East West Rail uses thermal drones for wildlife surveys

East West Rail (EWR) is now using thermal-imaging drones as part of its pre-construction ecological surveys. Working alongside contractor Kier, the rail developer aims to accelerate the process of clearing sites and reduce disturbances to wildlife, especially during archaeological trenching work.

This new method is being deployed on larger areas of land where ground-nesting birds are a particular concern. Qualified operators conduct the thermal surveys, with findings interpreted by Ecological Clerks of Works. These surveys can reportedly scan a site in two to three hours, identifying active nests and fauna such as brown hares and rabbit warrens that are not easily seen from the ground.

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Benefits for site clearance and planning

The practical advantage for engineers and environmental managers involved in infrastructure projects is clear. Early identification of nesting activity allows contractors to map ecologically sensitive zones. This enables targeted vegetation clearance and the design of buffer areas, permitting work to continue in unaffected parts of the site. EWR states this provides greater certainty in programme planning, particularly during the peak bird-nesting season between March and August, and reduces the need for site stand-downs and reprogramming.

EWR has reported successful detections including a crow's nest in woodland canopy and ground-nesting skylarks. Mammalian activity recorded by the thermal imaging has included brown hares and rabbits, along with the locations of their warrens. This information is intended to inform construction phasing, habitat management, and avoidance strategies.

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By embracing innovative technologies such as thermal drone surveys, we can identify and safeguard ground-nesting birds more effectively, giving our teams greater certainty to plan and deliver archaeological works responsibly.

Tristan Lincoln-Gordon, EWR director of environment

Tristan Lincoln-Gordon, EWR director of environment, stated that protecting the environment is fundamental to building East West Rail. He added that this technology helps safeguard ground-nesting birds more effectively, providing teams with greater certainty for responsible archaeological work. He also noted that the approach enhances ecological protection measures while improving efficiency and reducing disruption for the railway project.

EWR emphasises that the drones are part of a broader ecological mitigation framework and do not replace existing safeguards. Ecological Clerks of Works continue to oversee critical stages, conduct post-clearance verification surveys, and perform ongoing monitoring where buffer zones are maintained. The organisation also continues to engage with landowners and stakeholders.

Considerations for drone deployment

Several factors are important for teams using this type of drone deployment. These include understanding the detection limits and the need for expert interpretation of thermal imaging, which can be affected by ambient temperature, time of day, vegetation, and sensor resolution. Experienced ecological interpreters are essential to minimise false positives and negatives and translate detections into actionable constraints for contractors.

Regulatory and licence implications must also be considered. Detecting protected species does not remove legal obligations. Findings need to be integrated with statutory consenting timetables and mitigation commitments. Furthermore, drone survey outputs must be embedded into site logistics, work sequencing, and contractor workflows to achieve programme benefits, including contingency planning for follow-up ground checks.

Jonathan Pearce, Kier project director, commented that his company constantly seeks innovative ways to improve delivery and create value through safe and sustainable outcomes. He stated that East West Rail shares this forward-thinking approach, enabling them to develop solutions that enhance project performance and set higher standards for the wider industry.

Future implications for the sector

Thermal drones offer a method to reduce uncertainty on medium to large greenfield sites where ground-nesting birds can restrict excavation periods. For those planning archaeological investigations and initial earthworks, the technique can shorten the lead time for identifying ecological constraints and support more targeted mitigation design. However, the reliability of translating drone findings into reduced programme risk depends on equipment capability, survey timing, and ecological expertise.

As infrastructure projects increasingly adopt remote sensing tools, delivery teams are advised to set clear technical specifications for drone sensors, establish interpretation protocols, and define decision thresholds for when remote detections trigger further mitigation or licence applications. This ensures the technology complements existing ecological practice and statutory protections while delivering operational benefits.