453. Notes on the vocalizations of Great Egret (Ardea alba)

Taxonomy has been discussed in the literature over the years, with a species-level split of modesta being recommended by some authorities (Kushlan & Hancock 2005, Christidis & Boles 2008, IOC 1.6– 2.7), but following a summary paper (Pratt 2011) most commentators have again elected in favour of caution and have treated the four taxa as a single species. Pratt in fact concluded that existing evidence could support only two reasonable options (either lump all four taxa or elevate egretta to species rank) but that future genetic studies might result in the acceptance of more biological species. While taxonomic discussion has focused mainly on morphology, courtship behaviour and genetic data, voice has apparently never been included in the discussion. This is hardly surprising, as vocabulary in large herons is rather limited and calls of most species sound superficially similar, thus are seemingly of little use for taxonomic analysis. Nevertheless, in any given locality, sympatric herons can often be distinguished by call. It seems worthwhile therefore to check for vocal differences among the allopatric taxa of Great Egret.