Réserve naturelle régionale de la grotte de la Baume noire Protected Nature Reserve Geography

The cave of the Baume noire was first placed under formal protection in 1988, when it was classified as a voluntary nature reserve (réserve naturelle volontaire, RNV) under the management of CPEPESC Franche-Comté. This early status reflected growing awareness of the cave's value as a bat habitat.

In 2002, the so-called "démocratie de proximité" law abolished the voluntary reserve designation, and by 2006 the RNV status of the cave had lapsed. For several years, the site lost its dedicated protected-area regime, although a prefectural biotope protection order (arrêté de protection de biotope) was put in place to maintain continuity of protection, particularly alongside the nearby Grotte de la Baume at Échenoz-la-Méline. This interim safeguard prevented immediate degradation but did not replace the structured management of an RNR.

After this gap, CPEPESC Franche-Comté worked with the former Franche-Comté region to build a more systemic approach to bat cave protection. The result was a coordinated proposal to create a network of regional nature reserves dedicated to chiroptères and their habitats. Between 2015 and 2017, seven such reserves were created, of which the grotte de la Baume noire was classified on 24 September 2015. In 2015 and again in 2017, CPEPESC was formally designated as the manager of the overall network. A unified management plan covering the chiroptère cavity reserves was adopted unanimously by the Bourgogne-Franche-Comté regional council in September 2019, providing the first five-year framework for coordinated action across the network.

The reserve lies on the wooded southern flank of the Monts de Gy, a low limestone plateau in the Haute-Saône département. Topographically, the site is defined by a single hill just south of the village of Fretigney-et-Velloreille, dominated by the entrance funnel of the Baume noire cave and the forest that surrounds it.

The geological setting is Jurassic limestone of the Bathonian stage. This soluble rock has produced the karst landscape that defines the underground environment, with a steep collapse cone of rock debris (éboulis) descending beneath an imposing entrance porch into a long, roomy cavern. From the entrance hall, a network of natural galleries extends for roughly one hundred metres, forming the physical core of the protected site.

Above ground, the protected landscape is small but well-wooded, consisting of collinar oak-hornbeam forest and beech forest with sweet woodruff, typical of the middle-elevation forests of eastern France. The broader forest mass of the Monts de Gy extends far beyond the reserve boundary and provides the wider ecological context that gives the small protected area its meaning.

The natural character of the reserve is defined by two strongly contrasting but interconnected habitats: a subterranean karst environment and the temperate deciduous forest that mantles the hillside above it. The cave operates as the focal ecological feature, while the surrounding woodland acts as both a buffer and a complementary habitat.

Inside the cave, conditions are cool, stable, and humid, supporting the bat species that use the site throughout the year. The entrance area, with its cold microclimate, is particularly valuable for fissure-dwelling bat species such as the western barbastelle. Beyond the cave, the protected oak-hornbeam and beech forests on the slope are typical habitats for forest-dwelling bats and other woodland fauna, and they are part of a much larger forest complex extending across the Monts de Gy.

The reserve is inscribed within a coherent regional ecological network of underground sites chosen to maintain viable bat populations. Within this network, the cave functions as both a critical hibernation site and a transit site, supporting the movement and seasonal separation of bat colonies across the broader landscape.

The wildlife profile of the reserve is dominated by bats. Thirteen species or species groups are known to use the Baume noire cave, making it one of the more bat-diverse underground sites in the region. Conservation interest is concentrated on species that depend heavily on stable cave conditions, particularly across the hibernation period.

The signature species is Schreiber's bent-winged bat (Miniopterus schreibersii). The cave holds what is considered the largest known hibernation colony of this species in Franche-Comté, with close to 10,000 individuals recorded during winter counts. The cave also hosts a major hibernation complex for the greater horseshoe bat (Rhinolophus ferrumequinum), together with a nearby cave, averaging around 300 individuals. The cold microclimate of the cave entrance makes the site especially suitable for the western barbastelle (Barbastella barbastellus) and other fissure-roosting bats.

Beyond bats, the forest around the cave supports broader woodland fauna associated with the larger Monts de Gy forest mass. While the public focus of the reserve is on its chiropteran inhabitants, the surrounding woodland contributes to maintaining ecological continuity for other forest species in the area.

The reserve exists primarily to maintain the long-term functionality of the Baume noire cave as a bat roosting site and to protect the immediate forest environment that supports it. Because it is part of a multi-site network rather than a stand-alone site, its conservation value is closely tied to the coordinated management of caves across the region.

Legal protection rests on a layered set of instruments. A prefectural biotope protection order issued in 2007 secures the cave as a habitat, and the 2015 regional nature reserve classification (RNR296) added a stronger management framework. The cave is also designated as a Natura 2000 Special Conservation Area within the site 'Réseau de cavités à Minioptère de Schreibers', and the broader forest landscape is covered by ZNIEFF type II 'Les Monts de Gy' and a ZNIEFF type I entry for the cave itself.

The overarching conservation objective, set out in the 2019 network management plan, is to preserve the functionality of the cave network for six priority bat species: Schreiber's bent-winged bat, the lesser mouse-eared bat (Myotis blythii), the Mediterranean horseshoe bat (Rhinolophus euryale), the greater horseshoe bat, the lesser horseshoe bat (Rhinolophus hipposideros), and Geoffroy's bat (Myotis emarginatus). Roughly seventy concrete actions, covering monitoring, habitat management, and public outreach, are organised around this aim, with additional attention given to protecting the surrounding forest habitats.

Public access to the cave is prohibited year-round, because even minimal disturbance during hibernation or maternity seasons can cause bat mortality or force colonies to abandon otherwise suitable sites.

The reserve holds modest but real cultural significance as part of the regional heritage of karst landscapes in Franche-Comté. Caves like the Baume noire have long been part of local geographic and vernacular knowledge, and the Baume noire stands out locally because of its size and the dramatic character of its entrance porch.

The site is also meaningful within the modern culture of nature conservation in the region, as a flagship example of how small, targeted reserves can play a major role in species protection when coordinated across a network. The work of CPEPESC Franche-Comté, the site's long-term manager, has helped embed bat conservation into the regional identity of environmental stewardship in Bourgogne-Franche-Comté.

A compact 19-hectare reserve whose exceptional conservation value rests on a single, well-protected karst cavity. The Baume noire hosts one of the largest known hibernating colonies of Schreiber's bent-winged bat in Franche-Comté, with close to 10,000 individuals. The cave supports roughly 300 greater horseshoe bats during winter as part of a linked cave complex, and is one of thirteen bat species records for the site. It anchors part of a regional Natura 2000 site dedicated to protecting the network of cavities used by Schreiber's bent-winged bat throughout its annual cycle.

The reserve itself is closed to the public at all times, and the cave is never accessible to visitors. Anyone interested in learning about the site or its bats is best directed toward the outreach materials produced by CPEPESC Franche-Comté and the general interpretive resources of the Bourgogne-Franche-Comté regional nature reserve network. Any visit to the wider Monts de Gy landscape is most rewarding in spring or early autumn, when the oak-hornbeam and beech forests typical of the area are at their most expressive, though the cave itself remains off-limits year-round.