Be that as it may on the Gray heron, but I've seen one and it wasn't blue, it wasn't white and it was pointed out by a 37 year veteran guide as a Gray...sometimes the books are wrong...or maybe not.
The books aren't wrong in terms of expected native species, so my original list of North American herons is correct.
Vagrants from Europe and Asia do wander to North America on occasion (and would generate a "rare bird alert" amongst birders) and there have been reports of Gray Herons in North America (see the Gray Heron page
at Animal Diversity Web), but an Internet search turns up only one confirmed North American report
(in Newfoundland, Canada).
Remember that Gray Herons (Ardea cinerea
) and Great Blue Herons (Ardea herodias
) are similar in appearance (the Great Blue is actually more gray than blue). So while it's remotely possible you saw a Gray Heron in the Okefenokee Swamp, it's more likely that your veteran swamp guide was wrong and that you both saw a normal American (gray-colored) Great Blue Heron. Too bad you didn't get a photo