About this place
The Grotte de Gravelle National Nature Reserve is a small but ecologically significant protected site in the Jura department of France, located next to the village of Macornay, just 3 kilometers south of Lons-le-Saunier. Unlike sprawling landscape reserves, its importance has nothing to do with size — the entire protected area covers only 1.37 hectares — and everything to do with what lies beneath the surface.
What is actually protected here?
At the heart of the reserve is an underground cave, situated south of Macornay above the valley of the Savignard stream, a tributary of the Sorne river. This single cave is the entire subject of the reserve's protection: it was not established for any surface landscape or forest, but specifically for what happens inside its rock chambers.
Why was this cave protected?
The Grotte de Gravelle serves as a roosting site for colonies of bats — researchers have recorded 11 different species living there. Of particular importance is the presence of Schreiber's bent-winged bat, a species especially sensitive to disturbance and habitat degradation. Caves like this one function as both winter hibernation sites and breeding grounds, making their protection essential for maintaining bat populations across the wider Franche-Comté region.
How was the reserve created?
The nature reserve was formally established by a decree dated December 15, 1992. The classification proposal was initiated by CPEPESC Franche-Comté, an association dedicated to the study and protection of bats in the region. Following a framework agreement signed with the Prefect of Jura in August 1993, CPEPESC became the official manager of the reserve, a role the organization continues to hold today.
What conservation status does the site hold?
The Grotte de Gravelle is classified as a ZNIEFF type 1 site (registration number 0028 0004), the French designation for areas of significant ecological, faunal, or botanical interest. The reserve is also part of a network of sites protected under the European Union's Habitats Directive, specifically within the network of caves hosting Schreiber's bent-winged bat colonies across Franche-Comté. This places the site within a broader, cross-border effort to preserve bat habitats throughout Europe.
Can visitors explore the cave?
Because bat colonies are highly sensitive to disturbance — particularly during hibernation and breeding periods — access to the cave interior is strictly limited and controlled by the managing organization. Reserves of this kind, focused on chiropteran conservation, are generally not designed for casual tourist visits, and entering the cave requires authorization from the managing body.
Frequently asked questions
Where exactly is the reserve located? In the commune of Macornay in the Jura department, south of the village, above the Savignard stream valley, near Lons-le-Saunier.
How large is the reserve? It covers just 1.37 hectares, making it one of the smallest national nature reserves in France.
Who manages the reserve? The association CPEPESC Franche-Comté, under an agreement signed with the Jura prefecture in 1993.
What bat species live here? Eleven species have been identified, including Schreiber's bent-winged bat, a species of particular conservation concern.
Can the cave be visited? Access is restricted to protect the bat colonies — this is not a site set up for casual tourism.
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