Backed by the Tour du Valat until 2027, the Rest-Chir’Eau project is based on an innovative approach that studies bat activity to assess the ecological functionality[1] of wetlands while guiding their restoration. By combining field monitoring, citizen science, and awareness-raising activities, Rest-Chir’Eau aims to increase the still limited knowledge on this subject, while encouraging the involvement of local stakeholders.
This project will contribute to global expertise on the management and restoration of wetlands, while promoting the conservation of threatened species including bats. The data collected will be used to draw up a local restoration plan for the former Bras de Fer branch of the River Rhone in the Camargue.
Are bats barometers of the ecological status of wetlands?
Knowledge of bats and their interactions with natural environments is still limited, probably because of the beliefs regarding this nocturnal animal and the difficulties involved in observing and studying them. Chiropterology, the science dedicated to the study of bats, is also relatively recent, and has seen significant advances in recent decades with the development of audio capture technologies such as ultrasonic detectors.
Although 75% of the chiropterologists questioned acknowledge a close link between wetlands and bats, there is little tangible evidence to support this position. In addition, several scientific studies suggest that wetlands could prove to be excellent bio-indicators in the context of global changes (climate change, landscape development, land use).
This is the background of the Rest-Chir’Eau project, led by the Tour du Valat and winner of the Rhone-Mediterranean and Corsica Water Agency’s 2023 “Water and Biodiversity” call for projects. It is based on an innovative approach: studying bat activity to assess the ecological functionality of wetlands and guide their restoration. This project will involve analysing the interactions between species and their environment in terms of their requirements, such as their need for ecological continuity and a mosaic of habitats.
Locally, the aim will be to define priorities in terms of restoring and sustainably managing the turquoise infrastructure[1] near the former Bras de Fer branch of the River Rhone, now crossed by the Japan Canal, which is major irrigation infrastructure in the Camargue.
Data collection organised at several sites in the Camargue
The first two years of Rest-Chir’Eau have been marked by intense activity in the field to define a restoration plan for the turquoise infrastructure. In 2024, several monitoring campaigns were carried out at seven sites, including private properties in partnership with their owners, as well as a restored marsh located on the Petit Badon Estate. This site will be monitored continuously from 2024 to 2026. This inter-annual data will provide a better understanding of changes in bat activity in response to environmental variations, as well as shedding valuable light on the dynamics of a restored ecosystem.
Night listening of bats To represent the diversity of habitats found in Mediterranean marshes (hydrophytic water bodies, reedbeds, sansouïres), several listening points were selected on the different sites studied. Sophisticated recording systems were installed at these locations: boxes fitted with microphones, programmed to activate 30 minutes before sunset and stop 30 minutes after sunrise. These devices capture the high sound frequencies of bats (10 to 150 kHz), but also other sounds, such as those of insects. Vegetation, insect populations and hydrological and meteorological variables were also monitored at each point. It was very challenging to apply this rigorous and innovative experimental protocol: We had to install the equipment in sometimes extreme conditions – on the water, in the middle of dense reedbeds over 2 metres high, or on isolated sites with no access roads. The team had to be ingenious and flexible to overcome these obstacles while adapting to the presence of livestock and the vagaries of the elements. Another challenge, but also a real added value, lay in the multiple monitoring sessions carried out throughout the year. This approach makes it possible to capture bat activity at different stages of their phenological cycle[3], while observing the environmental variations specific to the marshes. The study of these Mediterranean habitats has proved particularly relevant, as their seasonal nature, the gradients in vegetation, and the diversity of species they host can influence the presence of certain bats and their type of activity. Acoustic analysis, a precise and essential taskOnce the recordings have been collected, a meticulous analysis phase begins. The ultrasounds emitted by bats, inaudible to the human ear, require complex computer processing. The files first go through pre-analysis software that uses artificial intelligence to identify species according to the characteristics of the sound waves. But these systems are not infallible: Each result must be checked manually to avoid errors. “A single night of recording can require between 3 and 12 days of processing time, depending on the complexity of the analysis. To give you an idea, one night can contain between 200 and 3,000 soundtracks. In 2024, we recorded 168 nights, which represents over 250,000 files to process! – Pauline Rocarpin, REST-CHIR’EAU project manager But it would take more than that to discourage the Rest-Chir’Eau team! These recordings provide a wealth of information: In particular, the shape of the waves can be used to determine whether a bat is feeding or moving around, and thus provide a better understanding of the ecological dynamics of each site. |
Citizen science, an asset for improving data collection and ensuring that local stakeholders get significantly involved in the project
One of the Tour du Valat’s ambitions for the Rest-Chir’Eau project is to encourage local players to become significantly involved in the project and the issues at stake in the area, by enabling them to play an active part in the actions carried out, such as data collection.
In 2024, volunteers – from the general public, partners, and local players – were mobilised to help the team install and retrieve the monitoring equipment. In 2025, observation sessions will be organised, and a participatory monitoring protocol launched, via an online survey open to residents of the Camargue. Everyone will be able to pass on their observations to add to our knowledge of bat activity and identify key sites near the former Bras de Fer branch of the River Rhone that it will be important to preserve, such as those where there are bat roosts, and the ecological corridors that allow them to move around.
Several local partners have already joined the venture to help bring the project to life and raise the awareness of as many people as possible. This includes the Camargue RNP, which is organising International Bat Night at the Tour du Valat this summer, and the CPIE-Rhône-Pays d’Arles (environmental initiatives centre), which is planning activities for schoolchildren.
By actively involving local citizens and stakeholders, Rest-Chir’Eau aims to forge strong links with local stakeholders and raise awareness of a wide audience on the importance of preserving wetlands, two crucial activities for ensuring the long-term preservation of these ecosystems.
WOULD YOU LIKE TO GET INVOLVED?
- You can contribute to the participatory bat monitoring survey in the Camargue by following this link
- Subscribe to the Rest-Chir’Eau project newsletter to receive the next participatory monitoring dates.
- Meet the Rest-Chir’Eau project team on Sunday 2 February 2025, at the Tour du Valat Open Days (full programme will be published on our website).
GLOSSAIRE
[1] Ecological functionality : the capacity of an ecosystem to ensure biological cycles (reproduction, rest, food, movement) and to provide ecological services (pollination, natural water purification, food source).
[2] A key concept developed by the Agence de l’Eau, the Turquoise infrastructure refers to all the environments land and water in a given area, which enable many species to complete their life cycle.
[3] Phenological cycle : groups together the developmental stages of a living organism, influenced by the seasons and environmental conditions, and is a valuable indicator for understanding the interactions between organisms and their environment.
Bibliographie
[i] Mas M, Flaquer C, Rebelo H, López‐Baucells A (2021) Bats and wetlands: synthesising gaps in current knowledge and future opportunities for conservation. Mam Rev 51:369–384. https://doi.org/10.1111/mam.12243
[ii] Jones G, Jacobs DS, Kunz TH, et al (2009) Carpe noctem: the importance of bats as bioindicators. Endangered Species Research 8:93–115. https://doi.org/10.3354/esr00182
Russo D, Salinas-Ramos VB, Cistrone L, et al (2021) Do We Need to Use Bats as Bioindicators? Biology 10:693. https://doi.org/10.3390/biology10080693
Tuneu-Corral C, Puig-Montserrat X, Flaquer C, et al (2020) Ecological indices in long-term acoustic bat surveys for assessing and monitoring bats’ responses to climatic and land-cover changes. Ecological Indicators 110:105849. https://doi.org/10.1016/j.ecolind.2019.105849
Contact
Pauline Rocarpin, Project manager, Tour du Valat
Financial partners
Technical partners
