Some Vocal Characteristics and Call Variation in the Australian Corvids

Abstract

Some vocal characteristics and call variation in the Australian crows and ravens were studied by sonagraphic analysis of tape-recorded calls. The species grouped according to mean maximum emphasised frequency (Australian Raven Corvus coronoides, Forest Raven C. tasmanicus and Torresian Crow C. orru with lower-frequency calls, versus Little Raven C. mellori and Little Crow C. bennetti with higher-frequency calls). The Australian Raven had significantly longer syllables than the other species, but there were no significant interspecific differences in intersyllable length. Calls of Southern C.t. tasmanicus and Northern Forest Ravens C.t. boreus did not differ significantly in any measured character, except for normalised syllable length (phrases with the long terminal note excluded). Northern Forest Ravens had longer normalised syllables than Tasmanian birds; Victorian birds were intermediate. No evidence was found for dialects or regional variation within Tasmania, and calls from the mainland clustered with those from Tasmania.