Original Paper

Biodiversity and Conservation

, Volume 16, Issue 14, pp 4081-4093

First online:

Psychoacoustic sampling as a reliable, non-invasive method to monitor orthopteran species diversity in tropical forests

  • Swati DiwakarAffiliated withCentre for Ecological Sciences, Indian Institute of Science
  • , Manjari JainAffiliated withCentre for Ecological Sciences, Indian Institute of Science
  • , Rohini BalakrishnanAffiliated withCentre for Ecological Sciences, Indian Institute of Science Email author 

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We evaluated trained listener—based acoustic sampling as a reliable and non-invasive method for rapid assessment of ensiferan species diversity in tropical evergreen forests. This was done by evaluating the reliability of identification of species and numbers of calling individuals using psychoacoustic experiments in the laboratory and by comparing psychoacoustic sampling in the field with ambient noise recordings made at the same time. The reliability of correct species identification by the trained listener was 100 % for 16 out of 20 species tested in the laboratory. The reliability of identifying the numbers of individuals correctly was 100% for 13 out of 20 species. The human listener performed slightly better than the instrument in detecting low frequency and broadband calls in the field, whereas the recorder detected high frequency calls with greater probability. To address the problem of pseudoreplication during spot sampling in the field, we monitored the movement of calling individuals using focal animal sampling. The average distance moved by calling individuals for 17 out of 20 species was less than 1.5 m in half an hour. We suggest that trained listener—based sampling is preferable for crickets and low frequency katydids, whereas broadband recorders are preferable for katydid species with high frequency calls for accurate estimation of ensiferan species richness and relative abundance in an area.


Acoustic monitoring Ambient noise recordings Crickets Focal animal sampling Hearing threshold India Katydids Species diversity Tropical forests