The Sound of Amazon Flooded Forest
Flying over a never ending sea of green! Over the unimaginably vast and densely dispersed canopy, too grandiose to be real to my eyes! Over the horizon, where the green was fading into the sky blue, the glaring mighty Rio Amazonas was zigzagging gracefully through the rainforest, like a massive silver vein spreading evenly throughout the land feeding various life forms. What a beauty! La Amazonia. The name Rio Amazonas was given by Francisco de Orellana a Spanish explorer and conquistador after his 16th century expedition was attacked by native warriors. Warriors were led by women, reminding Orellana of the ‘Amazon warriors’, the warrior women of Assyria (Asia Minor). The root of the word Amazon comes from Greek mythology; “a race of female warriors related to Iranian Scythians and Sarmatians,” probably from an unknown non-Indo-European word, or possibly from an Iranian compound *ha-maz-an- “(one) fighting together. [1]“Apollonius Rhodius, Argonautica, Book 2”. Archived from the original on 30 August 2017. Retrieved 15 October 2018. Amazon etymology[2]https://www.etymonline.com/word/amazon
My destination was Leticia, a small town with a population of approximately 50 thousand inhabitants on the banks of Amazon river located at the point where Colombia, Brazil and Peru come together in an area called Tres Fronteras. Leticia is one of the thousand cities located in Amazon basin, with around 6.3 million km2 of are shared between 8 countries, about 5.5 million km2 of which is covered by tropical rainforest, the largest in the world. The only way to get to Leticia from Colombia is by air, as there are no roads connecting further into department of Amazonas, but from Brazil or Peru one can take a boat through Rio Amazonas. Out of the airport, the first thing that drew my attention was the unique soundscape of Amazonia. The constant immersive sound of cicadas, crickets, frogs and birds of diverse variety hit my eardrums hard. The powerful surround sound that was omnipresent in the space, like a mist or a shape shifting cloud that embraced my body and soul.
Here we are in Leticia. After a quick search, a nice Peruvian guide offered us to stay with his small community located 20 kilometers from the town in the heart of Amazon flooded forests on the Peruvian side. After a few hours of a pleasant ride on his tiny boat we arrived at a small settlement with around 300 residents located on the bank of a river branched off from the main Amazonia. The settlement was almost entirely on stilts. Some sort of poles or posts that allow a structure to stand at a height above the ground. This part of Amazon is almost completely flooded during the six-month wet season. By April, the end of the rainy season, the river rises up and overflows its banks. As a result, all living things in the forest, including locals, must adapt to this kind of environment. After settling down, our guide who had noticed my desire of sound asked if we want to hear the voice of the forest! I could see a flash in his eyes while proposing this. We accepted without hesitation, and he continued ‘this is a place my brother and I usually go to at night to meditate and listen to the voice of the forest’. it’s quite amazing how these locals are connected and dependent on the sound of their habitats like our ancestors used to do. I can’t explain how exited I was and yes! That night, that immersive ancient soundscape of the Amazon flooded forest became a landmark on my memory. It was around 10 pm, May 20, 2018. We got on that small wooden boat and rode for about half an hour through the dark narrow passages of the flooded forest until we entered a wider branch of the river covered with high and dense trees and bushes on both sides, so dense that it sounded like a reverberant space. I put my stereo rig at the tip of the boat, four of us sat in silence, opened our ears and let the river current take us through the hundreds of thousands years of audio story of life evolution.
✔ note: A moderately quiet place and quality open headphones are recommended for an optimum listening experience.
As it can be seen in spectrogram view, Amazon forest hosts the richest biodiversity on the planet earth. The high density of the living creatures fighting for the space is clearly noticeable in the time-frequency spectrum. Finding a clear noise-free bandwidth to transmit and receive information within this compact acoustical environment is a crucial survival skill. A skill acquired through hundred thousand years of co-existence in a shared habitat. One of the more robust generalizations we can make about animal sound communication is that small animals usually communicate with high-frequency sounds and that larger animals tend to use low-frequency sounds. This general law is due to physical limitations of a signaler and efficiency on radiating and propagating communicational signals as well as safety issues.
On the signal production side, it is difficult for an animal to produce an intense sound with a wavelength more than twice its body dimensions. Many animals produce sounds with wavelengths longer than their bodies, but the cost is an increasingly rapid drop in the efficiency of sound radiation, and thus in sound intensity. However, radiation efficiency drops off faster with increasing wavelength than propagation efficiency does. For wavelengths more than 2-3 times the size of the signaler, radiation losses will outstrip any propagation benefits. Such observations support the notions that there is a minimal frequency that an animal can use for long-distance communication, and that this limit is inversely correlated with the signaler’s body size.[3]Bradbury, J. W., & Vehrencamp, S. L. (2011). Principles of Animal Communication (2nd ed.). Sinauer Associates is an imprint of Oxford University Press.
