Speed, pitch and tone – how we sound can allow receivers to pick up pretty reliable indications on our mood, gender, age and probably physical traits like height and weight!
Generally, a taller individual has lower and wider airways that create a lower-pitched sound. This ‘deeper voice’ detail helps the listener to build a mental image and determine his or her height without even seeing the caller! Vocalisations like growls, howls, and songs are important and widespread for communication in the animal kingdom.
Hearing Different Sides of A Call
There is so much to explore with an animal’s sound! On top of broadcasting its exact location and for the receiver to gather information on its identity (like age and sex), vocalisations also serve to aid group recognition, establish or show dominance and submissiveness within a group, act as warning calls against dangers, maintain an animal’s turf and to attract mates.
Some species of animals might appear silent just because we cannot hear them! A typical adult human can detect sounds of frequencies between 20 to 20,000 Hertz (those lower than this range are infrasound while those above are ultrasound). If only our ears are equipped to pick up both infrasound and ultrasound, we will be serenaded by an extensive and delightful repertoire around us.
Slipping Under the Human Radar
We are quite familiar with the trumpeting calls of elephants. What’s inaudible to us are the rumbles that are rich in infrasound. These low frequency sounds have longer sounds waves which allow calls to be carried across long distances and around obstacles without being absorbed or reflected by the environment.
Asian elephants trumpeting. Source: SeaWorld
Such long-distance ‘messages’ make it a breeze for elephants to coordinate movements over vast areas among the family group members. They also use it to communicate, exert their dominance or compete for food resources in the presence of other elephants.
Asian elephants also emit infrasound rumblings to indicate that they are receptive and ready to mate.
Spanning the other end of the spectrum that’s beyond the upper limit of human hearing, high frequency ultrasound is produced and detected by some species of rats, bats, toothed whales and other marine mammals for communication with each other. They use ultrasound to detect prey (via echolocation) and for navigation in areas with low visibility.
Lucky for us, we can still detect and appreciate many animal sounds and calls within our hearing range. Here is a selection of 8 quirky and unexpected calls from the resident critters in our parks.
1. Giant Anteater – Hardly the most vocal animal in town
Usually quiet while going on its solitary life, the magnificent giant anteater does emit a ’braying’ sound when alarmed. Most of their communication occurs between the young and its mother or when they are fighting with each another.
Giant anteaters bellowing and braying. Source: SeaWorld
Expect to hear snorts, sniffs and hisses during such tussles! Giant anteaters use their long fore claws (around 10 cm long) to fend off natural predators like jaguars and pumas, though they will prefer to take flight than resort to that!
Visit them at: River Safari, Amazon River Quest
2. Barn Owl – They don’t really give a hoot
If you hear hoots at night, it is certainly not the barn owl. A barn owl communicates using a collection of low raspy sounds, chatters, hisses and shrieks. The characteristic deafening and harsh shriek is usually employed to send a strong ‘keep away!’ message while a long hiss is made to deter predators that intrude its nest.
Usually vocal, the barn owl does know when and how to be quiet. It is able to achieve silent flight and approach its prey undetected, all thanks to its lightweight frame and broad wings with specialised fringe feathers to muffle any sound of its movement!
The barn owl is able to hunt in complete darkness with its superb low-light vision and acute hearing. We are not taking a dig at its concave facial disks but they aid in funneling and magnifying sounds to the birds’ ear so that the owl can pick up very faint calls by their prey!
Visit them at: Jurong Bird Park, World of Darkness
3. Spotted Hyenas – Laughter is the best weapon
Well-known for their shrill laughter and capable of making up to ten unique types of call, the spotted hyenas are definitely an expressive bunch. Spotted hyenas live in clans of 10 to 90 individuals and the unique laughter of each individual help to establish its social rank within the clan.
Spotted hyena clan cackling. Source: Sound Bible
It has been established that the pitch of the giggle reveals the hyena’s age while changes in the frequency of notes reveals dominant or subordinate status of the animal. Spotted hyenas also use laughter to rope in allies when they go for a large kill. Well, talk about laughter that brings hyenas together!
Visit them at: Night Safari, Tram Safari
4. Siamangs – Winners of the best love duet
Being highly territorial, siamangs mark their turf vocally by singing in tune with each other. Female will usually take the leading role by ‘singing’ first.
Siamangs are monogamous (one mate for life) and the duet serves to keep their territory and also to maintain their pair bonding. Their enlarged throat sac, that can be as big as a human head, works like a speaker to further amplify their loud vocalisations!
Visit them at: Singapore Zoo, Treetops Trail
5. Common Brushtail Possum – Scaring the daylights out of Australians since a long time ago
Other than being the most widely distributed and abundant marsupial in Australia, the common brushtail possum is also one of the most vocal marsupials. Its nocturnal and tree-dwelling nature while foraging has left many locals wondering what animal it is that makes such a sinister call in the middle of the night.
Its deep rattling calls are used to broadcast their territory range and to attract mates during breeding season. They also communicate using click, grunts, hisses, coughs and screeches!
Visit them at: Night Safari, Wallaby Trail
6. Red-bellied Piranhas – Meet the new grumpy
Notorious and known to be man-flesh eaters (they are not), the aggressive red-bellied piranhas are definitely the most unlikely candidates to study underwater vocalisations. Enduring potential finger nips, brave scientists have identified three distinct types of sound, including croaks and barks while feeding or handling them.
These sounds are not produced by vocal cords and instead, caused by a tensing of the muscles linked to their swim bladder (an air-filled organ to maintain buoyancy). By changing the frequency of the muscle contractions, the piranha can alternate the sound between a croak and a bark. These hostile sounds are emitted as a warning to fellow piranhas in the shoal. While they appear to live and move in shoals, they do not hunt in an organised manner and are potential competitors for food.
Visit them at: River Safari, Amazon Flooded Forest
7. Cheetahs – The chirpy one
Cheetahs cannot roar like some other big cats but it certainly packs a rich repertoire of sounds including purrs, bleats, hisses and barks. What‘s noteworthy and unique to cheetahs are chirps that can be heard up to 1.5 km away!
Usually emitted by females with cubs that wandered off, cheetahs temporarily separated from their partners have been observed to chirp continuously until they are reunited. Cubs also make such high-pitched chirping sounds to deceive and avoid natural predators (lions and hyenas) when their mother leaves the den to hunt.
Visit them at: Singapore Zoo, Wild Africa
8. Greater Racket-tailed Drongo – The songbird that recruits and deceives
On top of its call list that consists of whistles and trills, this forest-dwelling species has a striking ability to imitate the calls of other bird species that share its natural habitat. Greater racket-tailed drongos are insectivorous and they hunt in feeding parties made up of several species of birds. By mimicking them, the calls help to attract and invite them to come together to forage for insect prey.
While other birds are busy foraging, drongos sometimes act as sentinels to watch out for predators. When it spots a predator entering the party, the drongo mimics and sounds off the alarm calls of other birds which incite a response to attack the intruder! From time to time, the greater racket-tailed drongo imitates calls of birds-of-preys to alarm the birds in the feeding party before it swoops in to devour the insect prey that have been abandoned. Sneaky.
Visit them at: Jurong Bird Park, Wings of Asia
Tuning Out To Tune In
The next time when you are out for a ramble in our parks, do tune out from the handheld gadgets and admire the rich repertoire and action around you. The animals are definitely calling for a purpose.