Herons

Today's Facebook feed brought me this delightful photo, by Alex Shkolnik, of five little egrets (Egretta garzetta), a black-crowned night heron (Nycticorax nycticorax), and a purple heron (Ardea purpurea), at a fish pond in northern Israel. Poised for a quick snack.

The comments included a debate over the Egretta species, one person insisting that "here" we call them snowy egrets. Turns out, the heron world is larger than that commenter knows, because: those are little egrets, not snowies. They look similar, but they are different species. (Snowy egrets are E. thula.) The identifying mark, besides size—littles are a little bigger than snowies—is their "lore": the patch of skin separating beak and eye. Snowies' are orange, red, or bright yellow, depending on the breeding season, while littles' are green, dull yellow, or gray. Easy!

But all that got me wondering how many types of herons there are overall. Turns out, 64—and these include herons, egrets, and bitterns. They are in the family Ardeidae, with three subfamilies.

According to Wikipedia, "Although herons resemble birds in some other families, such as the storks, ibises, spoonbills, and cranes, they differ from these in flying with their necks retracted, not outstretched. They are also one of the bird groups that have powder down. Some members of this group nest colonially in trees, while others, notably the bitterns, use reed beds. A group of them is called a 'siege.'"

One heron that formerly made up its own lonely monotypic family, but now has been rudely shoved into the large and diverse Ardeidae, like it or not, is the boat-billed heron (Cochlearius cochlearius), found in mangrove swamps of Mexico south to Peru and Brazil.

The two (out of 18) main genera within the Ardeidae family are Ardea and Egretta: the herons and egrets, making up a third or so of the total species. There are also whistling, capped, pond, green-backed, night, and tiger herons, not to mention the bitterns. Here are some exemplars. They are beautiful birds.

Green heron, Butorides virescens.
Photo by Barbara Houston

The largest heron, Ardea goliath, lives in
sub-Saharan Africa. It stands 4 to 5 feet tall,
with a wingspan of 6 to 7.5 feet, and
weighs 9 to 11 pounds.
Photo by Guy Poisson.

One of the smallest herons is the least bittern
(Ixobrychus exilis), 11 to 14 inches in length and
weighing a mere 2 to 3 ounces.
Photo by Jim McCormac.

Bare-throated tiger heron (Tigrisoma mexicanum),
found from Mexico to northern Colombia.
Photo by Linda Murdock.

Capped heron (Pilherodius pileatus),
inhabiting rainforest from central
Panama to southern Brazil.
Photo by Andreas Trepte

Great egrets (Ardea alba).
Photo by Fraida Gutovich

And finally, here is a black heron (Egretta ardesiaca) using its "wing umbrella" to hunt, at Rondebult Bird Sanctuary, Johannesburg, South Africa:

You may have noticed that the "black heron" is an Egretta, while the "great egret" is an Ardea. The common names are a bit like the difference between prawns and shrimps*: that is, common usage. "Egrets" are, basically, white herons, while "herons" are anything else. Unless they're a bittern. But let's not complicate matters.

Where I live, we have great egrets, great blue herons, green herons, snowy egrets, cattle egrets, black-crowned night herons, and American bitterns. And maybe others as well, though I haven't seen them. The great egrets and great blue herons nest in trees near Elkhorn Slough and Pt. Lobos. It's always fun to watch them squabble and carry on, up there on high.

*For the record, prawns are large, shrimps are small—in common usage. But scientifically, shrimps brood eggs, whereas prawns release them into the water--and then there are various anatomical differences. The Monterey Bay spot prawns that I love to eat? Shrimps.