The prehistoric-looking Great Blue Heron is one of the largest and most conspicuous of Florida’s wading waterbirds. Although it is often mistaken for a crane, it is actually a member of the heron family.
There are five subspecies of Great Blue Heron in North America. Most are of similar appearance, being very tall (up to 4.5 feet), greyish slate-blue in color, with long necks, long wading legs, pointed bills, and whitish stripes on the head. The most common and widespread is Ardea herodias herodias, which is found for at least part of the year from Mexico all the way to Canada. In the northern US it migrates south for the winter. On the Pacific Coast, from Alaska to California, is the subspeciesArdea herodias fannini, which looks similar. The population ranging from Kansas to the Gulf of Mexico and down into Florida is recognized as the subspecies Ardea herodias wardi. Like thefannini subspecies, the wardi tend to be permanent residents and do not usually migrate. The isolated Galapagos Islands, off the coast of South America, have their own subspecies Ardea herodias cognata. The most distinctive subspecies is Ardea herodias occidentalis, which largely replaces the “normal” Herons in southern Florida, the Keys, and the Caribbean. It is starkly different in appearance from all the others, being almost pure white, and is also, on average, slightly larger. For many years, argument has swirled amongst biologists as to whether the “Great White Heron” is just a color morph of the wardisubspecies, a distinct subspecies of its own, or perhaps even an entirely separate species. Since they can interbreed, and intermediates (gray birds with white heads) can be found where the two groups overlap, most authorities class them as a subspecies.
In Europe the Great Blue Heron is replaced by the Grey Heron,Ardea cinerea, which is very similar in appearance and habits. In South America the species is Ardea cocoi.
Like all of our herons, the Great Blue is a wader that is never found far from water, both salt and fresh. It spends most of its time patiently stalking in the shallows, where it feeds opportunistically on everything from small fish to shrimp to frogs to baby alligators. It uses its long neck and sharp beak to nab prey. Herons have been observed standing in the water with their wings held out to create a patch of shade to attract fish. In the Pacific Northwest, the fannini subspecies preys on voles and mice along riverbanks. I have sometimes seen Great Blues in Florida pick Anole lizards off bushes.
Breeding takes place from November to March. Great Blues will sometimes nest together with other waterbirds like egrets and anhingas, in large rookeries, but also will form large single-species breeding colonies with over 100 nests. The males choose a nesting site and attract females through a display that involves a lot of neck-stretching and bill-clacking. The pair then builds a nest of sticks, which may be on the ground but is usually up in a tree. The male often re-uses a nest next from year to year, but the females usually mate with a different male each season.
The female lays three or four pale blue eggs, usually two days apart, which each hatch after about 28 days. Both parents take turns feeding the chicks. The young birds can fly in about two months, and leave on their own at three months. In southern Florida each pair can produce two broods per year. Estimates put the Florida population of Great Blue Herons at over 10,000. It is classed as a “Species of Least Concern”.