Periodic Reporting for period 1 - EchoBug (Echo-acoustic signalling of aposematic and cryptic insects – A bat-inspired approach)
Période du rapport: 2022-09-01 au 2024-08-31
In the arms race between prey and predators, diverse anti-predator defence mechanisms evolved. To avoid predation, many insects developed camouflage (crypsis) or chemicals that render them distasteful or toxic. To warn potential predators of their unsavoury nature, many insects evolved striking warning colours or patterns (aposematism). Insects comprise most of the diet of bats. Some of these nocturnal predators glean resting, silent, motionless diurnal insects from the vegetation. Instead of using vision during foraging, they produce ultrasonic calls and detect their prey through echolocation. In my project I wanted to investigate whether insects that make use of visual camouflage or visual warning signals also have acoustic reflection properties that allow them to hide from or signal their unpalatability to echolocating bats.
In EchoBug I studied fundamental, sensory ecological and behavioural questions about insect signalling mechanisms in different sensory modalities and the differentiation of these by echolocating bats. This project aimed to understand underlying acoustic mechanisms of predator-prey interactions and inform and inspire biomimetic methods and applications for object detection and identification. The study of echolocation is of particular interest as it forces us humans that have vision as our primary sensory modality to think about how other agents/organisms that rely upon different sensory modalities can interact intelligently with their environment. Specifically, an improved understanding of how bats use echolocation and sound in general to create a rich world model supporting a broad range of intelligent behaviours provides essential guidance for the inclusion of spatial sound cues in mobility training programs for the visually impaired.
To investigate the acoustic reflections of different signalling butterflies and moths, I used the most sophisticated bio-inspired sensor system currently available to acquire echo-acoustic sonar recordings, so called echo-fingerprints, of various species. For further comparisons state-of-the-art machine learning and signal processing techniques were applied to this extensive echo-fingerprint data set. In addition, different behavioural prey-detection and -capture experiments using live bats of the species Micronycteris microtis were conducted to explore the prevailing acoustic predator-prey interactions.
The EchoBug project successfully developed a recording system that includes two high-speed cameras synchronized with a newly designed ultrasonic multi-microphone array (NI-MUMM Array. Further it created extensive data sets of lepidopteran echo-fingerprints as well as of various bat behaviours, which are currently analysed and prepared for publication. Overall, the unique combination of lab-based measurements with behavioural test allows an in-depth investigation of the underlying acoustic mechanisms of the interaction between prey and predators.
In EchoBug I studied fundamental, sensory ecological and behavioural questions about insect signalling mechanisms in different sensory modalities and the differentiation of these by echolocating bats. This project aimed to understand underlying acoustic mechanisms of predator-prey interactions and inform and inspire biomimetic methods and applications for object detection and identification. The study of echolocation is of particular interest as it forces us humans that have vision as our primary sensory modality to think about how other agents/organisms that rely upon different sensory modalities can interact intelligently with their environment. Specifically, an improved understanding of how bats use echolocation and sound in general to create a rich world model supporting a broad range of intelligent behaviours provides essential guidance for the inclusion of spatial sound cues in mobility training programs for the visually impaired.
To investigate the acoustic reflections of different signalling butterflies and moths, I used the most sophisticated bio-inspired sensor system currently available to acquire echo-acoustic sonar recordings, so called echo-fingerprints, of various species. For further comparisons state-of-the-art machine learning and signal processing techniques were applied to this extensive echo-fingerprint data set. In addition, different behavioural prey-detection and -capture experiments using live bats of the species Micronycteris microtis were conducted to explore the prevailing acoustic predator-prey interactions.
The EchoBug project successfully developed a recording system that includes two high-speed cameras synchronized with a newly designed ultrasonic multi-microphone array (NI-MUMM Array. Further it created extensive data sets of lepidopteran echo-fingerprints as well as of various bat behaviours, which are currently analysed and prepared for publication. Overall, the unique combination of lab-based measurements with behavioural test allows an in-depth investigation of the underlying acoustic mechanisms of the interaction between prey and predators.
To test whether moths have more cryptic acoustic reflections than butterflies and whether visually aposematic butterflies also provide an echo-acoustic signal of their unpalatability, I obtained standardized echo measurements of various moths and butterflies during an added secondment at the BASElab of Prof. Marc Holderied, University of Bristol. There I was able to use advanced technology to collect high-resolution echo data of several Lepidoptera species. The data is currently being analysed for publication in an international journal and an online insect echo-fingerprint library.
In behavioural experiments with bats at the Smithsonian Tropical Research Institute, Panamá, I tested whether bats can detect and discriminate between different cryptic and aposematic prey types using their echolocation system. For the experiments a high-speed camera synchronized with an ultrasonic 30-microphone array (NiMUMM-Array) recording system was successfully designed, build and used to capture the 3D-flight paths and echolocation behaviour of the bats.
A large dataset was generated, and machine learning techniques and signal processing methods are used to automatically extract the bats' flight paths and echolocation calls from the video and audio data. This data is currently being analysed and will be used for a publication.
Throughout the project I participated in several public events and scientific workshops to present this work.
In behavioural experiments with bats at the Smithsonian Tropical Research Institute, Panamá, I tested whether bats can detect and discriminate between different cryptic and aposematic prey types using their echolocation system. For the experiments a high-speed camera synchronized with an ultrasonic 30-microphone array (NiMUMM-Array) recording system was successfully designed, build and used to capture the 3D-flight paths and echolocation behaviour of the bats.
A large dataset was generated, and machine learning techniques and signal processing methods are used to automatically extract the bats' flight paths and echolocation calls from the video and audio data. This data is currently being analysed and will be used for a publication.
Throughout the project I participated in several public events and scientific workshops to present this work.
The aim of this project was to lead to a synergism between the research fields of biology and engineering in the study of animal interactions and bio-inspired robotics. By combining sensory ecology and animal behaviour with applied engineering, signal processing, bio-inspired sensor systems, and neural networks, we can advance the development of new technologies in the field of acoustic sensors and deepen our understanding of predator-prey relationship from both sides of this interaction. By an on-going analysis of the bats’ foraging strategies, acoustically and behaviourally, on one hand, and different predator avoiding strategies in an understudied sensory system, I am continuing to shed light on the acoustic sensory world.