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Vertical stratification in an acoustically communicating ensiferan assemblage of a tropical evergreen forest in southern India

Published online by Cambridge University Press:  02 July 2007

Swati Diwakar
Affiliation:
Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
Rohini Balakrishnan
Affiliation:
Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India

Abstract

This study provides the first quantitative description of vertical stratification in calling heights of ensiferan species constituting most of the dry-season nocturnal acoustic community of an evergreen forest in Kudremukh National Park in south-west India. Calling heights of an average of 26 individuals of each of the 20 ensiferan species were measured and subjected to an analysis of variance to test for differences in mean calling height between species and a cluster analysis to check for the presence of discontinuous calling height layers. There were significant differences in mean calling heights between species. Calling heights of different gryllid and tettigoniid species ranged from the ground to the canopy. More gryllid than tettigoniid species occupied the ground and herb layer. Our study revealed vertical stratification of calling heights, with discrete layers corresponding to the canopy, understorey and the ground layer. These clusters emerged from the raw data of calling heights of individuals without a priori distinction of layers. We found no significant correlation between the calling heights of species and call features, including mean dominant frequency of narrow band calls, mean syllable rate and mean duty cycle.

Type
Research Article
Copyright
2007 Cambridge University Press

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