Ultrasonic Monitoring

What is ultrasonic monitoring?

Ultrasonic monitoring focuses on capturing high-frequency sounds produced mainly by bats, as well as some insects and small mammals.
These frequencies (typically 20–120 kHz) are beyond human hearing and require specialised recorders and classification algorithms.

Within WildSense, ultrasonic monitoring provides detailed information on bat behaviour, habitat use, activity levels, and community composition — filling an ecological gap that cannot be captured by visual or standard acoustic methods.

Devices we use

Ultrasonic surveys within WildSense rely on several field-tested devices:

AudioMoth (ultrasonic mode)

• Low-cost and highly portable
• Widely used for both research and large-scale bat surveys
• Configurable sampling rates suitable for bats

Bat-specific detectors

• Higher-fidelity devices for detailed call structure
• Used where species-level identification is critical
• Ideal for long-term monitoring plots

Custom UKCEH recorders

For research trials within AMBER and related programmes.

Together, these devices support a broad range of ultrasonic recording scenarios — from bat passes to full-night activity profiles.

Why ultrasonic monitoring matters

Bats are key bioindicators and respond rapidly to environmental change. Ultrasonic monitoring allows us to:

• Assess bat activity levels, guilds, and community structure
• Understand how bats use landscapes (foraging, commuting, roosting)
• Evaluate impacts of habitat change, land management, and restoration
• Monitor protected sites or infrastructure projects
• Detect shifts in bat populations under climate change

Ultrasonic methods provide:

• Continuous, non-intrusive monitoring
• High temporal resolution
• Large sample sizes
• Standardised long-term datasets

These datasets are invaluable for conservation, policy evaluation, and ecological modelling.

How the system works

Recording

Ultrasonic sensors are deployed from sunset to sunrise, capturing:

• echolocation calls
• social calls
• feeding buzzes
• background ultrasonic soundscape

Devices record overnight for extended periods, producing thousands of call sequences.

Data processing

Ultrasonic recordings are processed through:

BTO Bat Classification Pipeline

The primary workflow used across WildSense projects, supporting:

• species-level identification where possible
• guild-level classification
• call quality filtering
• activity metrics

Internal UKCEH workflows

Used for:

• clustering by call type
• exploratory analysis
• bespoke research questions in AMBER and partner projects

Open-source tools

Where appropriate, e.g. for visualisation or supporting species not covered by standard models.

Outputs include:

• species/guild detections
• nightly activity indices
• foraging behaviour markers
• spectrogram-derived summaries

Where we use ultrasonic monitoring

Ultrasonic deployments support:

• woodland and farmland bat surveys
• tropical forest bat research (AMBER)
• protected area monitoring
• habitat restoration assessments
• long-term baseline establishment for ecological change studies

As WildSense develops, ultrasonic datasets will integrate more deeply with imagery, EO products, and multi-modal biodiversity indicators.

Images & media

Place images in:

docs/systems/ultrasonic/images/

Example:

Partners & collaborators

Ultrasonic monitoring is supported by:

• UK Centre for Ecology & Hydrology (UKCEH)
• British Trust for Ornithology (BTO) – bat call pipeline
• Additional academic and conservation partners

Get involved / learn more

Add deployment guidance, bat pipeline documentation, and links to call classifiers here.

Example outputs

• Bat activity indices over nights, weeks, or seasons.
• Species-level or guild-level detections.
• Echolocation call sequences and spectrogram summaries.