As part of the Recovery Plan, the restoration of Saint-Arnoux Cathedral was able to be done by combining conservation of a historic monument and nesting spaces of protected bird species.
Emblematic monument of the Hautes-Alpes, the Saint-Arnoux cathedral, located in Gap, was built at the end of the 19th century according to the plans of architects M. Laisné and M. Goulain. Consecrated in 1895, it was declared a historical monument on August 9, 1906.
Yann Visseaux, Heritage Engineer in charge of the department of Hautes-Alpes and Emilie Avizou, in charge of the Recovery Plan, both agents in the Regional Conservation of Historical Monuments of the Regional Direction of Cultural Affairs Provence-Alpes-Côte d'Azur (DRAC PACA) provide us with some details on the ongoing work and the impact of the ecological approach on the protection of nestings.
The restoration of the roofs will allow to put out of water the cathedral and thus to protect its structure from degradation and embrittlement that could be accelerated by the contact of water, gels and by consequence to ensure the safety of the public.
The initial date of the start of construction was postponed following the completion of an ecological diagnosis attesting the presence of protected bird species (rock and window swallows, swifts, kestrel falcons) in the immediate environment of the cathedral. In order to preserve nesting, the DRAC PACA called on the Ligue Protectrice des Oiseaux (LPO) to consider so-called compensatory measures, having the least possible impact on the existing ecosystem.
'We knew there were protected species on the site. The LPO was quickly contacted so that we could find alternatives. The representatives accompanied us in the preparation of the application for exemption from the prohibition of the destruction and disturbance of habitats of protected individuals and species. '
After work in 2010 (consolidation of the vault of the choir and interior of the chapel Saint-Arnoux), a diagnosis in 2014 revealed the need for restoration of facades and covers. After the facades, there remained the covers whose restoration, slightly initiated, was confirmed by the arrival of the Recovery Plan.
The mastermind of this project is Michel Trubert, Chief Architect of Historical Monuments territorially competent. Two phases of work are planned:
• A firm slice covers the nave, transept and aisles
• An optional slice concerns the bedside.
The appropriations received to carry out this operation amount to EUR 1.4 million.
Portrait of the recovery: Saint Arnoux Cathedral in Gap (05)
Protection of the species present on the site, intervention of the LPO
By ministerial incentive, biodiversity must be taken into account when renovating and restoring historic monuments. There are more and more examples, and in our region as well.
Can the species present in the building not be detrimental to its structure and conservation?
This is always the problem, there are always several regulations and concerns that intersect. Indeed, bird droppings can alter the stone. We must cross paths and take sides. A balance must be struck between preserving the site and preserving the species.”
In the case of the cathedral of Gap, due to the presence of protected species (swallows of window and rock, black swifts, kestrels), a derogation to this protection (prohibition of destruction and disturbance of habitats) is required to perform the work. A number of recommendations have been imposed by DREAL, the instructor of the exemption application file: reduction measures (access to natural nests, artificial nest boxes and reconstruction of nests), compensatory measures (replacement of nests and creation of nesting site of black swifts) and accompanying and monitoring measures (study of bats, ecological accompaniment during the work and monitoring at the end of the work).
La Ligue Protectrice des Oiseaux: interview with Valérie Vincent and Michel Vergès
Valérie Vincent and Michel Vergès, active members of the association LPO PACA, intervening in support and advice to preserve biodiversity in the city on the site of the Saint-Arnoux Cathedral of GAP, lent themselves to our questions.
"The installation of temporary nesting boxes for swallows is a first in France. We hope that this project initiated by the DRAC PACA will serve as an example and springboard for others.'
As volunteer members of the LPO, our primary mission is to preserve biodiversity. We are working to reconcile this necessary preservation with all the problems encountered in buildings, whether modern or old. The small fauna of buildings must be able to continue to exist despite the specificities and constraints that may exist when working on a Historical Monument, for example.
What led us to intervene in this case is a real opportunity. For years, local LPO groups have been sensitive to biodiversity loss. We are working with some national and international organizations to conduct inventories to better measure the state of biodiversity and its evolution. Through these inventories we identify the sites of our sector, in this case the Gapençais basin, and these follow-ups lead us to note the loss or decrease of colonies in place for various and varied causes: tree cutting, demolition and/or renovation work… The loss of species is visible in the urban environment. Our desire is to intervene upstream, in order to detect the projects that will take place and to contact the managers to explain to them the stakes of the sites for which they are responsible, how to manage them while preserving biodiversity, the cost of such measures. We seek to offer them technical solutions. We have expertise as experts in biodiversity, some of us are volunteers, but we can also put developers, if they wish, in touch with our network of professionals. We have created a network called U2B (Urban Planning and Biodiversity) whose purpose is to connect planners, be they project managers, architects, local authorities, government departments, construction companies, etc. and exchange regulatory and technical information for the management of worksites so that they master certain essential constraints. The periods of feasibility of the works according to the season, in particular not nesting for birds or not present for migrants, technical solutions upstream of the site, costs… We have a real desire to make them aware of biodiversity and its issues, because it is a pressing need.
