Dive Dry with Dr. Bill

#469: The Green... Heron

I don't understand the fascination with comic book heroes like Superman, Batman or the Green... Hornet. Heck, the topic of this week's column could probably take on either of the first two when it comes to flight, and would eat the last one as a spicy appetizer! I'm talking 'bout a bird found from Florida where I am now to California where I'll be back soon, and from Maine and Washington state as far south as northern South America. Why, a few have strayed all the way to England, France and even Hawaii!

The green heron is known scientifically as Butorides virescens. However, there does appear to be some confusion as to whether it is a unique species or part of a complex of small herons including the striated heron and the Galapagos heron. When lumped together into a single species, they are collectively known as the green-backed heron. Determining the precise answer to this question is well beyond the pay grade of a lowly kelp forest ecologist and undoubtedly requires a DNA test! Green heron populations that reside in warmer regions such as southern California, Baja, Florida and the Caribbean are generally resident year-round and do not migrate. Those from the northern end of this species' distribution do migrate and these populations often possess somewhat longer wings.

The green heron lacks the obvious, very long neck of the great blue heron, but can extend its dark, pointed bill a fair distance when feeding. It is a relatively small (up to 18") wading bird, dark in color with long yellow legs. The cap of the head is greenish-black and appears glossy, the back and wings are dark grey or black in color becoming greenish or bluish. The chestnut neck has a white line down the front and is usually held close to the body. Females may be smaller and have more subdued coloration, especially during the breeding season.Young birds have a brownish neck and chest which is striped and their brown back often has buff colored spots.

Individuals may be hard to detect while they stand motionless waiting for prey to pass a little too close. Although usually found near freshwater swamps, marshes, lakes and streams they usually winter in coastal areas, favoring mangrove habitats. The ones I filmed for today's column were both observed near the mangroves that line the yacht basin below Mom's Florida condo.

The Cornell University Lab of Ornithology states that the green heron is one of the few birds that has evolved the ability to use tools. We know of birds that use thorns to extract insects from beneath the bark of trees. This heron has developed a very interesting way of catching fish. It drops "bait" in the form of bread crusts, insects, worms or even twigs and feathers on the surface of the water and then extends its neck and body to grab the curious fish that arrive to inspect the bait.

The green heron is most noticeable at dusk and dawn since it is more a nocturnally than diurnally active species. They often hide during the day unless they need to feed due to hunger or when raising their chicks. Their diet consists primary of small fish, frogs, aquatic invertebrates such as crabs and even insects (although I'm not really sure about green hornets). They prefer to feed alone and do not tolerate the presence of other birds, including their own species. The individual I observed feeding was perched on the stern line of a small boat near Mom's home, looking like the Wallenda of the Waves. It would observe the water below it keenly and lean towards the surface, darting down and extending its neck to catch a tasty morsel... or a mouthful of water!

When mating these birds are "seasonally monogamous," remaining paired up for the entire breeding season. Birds in the tropics may breed twice a year. Males use exaggerated courtship displays to attract the female to the nest site chosen by him. They squawk and fly in front of the female with the feathers on their head and neck all puffed out. Nests may be on the ground, in shrubs or in trees which are favored. Between two and six pale green eggs are laid several days apart. The clutch is incubated by both parents and the young may begin to leave the nest in just over two weeks. When they are four to five weeks old they are able to fend for themselves. I know a lot of parents my age and younger who wish their kids would take a lesson from the green heron. Fortunately, I am not one of them!

© 2011 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Green heron perched on railing and another individual fishing from the stern line of a small boat.

This document maintained by Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia