Bats play crucial ecological roles and provide valuable ecosystem services, yet many populations face serious threats from various ecological disturbances. The North American Bat Monitoring Program (NABat) aims to use its technology infrastructure to assess status and trends of bat populations, while developing innovative and community‐driven conservation solutions.
Here, we present NABat ML, an automated machine‐learning algorithm that improves the scalability and scientific transparency of NABat acoustic monitoring. This model combines signal processing techniques and convolutional neural networks (CNNs) to detect and classify recorded bat echolocation calls. We developed our CNN model with internet‐based computing resources (‘cloud environment’), and trained it on >600,000 spectrogram images. We also incorporated species range maps to improve the robustness and accuracy of the model for future ‘unseen’ data. We evaluated model performance using a comprehensive, independent, holdout dataset.
NABat ML successfully distinguished 31 classes (30 species and a noise class) with overall weighted‐average accuracy and precision rates of 92%, and ≥90% classification accuracy for 19 of the bat species. Using a single cloud‐environment computing instance, the entire model training process took <16 h.
Synthesis and applications. Our convolutional neural network (CNN)‐based model, NABat ML, classifies 30 North American bat species using their recorded echolocation calls with an overall accuracy of 92%. In addition to providing highly accurate species‐level classification, NABat ML and its outputs are compatible with Bayesian and other statistical techniques for measuring uncertainty in classification. Our model is open‐source and reproducible, enabling future implementations as software on end‐user devices and cloud‐based web applications. These qualities make NABat ML highly suitable for applications ranging from grassroots community science initiatives to big‐data methods developed and implemented by researchers and professional practitioners. We believe the transparency and accessibility of NABat ML will encourage broad‐scale participation in bat monitoring, and enable development of innovative solutions needed to conserve North American bat species.
We conducted a spatially explicit study of bat foraging activity in the terrestrial coastal habitats of the eastern Kenai Peninsula along the northern Gulf of Alaska. We confirmed the species and presence of foraging bats within these coastal habitats using spectral analysis from 24 automated acoustic recording devices that captured 24,058 recordings of bat vocalizations across 1,332 acoustic survey nights between June and September (2018–2 022. We used machine learning (TreeNet) to model and map the spatial relationship of bat foraging behavior and six habitat types (conifer forest, subalpine shrubland, water, barren, herbaceous meadows, and alpine). Bats foraged in areas close to fresh waterbodies with moderately sloped terrain along southwestern to north-facing aspects ≤ 50 m from conifer forests, < 150 m from the coastline, and at elevations < 200 m above sea level. These coastal habitats were largely discontinuous, but extensively distributed as a patchwork along the eastern Kenai Peninsula. Our model highlights specific areas where strategic planning and hypothesis-based research can be focused. Our results fill a fundamental data gap in this understudied region of Alaska that provides a foundation for proactive research, partnerships, and conservation as white-nose syndrome presents an eminent threat to bats inhabiting coastal habitats along the North Pacific.
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