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Hippolyte Pouchelle
Ingénieur écologue, Egis
Published on October 19, 2018

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Egis flies to the rescue of chiropters!

Chiropters, more commonly known as bats, are one of the most endangered species on Earth, and fall victim every year to collisions with man-made structures. The movements of these small flying mammals, which use echolocation to find their bearings, are constantly disrupted by projects of all kinds (urban development, infrastructure, windfarms, etc). Time for Egis to step in!

Trajectography, an appropriate diagnostic tool

Bat3Data® is a digital cartography software solution that we designed to track and monitor the trajectories of bats in 3D. Developed in partnership with Cyberio, a start-up specialising in signal analysis, our tool deploys a geopositioned trajectory process based on two fundamental stages: the recording of sound emissions on the ground using sensors and the post-processing of the signals captured.

Through this process, the tool establishes an analysis of bat populations and movements on a given site, also distinguishing the species and flight paths of each individual in the area. But that’s not all: Bat3Data® goes even further by recommending the adequate measures to prevent collisions and design future urban infrastructure projects.

Plugged into a geographical information system (GIS), the solution reports the trajectories taken by bats and analyses them in reference to the constituent parts of a planned development. For example, when a structure is likely to prove harmful to bats, Bat3Data suggests corrective action.

Having received the judges’ special prize at the 2014 edition of the Entreprises et Environnement awards in the category “Biodiversity and Business”, the solution has been operational since 2013 and has been successfully tested on a range of infrastructure (most notably motorways A406 and A65). Its fields of application range from impact studies to environmental assessments and natural environment management. This is therefore a comprehensive tool which not only helps to fine-tune the design of eco-friendly development but also helps to protect biodiversity.

Maintaining ecological continuity in construction phase

Building work such as earthmoving can also disfigure the landscape structures used as flight corridors by bats. A gap of just a few metres in the linear objects used by these species to find their way may be enough to jeopardise or entirely prevent access to their different hunting zones or habitat.

As part of the project to build a road bypass around Troissereux in the north of France, we designed a temporary bat guidance system for use during construction phase. The Troissereux bypass is a 7-km dual carriageway which has the particularity of running between a bat reproduction site with lactating females and their hunting zone. To solve this issue, the final project featured an environmentally-motivated and ecologically transparent cut-and-cover section. The construction procedure however generated a trench and high embankments which were likely to significantly affect the colony, and so ecological continuity had to be maintained during works.

The temporary bat guidance system is made up of an assembly of cables and “acoustic beacons.” The spherical shape of these “lighthouses” amplifies the echolocation return signals of bats, enabling the animals to navigate through space, much like a lighthouse helps to guide boats. Positioned in 3D in the continuity of the bats’ flightpath which had been cut off by the earthworks, this system proved very effective in terms of reducing animal impacts.

This innovative initiative is cheap, lightweight and easy to implement on a work site. It was awarded the 1st Prize in the IDRRIM competition ‘Infrastructure for Mobility, Biodiversity and Countryside in the category “Ingenious Initiative”, in association with the Oise Department Authority, Bouygues TP Régions France, DTP, Colas Nord Picardie and Biositiv.

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