Crafty, small green heron uses bait to catch its unsuspecting food

What's Barrington's village bird? The great blue heron. What's the symbol of the National Audubon Society? The great egret.

That's all fine and dandy, but who's going to stick up for the smaller herons? I am. In particular, I would like to present the green heron (Butorides virescens).

A heron review

Herons and egrets belong to the same group of wading birds. Herons have broad wings, short tails, and long legs. They are often seen standing or slowly stalking along a shoreline. The birds are looking for aquatic meals such as frogs, fish, and crayfish.

Most herons are colonial nesters. Their large nests are clustered together in tall, dead trees near water. In flight, herons fold their necks in an 'S' shape. Cranes, by comparison, fly with their necks outstretched.

Green heron feather specs

At 14 inches in length, the green heron is our area's smallest heron. This bird used to be known as the little green heron. Folks joked that this bird got the name because it had very little green on it. To wit, it has a dark back with some blue feathers, mahogany-black beak, yellow or orange eyes and legs, chestnut sides and neck, all topped off with a shaggy green-black cap.

At a distance, a flying green heron might be confused with a crow. Compared to a crow, the heron's arched wings beat at a slower rate. Also, the raucous "kyow" call of a startled green heron is nothing like a crow's caw.

The surprised heron adds an exclamation point of white feces as it flies off. This habit has earned the species regional nicknames of shite-Polk and chalk-line.

Habitat and habits

Ornithologist A.J. Meyerriecks describes green heron habitat best, writing there is "scarcely a stream, swamp, or shoreline where it may not be found .…" This includes thickets near fresh or saltwater. Stillman Nature Center's pond-side surroundings are Exhibit A for green heron habitat.

Unlike its bigger relatives, green herons do not nest in large colonies. They prefer to nest as isolated pairs or in small groups. We don't know where their nest is here at Stillman, but there has to be one somewhere on our 80 acres.

Because the green heron is smaller than the "great herons," it is much more likely to use a floating log or low branch as a hunting perch. With that in mind, we gave these small herons a couple of new shoreline hunting options.

Reduce, reuse, recycle

With the help of volunteer John Gibbons, we took two 6-inch-by-6-inch wooden sign posts that had rotted away at the bottom from near Penny Road to the pond.

After they were put in the water and attached to the lake's edge, I watched to see what types of wildlife would use them. It did not take long for frogs and turtles to bask on the flat surfaces we provided. By far, though, the animals that have used these rectangular logs the most were hungry green herons.

Green heron diet

What do these herons eat? I think the better question is what don't they eat? Let's start at the top of their bill of fare: green herons eat fresh and saltwater fish. Their menu includes sunfish, catfish, carp, perch, minnows, pickerel, goldfish, and eels. Other vertebrate prey are fish, frogs, toads, tadpoles, snakes, newts, and rodents.

As for invertebrates, green herons will gobble down crayfish, crabs, snails, spiders, leeches, earthworms, plus adult and larval dragonflies, damselflies, diving beetles, water bugs, crickets, grasshoppers, and katydids. They routinely forage in water that is less than four inches deep.

Luring their prey

Green herons use various feeding techniques. The most common behavior is to stand in a crouched posture, body horizontal, head and neck drawn in, closely examining the water.

They will hold this position for quite some time. When prey is within reach, the bird will dart its head out and down, often with a body lunge.

As the photos illustrate, the herons' heavy stabbing beak is an excellent tool for catching dinner, but that's not why green herons are known as tool-users. What kind of tool does a green heron use?

A fishing pole? No. But what do you attach at the end of the fishing line? Bait. Green herons form bait to attract fish to the water's surface.

In particular, green herons have been recorded bait-fishing with broken sticks, feathers, insects, and even crusts of bread. In one instance, a green heron drove off another bird that was going for the bread.

Is this innate or learned behavior? I will confidently answer that question, "Yes." Arguments can be made for both types of behavior. Examples of immature green herons bait-fishing suggest the hunting practice is deeply ingrained. To be fair, other herons also bait-fish, but not to the extent of the clever green heron.

Confusing names

The North American green heron can be found across the eastern half of the country, plus a strip along the West Coast. Our small heron is part of a matrix of green heron populations and subspecies that range over subtropical and tropical regions This small genus of herons is periodically revised, reclassified and renamed.

Such reorganization is a taxonomic playground for splitters and lumpers. Splitters, you see, like to put species into precise, detailed categories. Lumpers use broader definitions that allow more variety to be filed under the same species name.

I'll leave the splitting and lumping to the green heron. The way I see it, the heron puts out a lump of bait and then splits the prey that takes the bait with its beak. Any questions?

• Mark Spreyer is the executive director of the Stillman Nature Center in Barrington. Email him at stillmangho@gmail.com.