[Marco Island, Estero, and Fort Myers, FL. Aug/Sep 2013]
The status of the Great White Heron at various times has been that of full species, subspecies or just a color morph of the Great Blue Heron.
This excellent article by David Sibley explores some of the aspects in this debate with a likely conclusion that an acceptable determination could very well be that of subspecies status.
Superficially, the Great White looks a lot like a Great Egret -- a large, white heron with a yellow bill.
Here the two herons' headshots are seen side by side; and, some differences become clearer.
The Great Egret is on the left and has a yellower, smaller bill. The Great White has bluish lores and a straighter upper mandible. The plumage texture of the Great Egret is finer while the Great White looks comparatively gruffy.
But is the Great White just a color morph of the Great Blue (shown above)? Like a white tiger, is the Great White merely a pigment variant? (neither is albino since pigment is clearly visible).
In this comparison (disregarding color), the Great White appears bigger-billed; and, the Great Blue has an obvious head plume which the Great White lacks (indeed, it lacks the long plumes on the lower neck as well). Finally, the forehead of the Great Blue meets the upper mandible farther down the bill, giving the slope of the forehead a more rounded look.
Another distinctive feature is leg color; Great Egret's are black while Great White's are a pale yellow.
Other waders observed were much more readily identifiable:
A Reddish Egret (seen at Little Estero CWA), dancing for fish.
Reddish Egret is our most conspicuous canopy feeder and also occurs in a white morph -- a status that is not disputed.
Changing venues to Bunche Beach Preserve, another couple of wader species were found -- two smaller herons: Snowy Egret (above) and Little Blue Heron (below).
Taking a break from herons, here's a species that always qualifies as every photographer's eye candy, the Roseate Spoonbill:
Finally, some shorebirds:
A Piping Plover extracting a worm.
The Avian world has 10,000 species -- approximately. The exact number is somewhat in flux as species get split or lumped. These developments are driven by research, science and dedicated field work that all add to the wonder of birding as a pursuit. And, the enigmatic status of the Great White Heron is reflective of this dynamism.