media than habitat destruction. She said, “oftentimes, chemical pollution or habitat destruction is clearly negatively impacting something. I think that it is very visually impactful, so our attention is drawn to it, whereas with something like light pollution or noise pollution, oftentimes it’s less visually impactful and unclear what is causing an issue.”
To truly preserve natural habitats and safeguard our wildlife, all factors must be considered in our conservation efforts, not just the obvious physical threats. If we want to continue to see seals frolicking in the waters off our coasts, we must ensure that we are not impacting their hunting grounds; because when we are the ones making the noise, the animals cannot simply turn down the volume and concentrate.
For more information check out “Acoustic risk balancing by marine mammals: anthropogenic noise can influence the foraging decisions by seals” by Gordon D. Hastie and colleagues (2020).https://doi.org/10.1111/1365-2664.13931