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Acoustic Bat Monitoring

High-tech and hands-off: New tools allow for rapid bat surveys statewide.


Image of AnaBat acoustic detector. The attached PDA (like a little computer screen) lets us view incoming bat calls instantly.Zoom+ AnaBat acoustic detector. The attached PDA (like a little computer screen) lets us view incoming bat calls instantly. © MacKenzie Hall
Echolocation

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.

Image of Captured by AnaBat: Examples of the call patterns made by four different bat species (eastern red bat, hoary bat, little brown bat, and tri-colored bat, from top left to bottom).Zoom+ Captured by AnaBat: Examples of the call patterns made by four different bat species (eastern red bat, hoary bat, little brown bat, and tri-colored bat, from top left to bottom).
Acoustic Detection

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.

Image of Erica Fischer (summer 2011 intern) mounts an AnaBat detector to the roof of a vehicle and waits for dusk.Zoom+ Erica Fischer (summer 2011 intern) mounts an AnaBat detector to the roof of a vehicle and waits for dusk. Jim Wright, N.J. Meadowlands Commission
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:
Download Mobile Acoustic Bat Survey Instructions

Mobile Acoustic Bat Survey Instructions - 69.9KB
Step-by-step instructions for volunteers conducting driving surveys with our AnaBat SD2 bat detectors.

Download Acoustic Transect Data Sheet

Acoustic Transect Data Sheet - 18.3KB
Mobile Acoustic Bat Survey data sheet to be completed with each survey.

Download Wildlife Conservation Corps Volunteer Form - Bats

Wildlife Conservation Corps Volunteer Form - Bats - 284.6KB
Bat survey participants should complete this form to become an official volunteer of the NJ Division of Fish and Wildlife.


Results:
Download 2014 Summer Bat Count and Mobile Acoustics Report

2014 Summer Bat Count and Mobile Acoustics Report - 526.2KB
Little brown bat populations continue to decline; big brown populations continue to increase.

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.

Download 2012 Mobile Acoustic Bat Survey Report

2012 Mobile Acoustic Bat Survey Report - 769.7KB
A summary of the statewide acoustic survey, with results and graphs.

Image of Seventeen unique driving routes were monitored in 2012.Seventeen unique driving routes were monitored in 2012.
Contact Us:

Stephanie Feigin, Wildlife Ecologist:


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