C-DRONE GUIDE · 26 JULY 2026
Environmental impact studies (wind, solar): the drone's role in wildlife and flora surveys, price
Before a wind turbine or ground-mounted solar farm can be built, a substantial file must show the site has been properly studied: the environmental impact study, a centrepiece of the authorisation file, rests largely on a naturalist survey conducted over a full biological cycle — breeding, migration, hibernation. The ecologists who run it have long worked with binoculars and ultrasonic bat detectors; increasingly they add a drone to reach ground the fieldworker cannot — cliffs, wetlands, canopy, building roof voids — and to map habitats at a scale field surveys alone cannot match. The drone does not replace the naturalist; it extends their reach. Here is what the regulations require, what the drone concretely brings to the survey, and prices observed in 2026.
Published on 26 July 2026, reviewed on 6 August 2026 — regulations in force as of August 2026.
What the regulations require
The requirement stems from the French environmental code (articles L.122-1 et seq., R.122-2): beyond capacity or footprint thresholds set out in an annexed table, a wind or solar project is subject to systematic environmental assessment — onshore wind farms also fall under the regulated-facility (ICPE) regime (heading 2980); below certain thresholds, a case-by-case screening decides whether the study is required. The file is then submitted for opinion to the environmental authority — the regional environmental authority board (MRAe) for most projects, a national panel for the largest — which issues a public opinion ahead of the public inquiry. The expected content follows a known sequence: baseline state of the site, analysis of foreseeable effects, then avoidance, reduction and, as a last resort, compensation measures (the "ERC" sequence), together with a monitoring scheme.
The naturalist strand of the baseline survey is the most fieldwork-intensive: it must cover a full biological cycle, generally a whole year, to capture migratory species and breeding and hibernation periods. Regional scoping guides recommend precise numbers of site visits — on the order of twenty-odd annual outings for birds and around a dozen for bats depending on the regional environment authority — and require, once the farm is operating, post-implementation monitoring starting within twelve months of commissioning. It is a long, demanding schedule, one the drone eases without shortening.
What the drone brings to the naturalist survey
The drone does not identify a species in the ecologist's place; it gives access to what cannot be observed from the ground. A very-high-resolution orthophoto and digital surface model map habitats — hedgerows, temporary ponds, woodland, grassland — with a precision and repeatability a ground GPS survey cannot match, in the spirit of our drone LiDAR vegetation mapping guide. The site's wetlands, often a major baseline issue, are pre-located as described in our wetland mapping guide; cliffs, quarries or building roof voids sheltering nests or bat colonies become inspectable without ropes or intrusion.
For the wildlife itself, an onboard thermal camera spots animals invisible in daylight at dusk or dawn, without approaching them on the ground — the method detailed in our drone wildlife counting guide. The scientific case for these uses is documented: a review by Chabot and Bird published in 2015 in the Journal of Unmanned Vehicle Systems catalogues unmanned-aircraft applications in wildlife research and management — optical monitoring, telemetry, habitat mapping — and highlights their value in reducing disturbance to animals compared with classic field methods (see the study on Google Scholar). The drone replaces neither listening points nor ultrasonic recorders: it adds a mapping layer and an observation capacity the naturalist folds into their own protocol.
A campaign paced to the biological cycle, not a one-off flight
Unlike a topographic survey or a construction-site photogrammetric flight, the drone mission for a naturalist baseline study is not a single outing: it slots into the ecologist's calendar of visits across the study's twelve months, with flights positioned at key periods — pre- and post-nuptial migration peaks, the breeding season, bats emerging from hibernation. Habitat mapping is generally redone two to three times a year to track vegetation phenology; thermal passes target the hours and seasons when the target species is most detectable.
This logic continues after commissioning: post-implementation monitoring, mandatory under the ERC scheme, often reuses the same drone protocol to objectify how site use evolves and how effective the compensation measures are — an exercise detailed in our ecological compensation monitoring guide. For a wooded area affected by the project, the survey is usefully complemented by a forestry component, described in our drone forest management guide.
Who it serves: renewable energy developers, consultancies, local authorities
The direct client for the drone component is most often the ecological consultancy commissioned by the developer to run the naturalist survey: it subcontracts the flights to a professional drone pilot while keeping control of the protocol and data interpretation. The wind or solar developer itself can be the direct client when the mapping data also serves the farm's technical layout — the same flight then serving both the impact study and the design stage, as touched on in our solar car park canopies guide for roof- and car-park-mounted solar. Local authorities sit on both sides: as sponsors of their own renewable energy projects, or as the authority consulted on files filed by third parties, where independent mapping can inform their opinion.
The same naturalist-monitoring logic applies beyond wind and solar strictly speaking: quarries, waste storage facilities and other industrial projects subject to impact studies share the same survey requirements — our quarries and waste storage facilities guides cover the operating side of these sites.
Observed prices in 2026
The drone component of an impact study is generally billed alongside the ecologist's mission, which remains the main line of the naturalist budget. Ranges observed in 2026 for the drone component alone (excl. VAT):
- Habitat and vegetation mapping (orthophoto + digital surface model, 20 to 100 ha site): €800 to €2,500 per campaign, redone two to three times a year.
- Dusk or night thermal pass (wildlife detection, bird or mammal counting): €400 to €900 per outing.
- Targeted inspection (cliff, quarry, roof void or timberwork to search for nests and bat colonies): €500 to €1,200 per site.
- Full annual programme (all passes over a biological cycle, pooled with the consultancy's calendar): generally €3,000 to €8,000 for the whole drone component, excluding post-implementation monitoring.
Post-implementation monitoring, required after commissioning, is generally billed as a fraction — 40 to 60% — of the baseline campaign, since the method and comparison points are already established. Request a quote stating the project type, site area and the impact study's schedule.