Why do elephants use seismic communication?

值得注意的是，大象沟通的一种方法是通过地面或地震振动。我们知道，大象会产生并应对小型地震，利用被称为“隆隆声”的发声在彼此之间传递信息，同时产生声学振动。然而，这些神秘的地震信号在自然环境中的生物作用缺乏证据。调查它们的生物作用对于了解濒危大象如何受到土地利用变化的影响非常重要，包括由于基础设施开发而增加的人为地震噪音。对于地震震动对大象的生物学作用，我们有两个假设。首先，地震信号可以实现公里级的远距离通信，这超出了空气传播的声音、气味或视觉所能提供的范围。对这一点的支持是基于理论和轶事证据，例如理论上的振动与空气体积相比通过地面传播得更远。其次，地震振动可以作为声学信号的“备份”，以促进在任何空间尺度上的可变环境中的信息传输。这得到了动物交流理论和建模工作的支持，这些工作表明地震和声学成分受到风或地质等不同环境因素的影响。为了解决这个难题，我们将窃听大象隆隆声产生的地震和声学信号。这使我们能够了解振动信号的信息内容在传播过程中如何变化，特别是地质，噪音，风向等环境因素的不同影响，并与理论进行比较。我们的第二种方法将测试大象如何对地震振动做出反应，无论是大象自己产生的还是通过回放实验，让我们能够操纵信息内容。通过操纵声振动和地震振动的位置和噪声含量，我们可以在近距离内检验这两种振动类型的信息和噪声的相对重要性，这将为检验我们的两个假设提供证据。特别是，地震振动是否对大象通信具有生物学作用，取决于传播距离和/或环境因素。如果两者都不是，这支持地震和声振动形成一种通信模式，这对于理解振动通信系统的演变很重要。我们的目标是了解为什么大象使用地震振动进行交流。除了其功能的重要性，了解大象使用地震信号的目的将为自然和圈养环境中大象的保护和管理决策提供信息，包括人为噪音对大象造成的挑战。通过这项研究，我们还将开发新的方法，通过窃听大象隆隆声的声学成分来实时远程监测大象，这可以帮助大象在未来的保护。

Remarkably, one method through which elephants communicate is via ground-based, or seismic vibrations. We know that elephants generate, and respond to, mini-earthquakes to transfer information between each other using vocalisations known as 'rumbles' that concurrently generate an acoustic vibration. Yet evidence for the biological role of these enigmatic seismic signals in the natural environment is lacking. Investigating their biological role is important for understanding how endangered elephants might be affected by changes in land-use, including increasing anthropogenic seismic noise due to infrastructure development. We have two hypotheses for the biological roles of seismic vibrations for elephants. Firstly, seismic signals could enable long-distance communication at the kilometre scale, beyond what air-borne sound, smell or sight could offer. Support for this is based on theory and anecdotal evidence, for example vibrations in theory propagate further through the surface of the ground compared to the volume of air. Secondly, seismic vibrations could act as a 'back-up' for acoustic signals to promote transfer of information over variable environments at any spatial scale. This is supported by animal communication theory and modelling work, which show that seismic and acoustic components are influenced by different environmental factors such as wind or geology. To solve this puzzle, we will eavesdrop on the seismic and acoustic signals generated by elephant rumbles. This allows us to understand how information content of vibrational signals changes during propagation, specifically the different influences of environmental factors such as geology, noise, wind direction, and compare to theory. Our second approach will test how elephants respond to seismic vibrations, both when generated by the elephants themselves and via playback experiments that allow us to manipulate the information content. By manipulating the position and noise content of acoustic and seismic vibrations, we can test for the relative importance of information and noise of these two vibration types at close range.Combined, this will provide evidence to test our two hypotheses. Specially, whether seismic vibrations have biological roles for elephant communication that are dependent on propagation distance and/or environmental factors. If neither is the case, this supports that seismic and acoustic vibrations form one communication mode, which is important for understanding the evolution of vibration communication systems. Our goal is to understand why elephants use seismic vibrations for communication. In addition to its functional importance, understanding what elephants use seismic signals for will inform decisions about elephant conservation and management in natural and captive contexts, including the challenges imposed on elephants by anthropogenic noise. Through this study, we will also develop novel methods to monitor elephants remotely in real-time by eavesdropping on the acoustic component of their rumble vocalisations, which can aid elephant conservation in the future.