I’ve always thought that animals communicate similarly to the way humans communicate: one speaks, the other listens, the other responds. As a high school student, I often would find myself in the woods trying simply to escape from my reality and its stresses. Consequently, I found myself constantly listening to the different and fascinating noises of animals. I have always been interested in animal communication unknowingly, but I have never really considered the science of it. Looking deeper into the world of animals and their communication networks, I notice that these networks have far more depth than my natural intuition lead me to believe. Animal communication is an extremely vast and flexible system of senders and receivers. Multiple types of animals can adapt to certain environments to produce optimal signals. Certain species of animals even have elements of human communication to improve signal reception. After doing much research on the efficiency of these systems, I wondered, what could the flaws possibly be? This train of thought lead me to thinking about younger years in the swamps and woodlands of Tallahassee, Florida. I recalled the bullfrogs on the edge of a lake nearby being extremely noisy throughout the nighttime. One early morning when my friend and I set out to go fishing on the same lake, we witnessed a water moccasin, an extremely deadly and poisonous snake native to Tallahassee, swallow one of these bullfrogs. Was it the sorry frog’s signals that eventually led to its own death? What other ways is animal communication harmful to the two parties participating? First, one must understand the foundation that animal communication is built on.
To create a platform on which I can describe the problems within animal communication, I firstly want to explain the fundamentals of the art. To understand signal interference, one must first understand the signals themselves. Signal Detection Theory is the basis of almost all animal communication. In nearly all forms of animal communication, there is a distinct sender and receiver. The sender emits a signal for the receiver to interpret. A signal is defined as something that merits a response. If one animal clearly receives a signal from another animal, the receiver must show an observable response, whether it is subtle or blatant. Despite the importance of the sender, the majority of the burden is put on the receiver.
Signal detection theory states that there are four possible outcomes to a signal reception: correct detection, failed detection, correct rejection, and false alarm. If an animal correctly detects a response (correct detection), it will realize either a potential threat or mate in the area. Failed detection, on the other hand, is the failure to detect a potential threat or mate. Correct rejection is the realizing of a suboptimal mate or threat in an area, while a false alarm is the response to a suboptimal threat or rival (Brumm, 2013, 8-12). Sometimes signals are totally ignored within a species. For example, juvenile California ground squirrels and vervet monkeys’ signals are often completely ignored for a just reason. These juvenile creatures emit warning signals when there is no need to, so the older members of the groups adapt to ignore these signals (Kaplan, 2014, 91-92).
Not all animal communication is limited to this four-outcome table, however. Other forms of communication come in forms of gestures and non-verbal communication. Researcher, Gisela Kaplan, discovered that these gestures were used not only in primate communication with their hands and arms, but also unpredictable animals such as the Australian magpie. These birds point their beaks at a potential predator until the entire pack realizes the threat (Kaplan, 2014, 98-100).
Another unusual, and quite possibly the most astonishing, means of animal communication is by elephants. Until fairly recently, most scientists concluded that elephants communicate only in the range of human hearing capabilities. Katy Payne’s research has debunked this claim. By sitting next to elephants for extended periods of time, she began to feel a certain irregular vibration. With more advanced equipment, Katy Payne discovered a low frequency signal between elephants that humans are unable to hear. This form of communication is so unique and so effective because low frequencies travel much further than high frequency signals, giving elephants the ability to communicate miles away (Katy Payne, “Elephant Songs”). Different animals adapt to make their communication as effective as possible, but what are the factors that these animals must overcome to communicate? What is getting in the way of fail-safe animal communication? In many cases, the answer is noise.
