Codex Amphibia: the Explosive Breedings

Codex Amphibia (Phonotaxis) was recorded, composed and mixed between 2016 and 2020 in French Guiana and France by Thomas Tilly. These pieces are part both of a scientific and artistic collaborative project conducted with Herpetologist Antoine Fouquet – research associate at the Centre National de la Recherche Scientifique (CNRS). These compositions follow Codex Amphibia (an Interpretation of Explosive Breeding), released in 2018 on Glistening Examples.

Texts: Antoine Fouquet & Thomas Tilly
Translation: Valérie Vivancos

The Explosive Breedings

Antoine Fouquet – Research Fellow at the CNRS.

Amphibians use a staggering amount of reproduction modes. Many species are indeed highly dedicated to caring for their offspring, sometimes through quite sophisticated parental care systems. Thus, some are viviparous and give birth to already formed offspring, others incubate their tadpoles in their stomachs or the skin of their backs. These species produce only a small number of offspring but devote a lot of energy to maximising their survival. Other amphibian species, however, have opted for a diametrically opposite strategy. They produce a large quantity of eggs that will be left to their own devices. Species that have opted for this strategy often synchronise their reproduction and aggregate massively when conditions are optimal. This is called explosive breeding.

This phenomenon can be observed in temperate environments, where it probably gave rise to the myth of “rains of toads“, but it takes on truly biblical proportions in tropical forests. In the French Guiana, the first heavy rains in December mark the end of the dry season and create temporary ponds within a few days. This is when thousands of frogs, possibly from more than a dozen different species, wait to aggregate within a few square metres for a single night of sexual frenzy. These short breeding events can bring together tens of thousands of yellow, brown, large or tiny frogs that rush around and become entangled in sound and visual chaos. For those lucky enough to have witnessed them, these explosive breeding events truly are unforgettable.

Although very spectacular, these events are, however, very difficult to study and therefore quite often misunderstood. One of the presumed advantages of this strategy is to outrun and overwhelm predators (eels, snakes, turtles, arthropods…) attracted by the sudden profusion of food. Some of these predators are actually other frogs, such as Leptodactylus knudseni and Leptodactylus mystaceus. These species systematically arrive before the others and lay their eggs on the ground of the ponds that are still dry, while protecting them from desiccation by producing a foam nest. Their tadpoles, which feed on the eggs and tadpoles of other species, are thus ready for the big night and will be able to thrive thanks to the abundance of food.  

What remains unclear, nevertheless, is how so many individuals from different species can synchronise their breeding so accurately. Some of these species are exclusively arboreal and only come down from the canopy on the occasion, while others, terrestrial and stubby, do not seem to be suited to rapid movement over long distances. These vertical and horizontal migrations involve numerous risks and are energy-consuming. However, these events are so sudden that the signal enabling amphibians to synchronise their reproduction has to be unequivocal and powerful. Weather conditions and the memory of the location of ponds are, of course, part of the equation, but other signals such as acoustic ones are also likely to be used. The sound sequence of an explosion follows a very precise sequence, with the regular “WOOPs” of the Leptodactylus and the “POCKs” of the Callimedusa, which may announce, if not the right moment, at least the precise location of the gathering. On the other hand, the screeching song of the tiny Chiasmocleis or the low-pitched squeaks of the Trachycephalus could be part of the triggering signal.

The peak of the breeding activity offers a visual spectacle but also generates a sound wall of around 100 decibels. The entire sound spectrum thus generated can be heard by humans up to several hundred metres from the pond, so much so that studying the phenomenon requires hearing protection. How the different species there can find their potential partners in such a cacophony remains a mystery, considering the distinction between the different phonemes is extremely tricky for the human ear. 

After a few hours of explosive breeding, the pond is coated with a massive layer of eggs and becomes fairly quiet again. A few species with prolonged reproduction then take over to occupy the sound space but the fate of these populations is mainly at stake within the water; in barely 24 hours these eggs will etch into millions of tadpoles which, in turn, will exploit different ecological niches. The biology of these tadpoles and the doubtless complex interactions (especially the acoustic ones) that they maintain, also remains largely unexplored. In the end, a true symphony is being performed, with its prelude and its various movements. Such an event creates the perfect conditions for an encounter between a herpetologist and a sound artist.

In 2016 and 2018, Thomas and I set up camps near these ponds to observe and listen to the behaviour of the different species before the explosion. One of the things I had been eager to test for several years was if the sound recordings of certain species of frogs could encourage other species to gather on the pond. In 2016, a loudspeaker playing an hour-long recording of explosive breeding (all species) was first set up near a pond. Another pond was left without sound emission, which made it possible to compare the behaviour induced by playing sound. The difference was very clear since several dozen Osteocephalus leprieuri and other species were observed on or near the speaker after only a few minutes. In 2018, we decided to develop the experiment with a series of devices, this time set up on three ponds, each equipped with four sound emitting stations. Each of these stations had a speaker playing a distinct acoustic stimulus (recordings of Trachycephalus, Chiasmocleis, calibrated electronic noise, or absence of acoustic stimulus). For 7 nights, we played these signals and monitored the number of individuals of each species attracted by a particular acoustic stimulus.

The results and details of this experiment are reported in the attached article:

Simulated chorus attracts conspecific and heterospecific Amazonian explosive breeding frogs

Phonotaxis…

Thomas Tilly, artist

Phonotaxis (uncountable) Noun: (physiology) The ability to move in an orientation with respect to a source of sound.

