Life On Stilts — March - April 1996

by Janice Welsh

great egret

What kind of bird has a neck like a snake and legs like stilts? A heron does. Herons are leggy, mostly long-necked wading birds.

Long legs allow herons to wade into lakes and ponds in search of food. Long, thin toes help them walk on the soft, mucky lake bottom without sinking or getting stuck.

Six species of herons live in Minnesota during spring and summer: great blue heron, black-crowned night heron, green heron, great egret, American bittern, and least bittern.

Heron nests are easy to spot in early spring before the trees leaf out. Three great rookeries are Kabekona rookery southwest of LaPorte on Minnesota 64, Madden's rookery north of Brainerd on County 77, and Pigeon Lake rookery south of Dassel on Minnesota 15.

Rookeries

During breeding season, most herons gather in large colonies to nest. This nesting place is called a rookery.

Herons use dry twigs to build their sloppy nests. Often, they put the twigs so far apart that you can look up through the bottom of the nest and see the eggs!

A rookery might have a few nests or as many as 200 nests. Different species build their nests at different heights, from ground level to 160 feet in the air.

Herons nest in big groups for a good reason - a lot more eyes watching out for predators. By building their nesting colonies near marshes, lakes, and streams, often on islands, the birds can stay away from predators such as snakes, raccoons, and foxes. Crows still can raid the nests.

Because the parent birds might leave their nests if people bother them, some rookeries on state land are not open to people from May 15 through July 15.

great blue heron

Great Blue Heron

The largest of North America's 12 heron species, the great blue heron stands almost 4 feet tall.

This adaptable bird lives throughout Minnesota. The southern and central parts of the state have the largest rookeries. Great blue herons often choose the highest treetops for their nests.

Male and female great blue herons show off to each other during courtship. They flap their wings and dance in circles. They nibble at each other's feathers. The males strut and peck at each other, swinging their bills like swords.

Though great blue herons sometimes eat walleyes, northerns, and other game fish, they feed mostly on small nongame fish, aquatic insects, crayfish, frogs, and small mammals such as mice.

During nesting season, both parent birds incubate the eggs and feed the chicks. The parents fly off in search of food, then return and regurgitate food for the chicks. After they have raised their families, great blue herons fly south to spend the winter in wetlands and coastal waters of the southern United States and Central America. Except during the breeding season, they live alone.

Often herons swallow their food alive. Sometimes a heron catches a fish and flips it into the air so it goes down head first. Sometimes a heron spears and shakes the fish to kill it and make it easier to eat.

black-crowned night heron

Black-Crowned Night Heron

This medium-sized heron stands about 2 feet tall. Its legs are shorter than those of other herons.

In the spring black-crowned night herons live in rookeries with egrets and great blue herons. This is the bird that nests 160 feet high in fir trees in Oregon.

Black-crowned night herons make a loud quock sound when disturbed. They are most often heard at dusk and dawn.

green heron

Green Heron

Unlike most water birds, green herons use bait to catch their food. They present worms and twigs to lure small fish closer to the shoreline.

When startled, green herons fly away quickly. They make an alarm call that sounds like skeow, and leave a small white trail of bird droppings, which has earned the green heron the nickname "chalk line."

Green herons nest in small trees and bushes near water. The male selects the nesting place and starts building. Later he brings sticks to the female, which finishes the nest. Sometimes green herons remodel an old egret or black-crowned night heron nest. Both parents incubate the eggs.

great egret

Great Egret

Egrets are herons too. The name egret comes from the long back feathers called aigrettes, which appear during breeding season.

Egrets nest in rookeries. Parents feed their nestlings about four meals a day. Older, stronger baby egrets will kill their smaller siblings if they do not have enough food to go around. Adults will not interfere in the youngsters' battles.

In the early 1900s, the feather trade almost wiped out egrets in many places around the world. Most aigrettes ended up on hats. Hunters sold the feathers for $32 an ounce - two times the price of gold at that time. Fortunately, fashion trends changed, and people passed laws to protect the birds. The Audubon Society formed to save egrets and other wading birds. It took more than 30 years for egrets to make a comeback.

American bittern

American Bittern

In tall reeds a 2-foot-tall bittern waits for its prey. At dawn and dusk it dines on insects, frogs, crayfish, and small fish.

If you walked nearby, you probably would not see the bittern. Its body blends with the reeds. It even sways with the breeze. Pointed up at the sky, its beak looks like a reed.

The bittern belches out a weird song. Imagine a quartet of singers loudly singing the low notes - oong-ka' choonk. That's what a bittern sounds like. The booming call has earned it the names "thunder-pumper" and "bog bull."

The bittern calls to warn rival males and to attract a female mate. To threaten a rival and court a mate, the male also shows a ruffle of white feathers on its back.

The female handles all of the chores of raising the family, including building the nest.

Janice Welsh, author of this article, runs Project WILD, a DNR program for schools.

A complete copy of the article can be found in the March-April 1996 issue of Minnesota Conservation Volunteer, available at Minnesota public libraries.