For the purposes of this paper, noise is defined as any sound within an environment that is not the signal being detected by a receiver. For example, if a frog sends out a signal in a marshy lake to another frog, the sound of the wind, the water, the other animals’ signals, and other animals’ unintentional sounds would constitute as noise. In a real world environment, noise is almost always inevitable. Marc Naguib explains the most outright consequence noise has on communication as “the most straight forward effects of noise occur when the noise is actually masking the signal. A low signal-to-noise ratio will directly reduce the probability of detecting and recognizing a signal, leading to errors in communication” (Naguib, 2013). Noisy environments also raise other issues for animals trying to communicate. Naguib, discusses that noise can affect not only the signal itself, but also the mental state of the receiver. He elaborates,
“Noise disturbance, moreover, can affect attention and cognitive performance, a vital component of communication… Animals require attention to various environmental stimuli and such cognitive load can involve more than one sensory modality. Attention generally needs to be divided up, depending on the urgency (Parasuraman, 1984; Dukas, 2002, 2004; Chan & Blumstein, 2011), and noise can influence these attentional processes. In order to make use of information in a signal, a receiver not only needs to be in hearing range of the signal and able to detect and recognize it, it also needs to be sufficiently attentive to the signal, to memorize relevant information as well” (Naguib, 2013). Naguib goes into further detail about the way certain amplitudes and frequencies of noise can be more distracting than others. Much like humans, if a noise is steady, animals will adjust and divide their attention efficiently. If a noise fluctuates and can not be predicted, animals are more distracted and are far more likely to lack the attention to properly detect a signal.
Another trouble with animal communication is a third party receiver intercepting a signal. Many predators use this to locate a potential prey by hijacking the sound to determine the prey’s position. William Searcy, a scientist and researcher at the University of Miami, reports such interactions between crickets and geckos. Male crickets let off their mating calls while geckos sneakily follow this signal to the location of the cricket. An extraordinary example of this interception can be seen with the tungara frog. Tungara frogs’ mating calls end with a series of ‘chucks’, which are dependent on the size of the frog. Female tungara frogs tend to respond to mating calls with lower pitched chucks. This system in which pitch of mating calls corresponds to size of frog cannot be faked. It takes more energy to produce a lower pitched call, and Tungara frog’s size is directly correlated to it’s potential energy for producing a call. Thus, it is a true vocal system to display a tungara frog’s size. Unfortunately for these bigger frogs, fringe-lipped bats, their natural predator, can also hear these chucks and are more inclined to approach a frog with lower chucks. The bats intercept multiple frog signals and find not only where their prey is, but also which is the most optimal prey to consume (Searcy, 2005, 182). Noise and other factors have proven to hinder animal communication, but likewise multiple animals have found ways to adapt to it.
Certain animals have found different ways to deal with habitat noise and other signal-altering factors. For example, a sender can manipulate its signal to increase the probability of a successful reception by the receiver. A sender must consider four things when creating a signal: the frequency, energy or amplitude, directionality, and the point of origin. (Pijanowski et al, 2011). Species can also use a visual warning signal in places that have low visibility and high noise to prompt a more audible information-based signal being sent. This allows the receiver to prepare to take in an informational signal. A great example of this technique is the Anolis lizards’ communications. Scientists, Terry Ord and Judy Stamps, conducted an experiment in which a robotic lizard played its mating call with and without the preemptive warning signal. The Anolis lizards’ warning signal is characterized by a pushup motion. Results of the experiment showed that lizards responded more quickly when the alert signal was emitted before the mating call than just the mating call alone (Ord and Stamps, 2008).
Certain animals obtain a special ability dubbed ‘the cocktail effect’, which is the special adaptation to single out a certain audible signal, even when there is a heavy load of background noise. One observable example of this cocktail effect is observed within king penguin colonies. Juvenile king penguins must find their parents in a colony of thousands of penguins by detecting their call. Aubin and Joventin experimented with baby chicks by using a speaker to replicate the parent call and the surrounding background noise. In a young penguin’s natural environment, the background noise and other adult calls should drown out and distort the signal of the parent penguins. Young juvenile king penguins, however, always seem to find their parents even in the noisiest, most unforgiving circumstances. (Aubin and Jouventin, 1998).
Studying animals and their communication can do more than just explain the way penguins find their mother or other species alert their tiding of danger. Many of these animals have communication abilities that humans don’t possess, and we have the amazing opportunity to learn from them. By observing the way noise and other factors affect communication, we can also comprehend certain animals and ecosystems relationships to one another, whether it is a predator-prey or mutualistic relationship. Animal communication opens the doors to understanding more about the unseen or unheard relationships between and within different species.
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