Ecology and taxonomy-driven deviations in the frog call-body size relationship across the diverse Australian frog fauna

Abstract

Relationships between some properties of frog calls and body size are widely recognized. However, generality across call components and diverse faunas, and sources of deviation, remain poorly tested. Using 116 east Australian frog species, we tested the relationship between three call traits and body size, and the effects of taxonomic family and calling habitat. Call dominant frequency (DF) has a highly significant negative relationship with size, whereas call duration and pulse rate do not. Frog families show the same slope of relationship between DF and size, but hylids call at significantly higher frequency relative to size. Within hylids, stream breeders call at significantly lower DF than pool breeders of comparable size - below the DF of stream noise in typical breeding habitat - a shift likely to enhance signal detection against background environmental noise. This contrasts with all previous observations from other regions that frogs call at high (even ultrasonic) frequency to avoid masking by stream noise.