White Heron ... or Egret?

This mystery bird has been hanging around Gallon Jug for the past several weeks.  More specifically, along the Rio Bravo in Sylvester Village.  My neighbor Alan finally snapped photos of it, which took the ongoing local debate to a higher level.  At first glance, you'd assume it was a Great Egret (Casmerodius albus).  Common enough and readily seen in Gallon Jug during the winter months.  Something about the bill doesn't seem quite right though ... and it is using a slightly different habitat than we are accustomed to seeing for Great Egrets.  This bird seems to prefer shady areas along the river rather than the more open areas where we Great Egrets are more readily seen.

That habitat preference seems a bit more Great Blue Heron-ish (Ardea herodias) and it sort of has the Great Blue's form.  In fact, there is a rare white morph (=form) of the Great Blue Heron called Würdemann's Heron found only in the Caribbean .  And it's apparently not been recorded inland.  So is this Würdemann's Heron?  Our references were inconclusive.We consulted an upcoming ornithologist here in Belize, Roni Martinez, to get his opinion.  This is what he had to say:

"This bird is almost certainly a white morph Great Blue Heron ... note the white plume originating on the back of the crown and the gray, not black, legs. Great Egrets have black legs and do not have neck/crown plumes. Also, the bill is too thick for Great Egret."

 The Audubon Society Master Birding Guide  shows yellow legs and yellow bill as a field marks for the "Great White Heron" (aka Würdemann's Heron).  The photographed bird clearly has dark legs. The same reference says "yellow bill, black legs and feet" on the immature Great Egret.  That said, I do agree that the bill appears heavier.

  Roni replied:

"The legs on the Rio Bravo bird are definitely darker than normal but they are not black. The bill is right on for Great White, and the single head plume by itself eliminates Great Egret. The Sibley Guide has an illustration of a Great White Heron that approaches the bird in the photograph. Also check out the bill shape and color in the photo at http://www.oceanwanderers.com/NYGWHeron.html  

"I am no expert by any means on Great White Heron, so you should get a second opinion from someone with more experience with the species. Keep in mind that soft part colors (legs, bill, eyes) on Great White Heron are likely to be more variable than in a true species like Great Egret. Various intermediate stage between the Great White morph and the Great Blue morph are frequent (e.g., Wurdemann's Heron), and the Great Blue morph does have dark legs."

 So what do you think?  Opinions?  Guesses anyone?  Alan is going to try to get another photograph of it ... thanks Alan!