Europe’s Largest Bat Survey

As part of the mitigation strategy, the Bat Licence & Monitoring project was developed, playing a crucial role in preserving the forest’s rich history and protecting its local mammals. Pell Frischmann are carrying out a total of eight different day and nighttime surveys, along with data collection and monitoring over a period of five years during construction and an additional two years post-construction.

Pell Frischmann’s seven-year bat monitoring programme aims to secure the Favourable Conservation Status (FCS) of woodland bat species during and post construction. The collected data ensures that mitigation measures are effective and construction activities gain environmental approval at every stage.

The Bat Licence Monitoring Strategy, developed in 2017, originally relied on manual bat call identification. Since then, advancements in auto-identification technology have transformed the accuracy and efficiency of bat monitoring. Stratified quality assurance now prioritises hard-to-identify and rarer species, such as Bechstein’s, which are more sensitive to disturbance. This programme is led by Pell Frischmann’s Project Management and Environmental Teams, in collaboration with local ecological experts.

Pell Fischmann’s experts are providing the following services:

• Radio tracking;
• Habitat change monitoring;
• Light monitoring;
• Flight crossing surveys;
• Thermal imaging;
• Automated static detector monitoring;
• DNA faecal analysis;
• Noise & Vibration monitoring; and
• Weather Station monitoring

In 2022, during a period of major construction activity, the project conducted ultrasound measurements (8kHz–80kHz) to determine how bats might perceive sound generated by construction. Using high-frequency sound equipment, data were collected at various distances to simulate how bats would react to different activities.

These efforts addressed a major evidence gap in ecological assessment by delivering a breakdown of sound pressure levels from construction and comparing them to the audible range of bats. The outcome was a game-changing, evidence-based approach for assessing and mitigating ecological impacts.

Historically, some mitigation efforts have been overly cautious or unnecessarily costly. By utilising this data, this and other projects can now make smarter, more economical decisions, benefiting both wildlife and financial outcomes.

This innovative approach, engineered by Pell Frischmann, for collecting and analysing unweighted sound pressure level data, can be easily replicated across all types of construction activities. The method enables and promotes the creation of a data source that is accessible to others. Consequently, it reduces costs for the client, its contractors, and the wider industry, as it facilitates evidence-based impact assessment and more cost-effective mitigation design.