There are many efforts across North America to monitor bats using acoustic detectors, in order to better understand bat biology, the impact of various threats - such as wind turbines - on bats, and to get a baseline measurement of bat populations.
Bats use high frequency sound pulses to help them navigate their environment and find prey. This is known as echolocation. Bat detectors take advantage of these echolocation calls by listening for bats at a given location. Depending on the degree of post-processing of the echolocation recordings and species involved, it is sometimes possible to determine which bat species were near a given detector on a given night.
When you aggregate this information up across many detectors over large areas and longer time periods, you can start to build an understanding of where different species of bats are located throughout the year. While some species hibernate in caves and are thought to become much less active during winters in the northern hemisphere, other bats migrate over large regions. However, these migration patterns are poorly understood, in part due to the difficulty in tracking bats throughout the season. Using large numbers of acoustic detectors across the continent is essential for improving our scientific understanding of these migration patterns.
Likewise, if you use a consistent approach to capturing this information over large areas, you can start to build statistical models of where bats are likely to be present or not. Over time, if you capture this information repeatedly, you can start to understand the trends in this likelihood, and therefore determine whether or not bats are increasing or decreasing in their use of broad areas of the landscape. This information is critical for detecting and responding to the impacts of various threats on bat populations, such as diseases like white-nose syndrome.
Given the high value in centralizing bat acoustic monitoring data over large areas, using data from many different contributors, there have been multiple efforts to create centralized databases at the regional and continental level.
In November 2019, I helped lead this workshop to define a more cohesive vision for a continental-scale bat acoustic monitoring system that leverages these existing efforts, while streamlining the data processing requirements for data contributors. Specifically, we mapped out ways to integrate the Bat Acoustic Monitoring Portal with the North American Bat Monitoring Program, and plan toward ways to integrate with cloud-based bat data processing capabilities currently under development by Bat Conservation International and Conservation Metrics, Inc.
The Bat Acoustic Monitoring Portal is an effort led by the USDA Forest Service, and is built using the Data Basin platform to enable user-uploaded data. Launched in 2013, many bat biologists have shared their data using this system. We recently launched a companion tool, the Bat Acoustic Monitoring Visualization Tool, which showcases some of these data and highlights the great value in centralizing acoustic monitoring data.
The North American Bat Monitoring Program is an ambitious, multi-scale effort led by the U.S. Geological Survey to bring together several different types of bat monitoring data across the continent to develop a better understanding of the current status and trends of bat populations. A key component of this effort is the use of a systematic, repeatable sampling approach that will allow scientists to develop statistically rigorous analyses of bat occurrence across large areas. More recently, this program has launched a data portal that allows users to upload their monitoring data.
Bat Conservation International and Conservation Metrics are working on exciting new ways to process massive amounts of acoustic monitoring data using cloud-based data pipelines. They've discovered that the desktop-based, manual approaches used in the past for analyzing bat acoustic data can no longer keep up with the increasing volumes of data being collected across the continent. These new approaches promise to liberate individual bat data contributors from some of the laborious tasks required to be able to share their data into centralized systems like those listed above.
This workshop was a pivotal step in aligning the goals between these efforts toward a larger, shared vision. While the next steps for aligning these systems will take several months to complete, all participants of the workshop came away with clearly defined next steps to move us toward these broader goals.
Over the long term, our efforts will contribute toward a better understanding of bat biology, a better understanding how bats move around over space and time, and a better ability as a society to safeguard the long-term viability of bat populations across the continent.