We organized this second introductory workshop on orthopteran bioacoustics, taught in Spanish, continuing our efforts to grow the community of interested Spanish speakers. This time, we visited the Cuenca mountain range. We enjoyed pleasant temperatures and the presence of Iberian endemic species, perfect conditions for the successful TEOSS 3 Workshop.

We were a good group of 15 people from all over Spain (Madrid, the Balearic Islands, Galicia, Cuenca, Zamora, Toledo, Huesca, etc.), missing our Portuguese colleagues, whom we’re sure to meet up with at a reunion soon. We followed a training program, dedicating a lot of time to the field, acquiring a minimum level of knowledge, and concluding the workshop with the recordings identified and uploaded to the Xeno Canto server. It was a pleasure to meet with such a motivated and hardworking group. Alternating fieldwork, theory, and sampling is undoubtedly the best pedagogy for learning about ecology and species; it’s known as Learn by Doing. We believe that the positive atmosphere and group dynamics motivate amateur biologists to participate in citizen science projects.

Day 1. Reception

Afternoon reception at the El Cerviñuelo rural hostel, near Las Majadas (Cuenca province). This former forester’s lodge is quite imposing and comfortably accommodates groups seeking tranquility and a well-preserved Mediterranean forest at an altitude of 1,400 meters. In addition to our sheep and cow neighbors, we immediately enjoyed the wildlife, including a very vocal midwife toad (Alytes obstreticans) and the ocellated lizards that inhabit the nearby rocks.

Our first nighttime outing allows us to visually inspect the surroundings and detect the most abundant orthopterans, which we will study in the following days. The nighttime atmosphere is rich with the soft cooing of the European nightjar (Caprimulgus caprimulgus), the subtle barking of common frogs (Pelophylax perezi), and the melodious song of the crickets Oecanthus pellucens, so typical of our summer nights. The star species was Albarracinia zapateri, which we were able to observe at leisure. This large insect with bulging eyes draws attention due to its intense green body color, which contrasts with its straw-colored tegmina.

Day 2. Los Cuchareros / Fuente de la Tía Perra

10:00-11:00. An introduction to the TEOSS project, its objectives, and methodology. We highlight the importance of the Iberian Peninsula in the European context and the need to expand basic knowledge about many of its species. Microphones will be distributed to attendees.

11:00-15:00. We take our first steps, equipped and ready to record the stridulations of the orthopterans we encounter along the way. We explore the area around the Tía Perra spring, with a stream of water where odonates and the magnificent Chorthippus jucundus abound. The grasshopper density was quite moderate, although the grasses were not yet dry in the higher reaches of the mountain range. Cicadas abound among the pines and saturate the sound environment, although they allow us to make some recordings.

6:00-9:00 PM. We begin the afternoon with a spectacular video of A. zapateri copulation recorded the night before. The Ephippigerinae are notable for their peculiar biology: the males of this group mate by passing through a large whitish structure that preserves sperm. The female then separates from the male, carrying this «spermatophore,» which she may carry attached to her body for hours, as fertilization takes a long time. Most surprisingly, the female feeds on the spermatophore, which turns out to be little more than a nuptial gift, facilitating the maturation of the eggs, which requires a great deal of energy.

This will be followed by talks on the biology and acoustics of orthopterans; the use of the Observation.org platform to collect field data; and the data collection sheet that helps organize sampling concepts.

10:00 PM – 3:00 AM. We explore the surroundings of the forest lodge again until late at night. Orthoptera are abundant, and we record Oecanthus, Albacarrinia, Eugryllodes, Platycleis, Thyreonotus, Tettigonia… After familiarizing ourselves with the use of recording equipment during the day, we can concentrate on approach and recording techniques.

Day 3. Los Altos de Las Majadas

We changed our surroundings and spent the morning sampling the low scrub and sparse terrain around the Las Majadas campsite. The habitats were completely different, as was the insect community. We also discovered new species of Orthoptera: Lluciapmaresius, Chorthippus, Omocestus minutissimus, and several others.

6:00 PM – 9:00 PM. Back at the hostel, we continue with talks on Orthoptera. Olga Fernández and Callista Sivori present their ongoing work on developing databases for TEOSS and on the distribution of crickets in Spain. We review several case studies (Gryllus, Oecanthus) and the application of bioacoustic techniques to understand Orthoptera. José Ramón Correas then reviews the species sighted during the day, with photos taken in the field, and explains essential morphological elements for identifying grasshoppers. We conclude the theoretical section with a demonstration of echometers, ultrasound recorders that can be attached directly to a mobile phone.

