Little Egret - presumably?

["Trevor Ford" <>]

Last week I came across a group of three Little Egrets feeding in tidal
shallows.  Whilst two were the standard issue with black bills and black
legs, the other was markedly different.  It had a bill that was completely
yellow from the base to about halfway along (not just the lower mandible)
and then jet black to the tip.  It also had greenish-grey legs with slightly
yellower feet.  No plumes were obvious on this bird but could be seen on the
napes of the other two.  The size, structure and jizz of all three birds was
the same.  So what was I looking at?  The field guides say that the bill on
an Australian Little Egret is always black - and my 'Herons Handbook'
doesn't offer any clues.  Are there variations on the Little Egret theme
that I don't know about.  (Call me anything you want - within reason - but
please don't tell me I was looking at a Reef Egret!)

Cheers - Trevor.