Great White Heron – Mangrove Portraits (and an issue of taxonomy)

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Audubon left Charleston aboard the Cutter Marion on April 19, 1832. The vessel passed the Cape Florida Light, and reached Indian Key on April 24th, where it remained for a week. There Audubon became acquainted with James Egan, a Bahamian.  Audubon hired Eagan as a guide and with his help explored rookeries through out the Florida Bay and surrounds. When Audubon landed on Indian Key, it was Egan who introduced Audubon to the majestic white wading bird that today is largely considered a color morph of the Great Blue Heron.  However, in 1832, this white bird was different from any Audubon had previously seen and he was understandably delighted at this new discovery. Audubon is credited with the naming of this new bird, Ardea occidentalis, Aud, 1835. You will see in the excerpts below from the Ornithological Biographies, that Audubon described differences and similarities between the Great White Heron and the Great Blue Heron in their behaviours. So he was consciously comparing these two large and equally distinctive herons:

“The Great White Heron is a constant resident on the Florida Keys, where it is found more abundant during the breeding season than anywhere else. They rarely go as far eastward as CapeFlorida, and are not seen on the Tortugas, probably because these islands are destitute of mangroves. They begin to pair early in March, but many do not lay their eggs until the middle of April. Their courtships were represented to me as similar to those of the Great Blue Heron.  Their nests are at times met with at considerable distances from each other, and although many are found on the same keys, they are placed farther apart than those of the species just mentioned. They are seldom more than a few feet above high water-mark, which in the Floridas is so low, that they look as if only a yard or two above the roots of the trees.” “These Herons are sedate, quiet, and perhaps even less animated than the A. Herodias. They walk majestically, with firmness and great elegance. Unlike the species just named, they flock at their feeding grounds, sometimes a hundred or more being seen together; and what is still more remarkable is, that they betake themselves to the mud-flats or sand-bars at a distance from the keys on which they roost and breed. “

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While it is generally accepted that this Florida Keys bird is a color morph of the Great Blue Heron, this opinion is not unanimous. Some scholars may waiver on allowing the bird its own species status; but, there are many who see that it certainly deserves sub-specie status. I tend to be one who feels that the Great White Heron residents of the mangrove communities of the Florida Keys are distinctive in more than just color from the Great Blue Heron. For me there are physical differences in shape, plumage and bill size (from observation not measurement).  So I feel that Ardea herodias occidentalis is appropriate naming and honors a sub-specie status for this unique and remarkable bird. It respectfully retains the specie name (occidentalis) given by Audubon in 1832. I have read there exists a white morph of the Great Blues in Cuba, Jamaica, the Yucatan, and off Venezuela which are smaller than the Keys birds and quite uncommon.  So between plumage length, size of bird and other considerations, there is a case for sub-specie status.  There is an excellent, thought provoking discussion of this issue at Sibley Guides. They have posted a really interesting discussion about the intermediate species, the Wurdemann’s Heron, which is found mainly with the Great Whites. My understanding has always been that the Great Blue Heron when it mates with a Great White produces the Wurdemann’s Heron typically exhibiting a white head but otherwise dark body. If they breed together, that would support the same species nomenclature. However, if (as Sibley’s article suggests) the dark birds in the keys are not like the mainland Great Blues, then the argument gets more interesting. The idea that the Wurdemann’s may actually be a color morph of the Great White Heron which would make the Great White Heron a dimorphic bird subspecies to the Great Blue Heron is a true turnabout in thinking.   My own observations in Flamingo and Key West where you will see the intermediate birds together with the Great White Herons is that they seem more like the Great White in shape and size than the Great Blue. And, the colors are variant, not just a pure white head and Blue Heron-like body but the quite a few variations which I thought of as the result of White-Blue breeding, then offspring Wurdemann’s breeding with either White or Blue and so on.  Last year there was a Wurdemann’s-like Heron in a nest with a Great Blue at Wakodahatchee Wetlands, which was most unusual so far north. And, I still wonder about that. It looked like a Great blue in size and shape but with a white head, white head plumes and white under belly feathers.

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This is the first Wurdemann’s Heron I ever saw and at Flamingo one sweltering August.  At first I thought it was a Great Blue, but then it looked dazzling in the light and I realized the colorations were different. It has a mostly white head with some dark speckles and unusual lightness in the body feather colorations. The under body feathers are white and not black like a Great Blue.

This Great Blue Heron and its Wurdemann’s or Wurdemann’s – like mate at Wakodahatchee in the Spring of 2012. Clearly it is a variant with its whiter head with speckled dark, white instead of black plumes, and white underbelly instead of black. I found it most unusual to find a variant this far north. Wurdemann’s can only occur where there are Great Whites (and Great Blues or so I thought).

Wurdemann’s with chick…the parent clearly showing the pure white head plumes.

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It is worth noting that the Wurdemann’s heron or Ardea wurdemanni was named for Gustavus Wurdemann who first collected this color variant heron so similar to the Great Blue Heron. Wurdemann was employed by the US Coast Survey in 1837 and worked as a tidal and meterological observer in Florida and the Gulf of Mexico. In his spare time he collected objects of natural history and was stationed at places along the coast rarely visited by other naturalists and suceeded in acquiring a few species new to science. The Smithsonian Institution retains his collections. His most well known discovery was the Wurdemann’s Heron which bears his name. In researching this information I learned that Wurdemann died very young on Sept 29, 1859 in New Jersey at the age of 41.

As Wurdemann was active in the 1850’s with collections for the Smithsonian and Audubon died in 1851, I don’t believe they ever crossed paths.  It seems they both were in the Florida Bay area in the 1830’s but at opposite ends of the decade. Without further research, I don’t believe that Audubon was ever aware of an intermediate bird between The Great White Heron and The Great Blue Heron. Should I learn differently, I will update this post.

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I actually did not mean to get into the taxonomic argument with this post, but I suppose it is inevitable as it is something I always have in mind when photographing Great White Herons. I remember at times my college zoology professor telling our class that when it comes to taxonomy there are lumpers and splitters.  Could be a personality trait of some sort revealing whether you tend to admire or find remarkable the differences between things or the similarities. But, there should be good reason to enter a new specie name into the taxonomic kingdom.

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The portraits displayed at the top and below are very typical Florida Keys Great White Herons in a mangrove setting similar to that which Audubon observed in his time. These were taken on Key Largo in the Pennecamp area in the month of June. I believe these to be young adult specimens.

A black and white treatment of a Great White Heron in its mangrove habitat.  I love the tangled artistry of the branches and root systems of the Red mangroves we enjoy along the waterways of Florida Bay and the Keys.

A color image for comparison with the black and white treatment. While the white feathers certainly stand out, the legs of the bird blend in color with the roots and branches of the mangroves. Creatures always seem to fit their environment.

Audubon’s Great White Heron was painted near Key West, after a night hunt with James Egan.  Key West is depicted in the background.

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The art and science of naming has always been a fascinating subject for me.  It seems to me a great occupation trying to define and quantify such glorious diversity as we are graced with.  Just as you can only appreciate and value something if you experience it, I think the close observation necessary for such definition and the award of a name only increases a sense of wonder about the way things work.

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As Ever,

Judy

~ by Judy on October 23, 2013.