Infrasound signals are usually used to communicate over long distances like hundreds of miles in the case of whales or the Sumatran rhinoceros that has been shown to produce sounds with frequencies as low as 3Hz [4]von Muggenthaler, Elizabeth (2003). “Songlike vocalizations from the Sumatran Rhinoceros (Dicerorhinus sumatrensis)”. Acoustics Research Letters Online. 4 (3): … Continue reading. In our audio spectrogram there is no bioacoustic signal below 170Hz. From there up to around 1.2kHz there are signals possibly belonging to various large birds who vocalize by movement of fluid medium (air) against body part (respiratory system). On 5:20 in timeline I have no clear idea weather this signal belongs to a mammal or a large bird! but all are using mentioned vocalization method. From 1.2kHz up to around 3kHz is shared by birds and larger amphibians like tree frogs or possibly large insects that are producing short chains of pulsation and percussive signals in various combinations. From 3kHz up to 9kHz we are entering into the realm of insects of various sizes which are producing signals with means of moving body parts within fluid (water or air) or against another solid. Methods such as stridulation, buckling and fanning that generate narrow-banded continuous audio signals who can be seen as various long and thin parallel lines as well as various methods of producing short non-continuous signals such as Percussive striking, pulsation and fluid compression. One should be aware of many species of birds, mammals and amphibians that are also capable of producing such signals within these bandwidths using same methods. Up from 10kHz belongs to tiny insects and other creatures like bats and dolphins, who are capable of producing very high frequency chirps and clicks. The generated frequency over human audible range (20kHz) falls into the category of ultrasonic signals that can be used in navigational system (echolocation or biosonar) to orient and to capture prey. Unfortunately my recording gear at the time was not good enough to capture high ultrasonic signals, however I was lucky enough to capture this unique audio bio-spectrum of amazonian flooded forest; an audio bio-spectrum beautifully organized like an orchestra formed by millions of diverse creatures living in an incredible delicate harmony conducted by evolution.
The above-mentioned speculation over recorded audio and spectrogram is my mere guess based on my limited knowledge and experience about animal communication methods and biology. I would be more than happy to know about exact species and exact methods used to produce those signals. Hopefully i will receive some feedback on this. For those interested in learning about animal communication principles more in depth, below I have gathered some data about sound production methods from one of the most complete resources in the field of Biology, ‘Principles of Animal Communication’ by Jack W.Bradbury and Sandra L.Vehrencamp of Cornell Lab of Ornithology and Department of Neurobiology and Behavior Cornell University. There is link in footnotes as well.
Animal sound production methods falls in four broad categories: 1. Movement of a solid body part against another solid. a. Percussive striking: Animal strikes two solid objects together with a rapid motion. Examples such as Pileated woodpeckers (Dryocopus pileatus), Eastern diamondbacked rattlesnake (Crotalus ndnmanteus), White stork (Ciconin boycinnn) and etc. b. Stridulation: Rubbing two solids together to produce more continuous vibrations. Examples are vertebrates such as grunts(Haemulidae), arthropods such as Scorpion( Rhopalurus) and arachnids such as beetle and moth. c. Buckling: Bending of a highly elastic plate of cuticle by body muscles until the plate buckles and snaps into a different configuration producing impulsive vibrations. Examples are Bladder cicada (Cystosoma saundersii), Arctiid moth (Bertholdia trigona) and etc. 2. Movement of a body part to create surface waves at a boundary between media. Examples are some aquatic animals living on or near the surface of a body of water like Hemipteran water striders (Gerridae). 3. Movement of a body part to produce waves within a fluid medium. a. pulsation: To alternately contract and expand the surface of a closed but flexible object, so that medium is forced to move in concert with the surface. Examples are American lobsters and mantis shrimp. b. Fanning: Moving a flat solid object cyclically along a line perpendicular to its surface to produce a parallel movement of the nearby fluid medium. The wings of insects provide a classic example. Male mosquitoes (Culicidae), male Drosophila (Drosophilidae) and large fruit flies (Tephr itidae) are known to use this method. c. Fluid Compression: Rapid modification of local pressure in a fluid medium that it generates far field sounds. Example like Snapping shrimp (Alpheidae). d. streaming: When the signaler moves sufficiently rapidly through a fluid medium that the flow over its appendages generates vibrations. Examples such as Hummingbirds, woodcock (Scolopax tninor) and etc. 4. Movement of a fluid medium against a body part. There are two basic types of vibrations that might be generated: vocalizations and aerodynamic sounds. Examples are most of vocal mammals and birds.
References
↑ 1 | “Apollonius Rhodius, Argonautica, Book 2”. Archived from the original on 30 August 2017. Retrieved 15 October 2018. Amazon etymology |
↑ 2 | https://www.etymonline.com/word/amazon |
↑ 3 | Bradbury, J. W., & Vehrencamp, S. L. (2011). Principles of Animal Communication (2nd ed.). Sinauer Associates is an imprint of Oxford University Press. |
↑ 4 | von Muggenthaler, Elizabeth (2003). “Songlike vocalizations from the Sumatran Rhinoceros (Dicerorhinus sumatrensis)”. Acoustics Research Letters Online. 4 (3): 83. doi:10.1121/1.1588271. Also cited by: West Marrin: Infrasonic signals in the environment, Acoustics 2004 Conference |
11 thoughts on “The Sound of Amazon Flooded Forest”
These is amazing, I feel I am in deep forest because I knew what kind of person recorded these great sound with high quality microphones(not expensive one :D).
He also recorded my longest speaking through my life.
I love you man.
Thanks for being such an amazing friend Mori. It was simply not possible to run this blog easily without your help.
I appreciate you sharing this blog article. Really looking forward to read more. Fantastic. Juditha Bail Zulema
Thanks for reading Juditha.
Fantabulous!
Thank you for sharing this wonderful experience and serene sounds! Looking forward to hear many more of them!
Thanks for reading Sara
Houshang – that’s truly remarkable, and I learned so much from your blog! What a lucky person you are to have visited such an amazing place. Your dear sister, Sara, kindly gave me the link – so thanks to you both!
Thanks for reading Mike
I love the efforts you have put in this, thank you for all the great posts. Devina Temple Artur Annelise Werner Isleana
Very good article! We are linking to this particularly great post on our website. Keep up the good writing. Trude Clifford Stockton
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