This interesting heron has been seen for several consecutive summers
at Canonsburg Lake, Washington County, and after long study is now considered by many to likely be a hybrid between a Great
Blue Heron and a Great Egret. It was first noticed in 2002 and was still present during the summer of 2007. I personally first
saw and photographed it in April 2004; the long-range digiscoped photos I obtained that day are below. (As an aside, I have
long wanted to get better pictures of this bird and have tried at least a dozen times over the years, but bad luck haunts
my every attempt. Maybe 2008 will be the year it finally happens...)
The bird superficially resembles a Wurdemann's heron--the intergrade morph
between Great Blue Heron and "Great White" Heron that has a white head and neck. It might also simply be an unusual leucistic
Great Blue Heron. However, there are several structural characters that are inconsistent with pure Great Blue Herons of any
color morph and which point to Great Egret lineage:
1. In spring when the bird is in high breeding plumage, it lacks the occipital plumes of a
Great Blue Heron, as does Great Egret
2. The bird has an elongated, thin neck, as does Great Egret
3. The bird lacks the shagginess at the base of the neck typical of a Great Blue; instead the base of
the neck is neat as a Great Egret's is
4. The bird's bill is not seem massive enough nor does it have a straight enough culmen, more like a
Great Egret than a Great Blue
5. Though not visible in the photos, the bird's behavior seems more egret-like than heron-like to me.
Great Blues plod around the marshes very deliberately when hunting. This bird was much lighter-footed,
hopping around the lake as it fished, which gave a more egret-like impression.
Note that all of the characters I mention above relate to structure, not to plumage, which is important. Indeed,
the plumage is a fair representation of what a putative Great Blue Heron x Great Egret might look like, but taken alone, plumage
really is not a singularly reliable indicator of genetics in this case. A number of genetic anomalies could produce
an odd plumage in an otherwise normal Great Blue Heron.
But when this bird's hybrid-like plumage is taken in conjunction with the more telling structural anomalies,
the hybrid theory, as unlikely as it seems, is to me a more accurate explanation of the evidence at hand than the theory that
several genetic anomalies give this "pure" Great Blue heron the partial appearance and structure of a Great Egret.
Please understand that I do not claim to know that this bird is a hybrid; I don't know what it is, but I think hybrid
is the best explanation based on the information available. At the same time, I do recognize and concede the unlikelihood
and downright absurdity of a hybrid between a 2-pound egret and a 5-pound heron, especially in a geographic area where Great
Egrets are not known to breed. Yet here we are, with a bird that, to me, shows definitive characters of both species. Maybe
someday someone can just go get a feather from the bird and put the question to rest once and for all....