10:30 PM – 1:30 AM. We switched to using ultrasound detectors to explore the forest. They revealed the richness of ultrasonic patterns of the Ensifera, obviously beyond our hearing range. The Ephippigerida aerolaria stands out, having been very discreet until now. The placement of a light trap allowed us to see a large number of moths, although no orthopterans came to the light.

Day 4. Laguna de Uña

The last day begins. It takes us to Uña Lagoon, where we search for new species. A meadow allows us to review the Chorthippus, although the wind and the inherent difficulty of recording in these environments make it clear that recording Acrididae songs requires a lot of patience and dedication.

The perilagoon belt disappointed us with the lack of hygrophilous species at the time of our visit, although we were rewarded by the detection of the rare cricket of the genus Petaloptila.

After the picnic and a deliciously fresh watermelon, we headed to a restaurant to set up our unique Internet Café. The lab session begins, which will take us until 7:00 PM. We’ll be processing all the data collected so far: synchronizing the observation data from the app to the Observation.org user account; downloading and renaming the sound files; importing the data into Audacity to process the files; and finally, uploading this information and files to the Xeno Canto platform.

Day 5. Farewell

With homework done, the end of the workshop offers a time for discussion and the exchange of diverse experiences… These conversations take us on a journey through the American jungles, the Galician rivers and their rampage, the Iberian moors and their extreme temperatures… and many more topics: everyone contributes. Finally, we bid farewell and promise to see each other again in the near future.

_

This project has received funding from the European Union’s Horizon Europe Research and Innovation programme within the framework of the TETTRIs Project funded under Grant Agreement Nr 101081903.

Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or REA. Neither the European Union nor REA can be held responsible for them.

Baudewijn Odé is a prominent Dutch researcher specializing in the bioacoustics of grasshoppers. His work focuses on the study and analysis of sounds produced by crickets, grasshoppers, and bush-crickets, significantly contributing to the field of acoustic entomology.

As a member of the IUCN Grasshopper specialist group, Odé has played a crucial role in developing and implementing methodologies for recording and analyzing orthoptera sounds and sharing sound recordings to facilitate field research to grasshoppers in Europe. His participation in the TEOSS (Training for the European Orthoptera Sound System) project has been fundamental in establishing standardized protocols for acoustic data collection across Europe.

Odé has led international workshops, such as the one held in Sierra de La Demanda, Spain, where he shared his expertise in field recording techniques and laboratory analysis. His focus on creating and expanding the Xeno-canto database to include orthopteran sounds demonstrates his commitment to accessibility and the sharing of scientific knowledge.

In addition to his technical work, Odé has contributed to developing innovative tools for studying bioacoustics, collaborating on specialized software like RThoptera. His experience spans from data collection in the field to detailed analysis of oscillograms and participation in scientific publications, making him a key figure at the intersection of technology and orthopteran biology and conservation.

Introduction to bioacoustics

How did you first become interested in the bioacoustics of Orthoptera?

Being a descendant in a musical family, I have always been interested in nature’s song. In 1990 I was struck by the fact that nobody knew Grasshopper songs. As soon as I saw the vivid communication between individual grasshoppers, I fell for diving into their acoustic and behavioural world.

What is the importance of bioacoustics in the study and conservation of these insects?

First of all, for many species listening is the major technique to identify species and discover their presence or abundance. Conservation always starts with knowing where a species resides, assessing their rarity and maybe population trend. Bioacoustics for many species are really helpful in this respect. However, secondly, I would argue that making sound communication aspects of these small animals available to a wider audience will greatly enhance the social support for this group, literally giving them a voice.

Methodology and techniques

Could you describe the workflow you use to collect and analyze Orthoptera sounds?

I apply different techniques in collecting sounds. I am both actively hunting in the field for singing specimens, but I also use passive acoustic monitoring, putting a recorder in the field for some time. Finally, to be able to produce high quality sound recordings of well-identified specimens, I record them in a small studio. All my recordings end up in a big database (using Soundminer software) with as much as possible metadata. Analysing sound recordings for me is for a large part listening, frequently listening at slow playback speeds (and not just for ultrasonic songs). When it comes to describing the characters of a song, I use software like Steinberg Wavelab and Audacity, making it possible to measure temporal and spectral characteristics. Recently, the free Rthoptera R-package has been added to my analysis tools.

What types of microphones and equipment do you recommend for fieldwork?

