WW1 recruiting poster (ANZAC)

[Kraut]

A question with historic background, mostly aimed at those board users from Australia and New Zealand.

I am currently reading a well-illustrated book about WW1. This book features a range of propaganda and recruiting posters from several nations. The recruiting posters from Australia catched my special interest:

On most recruiting posters from Australia (and NZ) an ANZAC soldier is pictured, shouting out "Coo-eee..." followed by sentences like "...when do YOU join us in Gallipoli?" or "...we need YOU over here!"

What does "Coo-eee..." mean? It must have some special Australian meaning, but my English dictionary does not know anything about it

[Norge]

Wikipedia to the rescue!
http://en.wikipedia.org/wiki/Cooee

[Kraut]

Now that was quick help!

Thank you very much, Norge.

[EireEmerald]