Olsson Associates


Olsson scientists monitor for listed bat species

Thursday, July 14, 2016

Linda Van Hoosen, Communications

For many people, bats invoke the image of old vampire movies or they are nuisances that get into your attic. However, bats are a valuable part of our environment. Some species are rare and protected by federal law. The Environmental team at Olsson Associates offers bat acoustic monitoring to clients who need to know which species live and migrate within the scope of their projects.

Most bats are a natural form of pest control because they eat insects such as mosquitos. Olsson environmental scientists Amy Oden and Paige Anderson recently monitored for bats on the roof of an Olsson office to verify equipment operation and settings prior to deployment at a project site. Unlike birds or other wildlife, bats use discrete pulses of sound that are almost completely above the typical human range of hearing. Special acoustic detectors must be used for bat detection.

These detectors are commonly used to evaluate bat species present; often, the focus is on presence of threatened and endangered bat species such as the northern long-eared bat and Indiana bat. 

“We use acoustic detectors that can capture ultrasonic frequencies,” Amy said. “We put microphones at varying heights depending on the project and project monitoring goals. At night, the detectors turn on and record any high-pitched noise.”

Northern long-eared bat



The sound files collected from the monitoring sessions are put through acoustic analyzers that identify species based on sound characteristics. Automated species identifications are also often manually inspected by Olsson environmental scientists for accuracy.


 Big brown batMost project applications are in a much more natural setting than an urban roof. However, during the weekend test from Olsson’s rooftop, Amy says the acoustic detector picked up calls of big brown bats, hoary bats, and silver-haired bats. Big brown bats are  commonly found in crevices of human structures.  Hoary bats and silver-haired bats can be found roosting  in trees and may have been drawn to the area by  insects flying around street and building lights. 


Hoary bat

The acoustic monitoring of bats provides clients needed  information about the activity and presence of bat  species to assist with project planning and species  conservation.






 If you would like more information about acoustic bat  monitoring, contact Amy Oden at 402.458.5020 or Paige  Anderson at 402.458.5039.

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