Birds patiently wait for a frog meal

Four species of frogs and one toad species live in the swampy marsh behind our home. They are bird food, the kind that provides a show for a watchful birder.

It's easiest to identify these creatures by their voice, each distinct: leopard frog, wood frog, chorus frog, a species of gray tree frog, and American toad.

I've seen the leopard and wood frogs and the toad. Leopard frogs fell into a window well until I covered it. Wood frogs are dangerously (for them) active during breeding season. They scurry after one another in shallow water, leaving little waves of disturbance.

The toads, almost always juveniles or whatever it is you call a not-fully grown toad, can be found in our lawn. When I'm mowing, I have said "Ohhhh" more than once.

Chorus and tree frogs go unseen, very alert and well camouflaged if you try to pin a voice to a body. The other day, though, a tree frog fell out when we opened our patio umbrella. They hide during the day.

Birds, on the other hand, don't need window wells or lawn mowers. I've watched a broad-winged hawk successfully hunt frogs in our yard, launching a strike from a branch overhanging the marsh. Barred owls eat frogs in the coffee darkness of the wee hours. I've never seen that.

Champion among the frog hunters for me is the green heron, because it hunts most frequently and is easy to see. The heron starts its hunt with a frog-filled pond, extreme patience and good eyesight. And then it follows this technique: Wait. And wait and wait. Stab. Swallow.

I wish for fish because green herons are known to fish with a lure, and I'd like to see that.

Green herons will stand in the water or at its edge, using a leaf as bait. The bird drops the leaf into the water and waits for a fish to investigate. Stab. Swallow. If the water is moving, the heron will in effect cast upstream, then follow the float with a long neck and sharp tool.

If no fish responds, the heron simply does it again. It's the same patience that herons display when waiting for frogs. In our duckweed-covered pond the bird would unerringly strike at the slightest protrusion of frog head, showing off its good eyesight and excellent reaction time.

One day a heron caught a leopard frog. They can be 4 or 5 inches long, and weigh 2 ounces. The problem here, as I saw it, was not catching as much as swallowing. The heron weighs about half a pound, the weight of only four frogs.

The first thing the heron did after the catch was repeatedly slam the frog against a log until the amphibian was dead, and possibly just a green bag of broken bones. The bird does this with fish, as well.

Two frog legs didn't go down. They dangled. The heron stood motionless. Perhaps it was thinking about Plan B. Suddenly, it coughed up the frog and started over.

It reworked the frog into position, looked to the sky and swallowed again. This time the entire frog disappeared. The bird flew away. Show over.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com. Join his conversation about birds at www.startribune.com/wingnut.