Acoustic Bat Monitoring
High-tech and hands-off: New tools allow for rapid bat surveys statewide.
In early 2010, the Conserve Wildlife Foundation purchased two AnaBat SD2 acoustic detectors to aid in bat research across the state. Acoustic detectors take advantage of a key bat behavior: echolocation. As bats fly, they are constantly giving off rapid, high-frequency pulses of sound (or “calls”). The sound pulses bounce off nearby objects and return to the bats’ ears as echoes, providing them with feedback about the size, shape, distance, and trajectory of those objects. Thus bats can navigate through the forest, avoid obstacles, swoop down for a drink of water, and hunt for insects in the total darkness of night.
For the most part, bat calls are ultrasonic – meaning they’re above the 20 kHz upper range of human hearing. So we can’t hear them, but an acoustic detector can. The AnaBat’s sensitive microphone can detect bats from up to 300 feet away, and a memory chip stores each bat call for later analysis. Since different bat species have unique call patterns that can be used to tell them apart, acoustic technology allows you to document the diversity as well as the abundance of bats in an area of interest.
With bats facing new and serious threats – like White-Nose Syndrome and the rise of wind turbines – there is an urgent need for bat population data. In the Northeast, most states are now including acoustic surveys in their toolkit. Detectors can be mounted on vehicles and activated while driving at night, making them a pretty quick and easy way to get a lot of information, all without having to catch, hold, or even see a single animal.
Putting Volunteers to Work
Most of our mobile acoustic surveys are now done by volunteers (we love you guys!). Volunteers are assigned a 10-30 mile driving route in their local area to travel twice each summer after dark. Between ours and the State's, we now have 4 bat detectors in circulation to keep the surveys moving.
There is currently a waiting list to volunteer for this survey.
Acoustic Survey Materials:
Mobile Acoustic Bat Survey Instructions - 69.9KB
Acoustic Transect Data Sheet - 18.3KB
Wildlife Conservation Corps Volunteer Form - Bats - 284.6KB
2014 Summer Bat Count and Mobile Acoustics Report - 526.2KB
2011 had been a trial year, with its fair share of trafficky suburban roads (Bergen County - eek) and impassable sand roads (Pinelands - yeesh). In 2012, we narrowed down the list of acoustic routes to 17 safe and manageable ones statewide. We had help from 32 volunteers to complete each route twice between June and July. These two months are the core of maternity season for bats, when we can safely assume that bats are active in their summer ranges (rather than migrating through an area). Thirty-three surveys were completed, amounting to 577 miles of bat recordings across New Jersey.
2012 Mobile Acoustic Bat Survey Report - 769.7KB
Stephanie Feigin, Wildlife Ecologist:
Find Related Info: Bats
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