Réserve naturelle régionale des grottes de Chenecey: Mapped Karst Landscapes and Protected Bat Habitats

The reserve has a relatively recent administrative history, shaped by changes in French environmental law and the strategic priority of protecting bat colonies in the Franche-Comté region. The 2002 'Démocratie de proximité' law transferred certain competencies to the regions and ended the validity of the'ancien 'Réserve naturelle volontaire' designation, causing three important bat sites to lose their protection status. This prompted CPEPESC Franche-Comté, working closely with the former Franche-Comté region, to explore the creation of a network of regional nature reserves specifically tailored to chiroptères and their habitats.

This effort culminated in the classification of seven regional nature reserves in 2015 and 2017, of which the Chenecey cave reserve was part, classified on 17 November 2017 under code RNR319 with CPEPESC Franche-Comté as the designated manager. The reserve was later covered by a unified management plan approved unanimously on 27 September 2019 by the standing committee of the Bourgogne-Franche-Comté regional council, providing the first five-year framework for the entire bat-cave reserve network.

On 12 December 2025, a new regional deliberation expanded the reserve's perimeter to include the Gouffre des Granges Mathieu, increasing the protected area to around 21.36 hectares and modifying the reserve's official name. This evolution reflects a continuing approach of reinforcing the protection of karst cavities identified as essential elements of the regional bat conservation strategy.

The reserve occupies a steep limestone cliff above the valley of the Loue, one of the most emblematic karst rivers of the eastern Jura. The Chenecey cave itself opens into this cliff face and develops a network of natural galleries richly decorated with concretions, characteristic of the limestone environments that shape much of the Doubs landscape. Above and around the cave entrance, the slope displays a mosaic of surface habitats typical of dry, sun-exposed calcareous terrain.

The surface mosaic includes dry grasslands in the European mesobromion and xerobromion styles adapted to the Jura context, vegetation of inland calcareous cliffs, and patches of beech woodland with Melica, alongside mesophilic edges and scrubby transitions. Together, these give the reserve its visually compact but ecologically layered character: a vertical landscape that moves from cliff-top dry grassland and beech woodland down through scrub to the dark entrance of a cave system that extends deep into the limestone substrate.

The more recent addition of the Gouffre des Granges Mathieu extends this landscape concept further, adding another subterranean void to the protected system while reinforcing the link between surface and underground environments that defines karst conservation in the region.

The ecological profile of the reserve is shaped by the coexistence of a subterranean environment with a calcareous cliff and dry grassland mosaic above it. A botanical survey conducted in 2019 by the Conservatoire botanique national de Franche-Comté identified more than two hundred vascular plant species and distinguished eleven phytosociological associations, seven of which carry particular conservation interest ranging from community-level to regional priority status.

Habitats of community priority interest include Central European dry grasslands on rocky debris, Mesobromion and Xerobromion communities of the French Jura, semi-dry mesoeuropean Bromus erectus grasslands, vegetation of inland calcareous cliffs, and beech woodlands with Melica. Mesophilic edges with regional interest complete the surface mosaic. Among the recorded vascular plants, the autumn lady's tresses orchid stands out as a legally protected species in Franche-Comté.

Typicality of these habitats is considered moderate overall, reflecting pressures from overgrazing, likely aggravated by the successive droughts of 2018 and 2019, and from scrub encroachment as open grasslands are progressively lost. These dynamics shape both the present conservation priorities and the future monitoring direction of the site.

The wildlife identity of the reserve is overwhelmingly defined by its bat fauna. The cave forms part of the broader network of cavities used throughout the year by the Schreibers' long-fingered bat, supporting it during hibernation, transit, and movements linked to its annual biological cycle. In autumn, around forty individuals of this species pass through the cave during transit, underscoring the site's role in regional connectivity between roosts.

Six species or species groups of bats currently use the cavity, with a predominance of species considered sensitive within the Franche-Comté context. Historically, ringing data from the 1950s recorded significant maternity colonies of the Mediterranean horseshoe bat in the cave; today this species, classified as critically endangered regionally, is still occasionally present. Both the greater horseshoe bat and the lesser horseshoe bat also use the cave for hibernation.

The reserve's management plan prioritizes six bat species for conservation: the Schreibers' long-fingered bat, the lesser mouse-eared bat, the Mediterranean horseshoe bat, the greater horseshoe bat, the lesser horseshoe bat, and the Geoffroy's bat. By protecting the cave and its wider network, the reserve indirectly sustains a far larger regional population of bats than its surface area would suggest.

The reserve's conservation significance derives primarily from its function within a regional network of caves dedicated to bat protection. The 2019 unified management plan identifies the preservation of cave functionality for six priority bat species as the central objective, and structures close to seventy concrete conservation actions around this goal. The plan was approved unanimously by the Bourgogne-Franche-Comté regional council, reflecting strong institutional support for the site.

The reserve sits within a layered framework of overlapping designations. It is part of a ZNIEFF type I area covering the grasslands and bocage of Chenecey-Buillon, a ZNIEFF type II area for the Loue valley between Ornans and Quingey, and both a Site of Community Importance and a Special Protection Area under the Natura 2000 network covering the Loue and Lison valleys. This stacking of instruments reinforces the protection of both the site itself and the surrounding ecological corridors.

Public access to the cave is restricted to the period between 1 April and 31 August, subject to authorization, because human disturbance during bat hibernation or summer roosting can cause mortality or force bats to shift to less suitable sites. Combined with efforts to control overgrazing and scrub encroachment on the surface habitats, these measures form the backbone of the protection strategy that gives the reserve its conservation value.

The reserve lies in a landscape that has long been shaped by traditional rural activities in the Loue valley, including grazing on dry calcareous slopes and small-scale woodland management. The presence of bocage elements recorded in surrounding ZNIEFF inventories reflects a long-standing pattern of mixed agricultural use on the fringes of the karst cliffs, an activity that continues to influence habitat quality today, sometimes through overgrazing and sometimes through progressive abandonment and shrub encroachment.

Local heritage is closely tied to the cave itself, which is known locally as a notable karst feature of the Loue corridor. The protected site sits within a broader Franche-Comté tradition of natural heritage appreciation, in which caves, cliffs, and bat colonies are recognized as elements of regional identity as well as ecological assets.

A key highlight of the reserve is the Chenecey cave itself, whose decorated galleries and bat-friendly microclimate make it a cornerstone of the regional bat conservation strategy.

Equally notable is the layered conservation framework that surrounds the site, combining regional nature reserve status with ZNIEFF and Natura 2000 protections across the Loue valley.

The integration of underground and surface habitats, from cliff-top dry grassland down through woodland to the cave interior, gives the reserve a compact but unusually rich ecological narrative for such a small area.

Given the cave's role as a sensitive bat roost, the period of tolerated public access runs from 1 April to 31 August, during which warmer temperatures and stable conditions make underground visitation more compatible with bat ecology. Spring and early summer are favorable for observing the limestone cliff vegetation, including the autumn lady's tresses orchid when in bloom later in the season.

Outside this window, the cave is closed to protect hibernating bats, and visitors interested in the broader landscape of the Loue valley can appreciate the reserve's setting year-round through the surrounding cliffs, dry grasslands, and beech woodland, although specific itineraries should respect any active conservation measures in force.