When we think of sound, we consider many things such as talking, singing, humming, and music. Sound is an integral part of human culture, but animals rely on sound much more than we do.
Sound is key to an animal’s survival. Producing and hearing sound helps animals avoid predation, find food, and successfully rear offspring. There are two types of sound, vocal and mechanical. Verbal communication is through barks, purrs, growls, and hisses, whereas mechanical sounds are made by rubbing body parts together, such as grasshoppers or woodpeckers banging on a tree.
If you live in an urban neighborhood, you have likely heard dogs barking and birds singing. These are more than just noises. For animals, they are a vital aspect of daily life. How do animals produce sound? Does sound cross between species? Let’s find out.
How Do Animals Produce Sound?
There are two forms of sound production; vocal and mechanical. The respiratory system produces vocal sounds, and bodily contact makes mechanical sounds.
Mammals, birds, and some amphibians use vocal sounds to communicate. Dogs bark, frogs croak, and wolves howl. Sound is produced much the same as when humans talk, hum, or whistle. Air passes by the vocal cords, and as the air pressure changes, it vibrates, producing sound waves. Larger animals produce low-frequency sounds, and smaller animals produce higher frequencies.
Insects and some bird species use mechanical sound. These sounds are produced by rubbing body parts together or tapping body parts against a surface, such as a tree branch. Grasshoppers produce sound by rubbing their legs against their wings, which creates a sound similar to a chirp or flat whistle.
Fish are also capable of producing sound. They take air into their swim bladder, primarily for buoyancy, and quickly contract their sonic muscle. This causes the swim bladder to expand and contract, creating drumming sounds in short pulses.
Sounds made by marine animals tend to have an eery, otherworldly quality. This is because sound waves travel much further in water than in the air.
Some animals will call early morning and late evening when predators are less likely to hear, whereas nocturnal animals will produce sounds throughout the night. Owl hoots and cicada calls are common in rural areas of the United States at dusk and during the night.
Sound Communication For Courtship
Animals across all classes use some form of sound communication for courtship purposes. North Atlantic right whales use different sounds depending on the individual whale’s gender. Females will use short screeching calls lasting up to 2 seconds.
These calls are believed to be used to attract males or to announce their reproductive state. Males of this species produce sharp gunshot noises in response to the calls of nearby females or to warn off other males.
Male fiddler crabs, common along the Florida coastline, will produce clapping and honking sounds to attract females. The male crab will strike his claw into the substrate like a drummer would strike a drum to make this sound. They may also do this with their legs. Calls of this nature last from just a few seconds to several minutes.
Nearby male fiddler crabs will respond to a male rapping or drumming by producing a faster or louder call. Nearby males will also change their call to avoid being drowned out by another male.
Male frogs produce loud and impressive croaks to attract females. They have a sac below their mouth that they fill with air. As this air is forced out, it produces the distinctive croaking sound we all know so well.
The larger a male’s sac is, the more air he can take in and the louder croak he can produce. Females are attracted to the largest males who can produce the loudest croaks. The ability of females to hear the male’s call is also important. If a male’s sounds are reduced by thick vegetation or overshadowed by other noises, it may take females longer to find a mate.
Birds are the most well-known animals to use sound as part of their courtship ritual. Birdsong is a common feature of our lives, whether we live rurally or in the center of a busy town.
Males of most bird species will call to attract females. Some species can mimic the sounds of other birds. Females are attracted to the males who produce the longest and loudest songs, which shows he is strong and healthy.
Sound Communication For Danger
As we have already learned, male fiddler crabs use sound to court females. However, they also use auditory signals to warn other crabs of predators. The drumming or rapping sounds form a different pattern when used as a warning.
Bats have a unique way of using sound to their advantage. Although most people believe bats have poor eyesight, many larger bat species can see better than humans. Bats use echolocation to navigate their surroundings, find prey animals, and communicate with other bats.
Echolocation is when an animal emits sound and listens for the returning echo to judge the distance between obstacles and locate potential prey.
Bats also produce clicking sounds with their tongues to communicate with one another. If there is a potential danger or one bat is warning another to stay away, the variation of the clicks will change to suit the situation.
The most surprising use of noise when threatened comes from frogs. Most frog species can produce an ear-splitting scream when startled by a predator or other perceived threat.
The frog’s scream sounds very similar to that of a screaming child. The purpose of producing this noise is to scare or confuse the predator long enough for the frog to make their escape.
Many predators will ignore animals that produce loud noises, giving away their position to other predators who may try to steal the kill.
Unfortunately, animals rely pretty heavily on sound to communicate, and noise pollution from human activity has an adverse effect. Studies have shown that many bird species have changed the timings of their regular calls to avoid rush hour traffic. Other species sing louder to be heard above the noise of cars, trains, and aircraft.
Red deer and moose both rely on vocalization during the breeding season, and noise pollution can severely impact their reproduction success. This could come from aircraft, heavy machinery, or everyday traffic noise.
As humans expand further into the countryside, we are taking away from the habitat space of native wildlife. We are also harming their ability to find mates and reproduce.
Animals like bats and owls that rely on sound for hunting are also at risk as the noise pollution from human activity can fragment their hunting ranges. This means they have a smaller area to find food, which increases the chance of starvation and reduces their ability to reproduce.
For marine animals, the increase in boats, jet skis, and other watercraft has a similar impact. Finding mates and food is becoming more challenging and is even pushing some species closer to extinction.
Even protected national parks are at risk from surrounding road networks and planes flying overhead. Many experts have suggested no-fly zones or higher flight paths over protected areas to reduce intrusion on native wildlife.
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