This really depends on your goal. If you are keen to record single specimens it really helps if you have a directional microphone (or parabolic microphone), or a microphone on some kind of rod (technically called boom pole) to be able to reach close to the singing animal, to be able to get rid of most of the surrounding noises. Being able to listen through headphones to be able to pinpoint the microphone before recording may help to record hidden grasshoppers.
On the other hand, you may want to record a chorus of different species, maybe as a part of a monitoring research, showing species diversity or seasonal or yearly changes. Then longer recordings (soundscapes) are useful. In these cases, you would want to have an omnidirectional microphone and depending on the deployment time, a long battery life of the recorder. Specialised recorders are available for these purposes, like Audiomoth and Batlogger.
In both cases standard recording quality (CD quality, 44.1 kHz) may be sufficient. However, many species produce mainly or partly ultrasonic songs. It may be advised then to use a recorder with a high sampling rate (e.g. 96 kHz) and microphones with a representation of ultrasonic frequencies. Especially ultrasonic microphones or recorders, used for bat monitoring, are suitable in such cases.

Projects and collaborations

Tell us about your participation in the TEOSS (Training for the European Orthoptera Sound System) project.

Participating in TEOSS really makes me happy, as I can help participants to study Grasshopper sounds and make them add to freely available sound recordings. Also, I am very happy to see that the study and conservation of Grasshoppers in general has a future with more people interested and involved..

How has your experience been collaborating with other researchers in international workshops?

I really enjoy international workshops, both to disseminate my knowledge and experience, but especially also to learn about  other perspectives, knowlegde and needs of other researchers.

Challenges and advancements

What are the main challenges in recording and analyzing Orthoptera sounds?

For starting recordists I suppose species identification and analysis is a major issue. Although many sound recordings are freely available or their songs are described in publications, I tend to get a lot of questions on identification of sounds.
In the field, it is very difficult to both record a specimen and identify the specimen by its morphology, let alone to analyse and describe their songs. I really hope that in the near future with machine learning tools many people will be able to identify most European species. Yet, we do have a vast job to record and describe the songs of about 250 European species of which no sound recordings are available in public databases.
For me personally, sound recording and analysing is a free time activity, and my free time is always limited.

What recent advances in technology or software have improved your work?

Sound recording gear is still improving and has become affordable for many more people. For me, working with ultrasonic microphones and recorders is helping me a lot to not just focus on temporal but also on spectral characters of Grasshopper songs. In terms of analysing, I am a student learning to use R tools like Rthoptera to analyse sound recordings, but the potential of these tools is vast.

Xeno-Canto database

How does the Xeno-Canto database contribute to the study of Orthoptera bioacoustics?

Being largely open source, anyone studying Grasshopper songs can freely get to know anduse a lot of sound recordings of this group. Most sound recordings are georeferenced and contain a lot of relevant metadata, being valuable extra information for research.

What goals do you have to improve this database in the future?

Apart from achieving better species coverage in Europe and worldwide, I think adding automatic species recognition and song annotation would help to validate and improve the quality of the database. Also, this would facilitate analysing soundscapes for all singing species.

Conservation and biodiversity

How does bioacoustics contribute to the conservation of Orthoptera and biodiversity in general?

see question 1b.

What role does citizen science play in your research?

My own research may be regarded as citizen science, being conducted as a hobby. Being able to have a larger collection of sound recordings and observations, based upon citizens sharing their well-recorded and well-identified recording, helps me a lot with my own research.

Future of research

What are your future objectives in the field of Orthoptera bioacoustics?

I will certainly participate in recording European grasshoppers with no or little representation in the database of Xeno-canto.
As soon as new machine learning tools become available, I suppose I will participate in validating the quality of those tool.
At present, I am involved in research in the taxonomy of Italian wartbiter species, with sound recording analyses as my role.
I hope at some stage it will be technically easy to combine sound recording with leg or wing movement to better understand the mechanics of sound production.

What advice would you give to young researchers interested in this field?

Listen (and look) carefully to grasshoppers singing. You may discover new songs, new species or new behaviour. Furthermore, it would be great if young researchers would be involved in developing identification and analysis tools, not just to identify single species recordings, but also being able to identify all species in a soundscape. This latter technique would be very important to facilitate monitoring biodiversity in grasshopper communities.

Personal experiences

Could you share an interesting anecdote from your fieldwork

Long ago, I encountered a singing male of a field grasshopper, with an answering female. This is a rarely encountered event, but what stroke me especially, was the fact that I could feel the excitement of both animals, just before mating. Hence, I tend to see a parallel with human excitement in these small insects.

What has been your most exciting or surprising discovery in your career?

I suppose most surprising for me was discovering the song of Natula averni, Reed cricket. This is a very small and extremely difficult to find cricket. Until 2006 it was only known from one location in Italy. With two friends and hard labour we were able to find one in Turkey. After this discovery, we and several other orthopterists were able to find it throughout the Mediterranean area.