By questioning phonotaxis between species in explosive breeding in the Amazon, i.e. the existence or absence of interspecific relationships, in sound, we necessarily undertake to question how we, humans, perceive an environment. The abrupt change in dynamics induced by the phenomenon is also ours, and we find ourselves physically and mentally included in a process that escapes us. We are disturbed, attracted, fascinated, but we have no real grasp nor control of the moment, of its stakes, of the strategies it deploys. We listen, observe, record, film, without being able to go beyond the stage of interpretation.

These events unsettle us cognitively but also culturally in that they shatter images linked to a context. They are neither the expression of an equilibrium nor of a supposedly hostile nature. On the contrary, they feature an imbalance, a brutal and sudden disruption of the order of things whose only purpose is the continuity of the living. They are making sense to the animal world just like the irrationality of a concert of noise music or an overflowing crowd does to the human world. It is no longer about sharing but about saturating space, an exaggeration of the spectra of light and sound. This overrunning of dynamics may only make sense in its very short-lived nature; an extreme brevity that transforms localised spaces such as ponds into autonomously functioning areas, distinguishing itself from the forest network to later reintegrate it better by feeding it with new beings. The breeding begins its pre-explosion phase in some heterogeneity with the place. It then asserts this overrunning in the explosion and post-explosion phases, and finally reconnects with the surrounding area. The animals then disperse and the hundred acoustic decibels of the explosion give way once again to a forest whose audible spectrum seems to be precisely distributed.

Explosive breeding events hold their power over this environment, these surroundings, imposing themselves onto bodies and tree trunks; moving away or attracting other species and even able to neutralise some of them (a herpetologist friend of mine told me that after a few hours on an explosive pond the effects of the sound made her vomit). The species taking part in these gatherings seem to prefer the univocity of a saturated sound spectrum than their own phonemes. It is no longer single “voices” that are emitted and received, but their accumulation into a wall of noise. Once again, the interpretation of a datum only opens up questions about what we understand of the situation and the ontological prisms through which we perceive it.

The experience of explosive events induced in me the paradoxical feeling of being an intruder at the right place, the listener/spectator of a ritual intimately resonating with my stubbornness in seeking a confrontation with this kind of environment. The principle of phonotaxis observed in these animals is natural, while my attraction to and towards this noise is cultural. However, we have no more control over the mechanisms that activate animal phonotaxis than we do over those that push us to flee or immerse ourselves in a pool of high frequencies. Fascination with these sounds alone, as well as the only analogy with the musical aesthetics that have led to this, are not (or no longer) enough, in my opinion, to explain the ambiguous relationship we keep with this context. We are unsettled by what is not us but seems to function along similar modalities.

While the first part of this work – Codex Amphibia (an interpretation of the explosive breeding phenomenon – Glistening examples 2018) – raised the question of the interpretation of non-human languages, Codex Amphibia (Phonotaxis) deals with the peak of the explosion as a reference point for an environment. The recordings and compositions resulting from this fieldwork explore the core of the phenomenon and the porosity towards its surroundings, which are made of other dynamics, other timbres of human and non-human origins. These pieces have been produced through our field observations and, in parallel, with a research work conducted by Antoine Fouquet and myself with the help of a team of volunteers, later detailed by Antoine and several collaborators in the article “HETEROSPECIFIC CHORUS ATTRACTION IN TROPICAL FROGS”. Through the meeting of both our scientific and artistic approaches; a hybrid method that pushes our questioning and paradoxes further, we hope to expand the possibilities of a different relationship with this forest.

The results and details of this experiment are reported in the attached article: Simulated chorus attracts conspecific and heterospecific Amazonian explosive breeding frogs

Codex Amphibia (Phonotaxis)

This work received the “Investissement d’Avenir” grant from the Agence Nationale de la Recherche (CEBA, ref. ANR-10-LABX-25-01)”, the « Brouillon d’un rêve, Pierre Schaeffer » grant from the Société Civile des Auteurs Multimédia (SCAM) and was supported by Le Lieu Multiple, Jazz à Poitiers, Césaré and Studio d’en Haut.

Thomas Tilly and Antoine Fouquet thank to:

The Réserve Naturelle des Marais de Kaw Roura, the DEAL (Direction de l’Environnement, de l’Aménagement et du Logement), the LEEISA (Laboratoire Ecologie, Evolution, Interactions des Systèmes Amazoniens USR3456), Anthony Taillard, Michel Blanc, Mathias Fernandez, Timothée Lepape, Laboratoire IRD LAMA Cayenne, Association GEPOG (Groupe d’Etude et de Protection des Oiseaux de Guyane), the CERATO herpetological society, Pierre Judon, Jason Lescallet, Gildas Houdebine and Agathe Coutel; for their technical support.

and:

Bettina Lê, Sevahnee Pyneeandy, Hugo Reizine, Anaïs Bonnefond, Benoit Villette, Timothée Lepape, Mathilde Segers, Laetitia Proux, Audric Broux, Vincent Premel, Élodie Courtois, Philippe Gaucher, Lois Boucher, Yanick Lima, Vincent Rufray, Mael Dewynter, Elven Remerand, Martin Bonhomme, Amélie Beillard Alexandra Le Manchec, Morgane Sineau, Florie Delfour, Joris Grenon,