Regarding the Saint-Arnoux cathedral, our collaboration began during the renovation of the facades in 2020. Mr. Visseaux had contacted the OFB in Gap following the discovery by the companies of swallow nests. In consultation with DREAL, we provided advice. The DRAC had taken special care not to destroy swallow nests.
In 10 years in France:
The Black Swift population decreased by 47%
The Swallow population has decreased by 34%
In 2021, following the funding of the Recovery Plan, Mr. Visseaux contacted us to find out how to successfully conduct the work within the time frame set by the plan. that is, during the nesting period while preserving species on site by limiting the impact of the work on reproduction. In order to do so, a waiver request was filed with the DREAL PACA and submitted to the NISC. It is a good idea to contact an environmental association. The commitments made by the DRAC concerning the preservation of species allowed the request for derogation to be accepted by the Commission. This request included measures for reducing impacts and for conservation, such as the installation of various temporary nest boxes depending on the type and number of protected species present (accessible during work), but also an organization of the installation and arrangement of scaffolding. At present, 50% of natural nests remain accessible but only 10% are used when scaffolding impedes access. Despite the disturbance associated with the work, the colony is present and active and the artificial nests have a relative success.
In October 2021, the LPO organized an information meeting with Mr. Visseaux, Mr. Passavy, Ms. Tognini, Mr. Gascuel and a representative of the OBF to present the issue to government services. Indeed, our main request was to respect the Obviously period, that is to say the postponement of work outside the nesting period, that is between mid-October and mid-April. It should be noted that we have advised against measures to reduce the impact or even a compensatory policy to which the DRAC PACA subscribed. In case of destruction of a natural nest, it must be replaced by an artificial nest box in the same place to offer the species the same possibilities as before works. To date, we have not experienced any destruction on this site for this part of work. Since it is a Historical Monument, it is possible to install the artificial nest box near the destroyed nest to also preserve the building. We have to find the right balance between preserving the building and preserving biodiversity. It’s all about adaptation and exchange. We are associated with the monitoring of this project. Moreover the study office ASELLIA Ecology, specialized in bats, writes the reports to the DREAL taking into account our observations.
Currently at GAP, we are working on a project with similarities. It is an old industrial-type monument, the old silos. There is a real conversion project under way. Are present on the site of swallows, swift and bats. The work will extend over 3 years. The method of preservation chosen is very similar to that of the cathedral. The destruction of the building is done gradually, the natural nests destroyed are replaced by artificial nest boxes, as the site evolves, in order to minimize the impact and disturb the species as little as possible. A mud pond was also installed to promote the construction of swallow nests. This gives birth to a small ecosystem, as in Saint Arnoux, with the arrival of many insects… a pantry that comes at the right time for our volatile friends. On the site of the Cathedral, they have a real success. Before the mud pools were completely filled, insects were already proliferating: wasps, butterflies, flies… This requires frequent maintenance. At least once a week, we will replenish them with water, especially at this time with the drought we are experiencing.
We are trying, in a way, to accompany the evolution of the city in order to limit the flight of colonies of swallows either because of the destruction of their natural habitats or the decrease of their food resources. If the surrounding food runs out, we will have losses on births and colonies could move elsewhere. The idea remains to preserve their autonomy, most of what is put in place is provisional, we should not replace them in the construction of their habitat or its maintenance.
In PACA, one of the cities most involved in the preservation of biodiversity is the city of Toulon labeled «Ville Nature» in 2017 for its action towards swifts that are integrated in urban planning documents. We can also mention Hyères and Seyne-sur-Mer and Embrun for the Hautes Alpes.
We have different hats: first, we are whistleblowers. We warn, more or less, in an emergency, depending on whether or not we have been informed upstream of work sites, of the presence of protected species. We must also warn entrepreneurs of the legal risks they face by not taking adequate precautions to preserve the protected species present. Then we have a role of support and advice, then finally we provide a volunteer form of accompaniment throughout the construction site. Our successive inventories are important for post-site monitoring. Often, developers must hire a Design Office that will follow up with the State services over a minimum period of three years when the work is completed.
Unlike a professional design office, as an association, we have the advantage of being available and familiar with the sectors identified, which brings an interesting complementarity for the professional ecologist.
However, we do not become legally responsible for the smooth running of the reduction or compensation measures, it is the developer who remains responsible for his work and the protection of species.
Although the ideal remains avoidance, we would like to thank the Ministry of Culture and more specifically the DRAC PACA and UDAP 05 for playing the game of transparency so that we can carry out this observation work. We are thus accumulating knowledge that will benefit everyone.
The thing to keep in mind is that in a negotiation everyone loses. The important thing is to arrive at a compromise that can satisfy the various parties, minimizing the consequences at all levels in the fairest possible way: financial, time, built and of course biodiversity...
