Monitoring and Researching Bat Activity at Wind Turbines with Videography

Science Center Objects

The rapid expansion of wind energy nationwide is an important step toward reducing dependence on non-renewable sources of power.  However, the magnitude of the wildlife impacts at wind energy facilities is a newly recognized threat, and the cumulative long-term impacts to various bat species are of increasing concern.  It is estimated that more than 450,000 bat fatalities now occur each year at wind turbines in the U.S. and Canada (Cryan 2011).

Overview: 

Cryan turbines

Wind turbines on O'ahu, Hawai'i.Photo: P. Cryan  

The rapid expansion of wind energy nationwide is an important step toward reducing dependence on non-renewable sources of power.  However, the magnitude of the wildlife impacts at wind energy facilities is a newly recognized threat, and the cumulative long-term impacts to various bat species are of increasing concern.  It is estimated that more than 450,000 bat fatalities now occur each year at wind turbines in the U.S. and Canada (Cryan 2011).

Assessing the risk industrial wind turbines pose to bats is hindered by low light conditions and the cryptic attributes of night-flying animals.  With modern wind turbines now reaching as high as 150 m above the ground (equivalent to a 50-story building), there is presently no cost-effective standards for survey methods available for observing and measuring bat occurrence and behavior in the dark at heights and distances relevant to assessing wind-turbine risk.  For example, radar and thermal imaging systems cannot always differentiate the types of animals being detected, and ground-based acoustic detectors can only sample up to about 40 meters, well below the turbine rotor-swept zone in which bats and birds are struck.

Monitoring high-flying nocturnal animals that occur intermittently requires sampling sessions of long duration.  This need is often best met by deployment of remote technologies, particularly in situations that are unsafe for long-term occupancy by human observers (e.g., offshore environments and airstrips).  A major challenge of such technological approaches is developing efficient ways to process and interpret the large amounts of data acquired.  Video-based monitoring systems show great promise for monitoring flying nocturnal animals over entire nights and seasons.  Motion analysis of digital imagery acquired by thermal infrared cameras has proven effective for quantifying night flights of bats emerging from caves, and thermal cameras have also been used to observe bat activity around turbines, but the techniques have not been combined as yet in an analytically tractable and cost-efficient system for long-term deployment.  Our project is working toward producing standardized methods and tools that meet the challenges of successfully measuring bat activity and risks in association with wind turbines and in assessing and predicting bat mortality in conjunction with quantitative models based on improved surveys.

 

Dr. Frank Bonaccorso removes a Hawaiian hoary bat from a mist net

Dr. Frank Bonaccorso removes a Hawaiian hoary bat from a mistnet. Photo: J. Jeffrey

Project Objectives: 

We propose to demonstrate a near infra-red (NIR) video system coupled with advanced digital processing and tracking algorithms to process target information for the purposes of assessing nocturnal animal occurrence and behavior.  The system will include automated data processing to reduce the burden from imagery review.  We will apply the NIR video system to a range of field settings, and validate the approach of detecting and tracking distant cryptic targets for use in monitoring of vertebrate populations.  Specifically, we will demonstrate the application of very low-light cameras in combination with NIR illumination.  Near-infrared illumination is a suitable lighting source because this wavelength range is not visible to vertebrates and will not affect behavior.  Infrared cameras can also image through glass and other clear materials, whereas thermal IR cameras cannot and thus, the NIR system is better suited to weatherproof enclosures for long-term deployment (e.g., marine environments of offshore turbines).

This is the first field validation of NIR videography to nocturnally track and quantify target motion in mixed species settings at distances >100 m, and under realistic operational conditions and long-term deployment scenarios.  The method will provide a cost-effective means to track animal activity, assess abundance and detect specific events of interest (e.g., fatality incidents at wind energy facilities; seabird disorientation and “fallout” at bright light sources; etc.).  We expect the experimental and numerical endeavors of this work to quantify previously unexplored aspects of nocturnal animal behavior, and to produce information that may be used to reduce detrimental effects of human activities to wildlife.