Class: Aves (Birds)
Height: largest—marabou stork Leptoptilos crumeniferus, 4.9 feet (152 centimeters); smallest—hammerkop Scopus umbretta 2 feet (60 centimeters)
Wingspan: longest—marabou stork, 10.5 feet (3.2 meters)
Weight: largest—marabou stork, 19.6 pounds (8.9 kilograms); smallest—hammerkop, 16.1 ounces (470 grams)
Life span: about 30 years, sometimes more than 40 years
Number of eggs laid: usually 2 to 5
Incubation: 25 to 35 days
Age of maturity: 1 to 4 years
Conservation Status: Oriental white stork Ciconia boyciana, Storm’s stork Ciconia stormi, and greater adjutant stork Leptoptilos dubius are endangered; most stork species are vulnerable due to loss of habitat, especially wetlands.
marabou stork’s bill grows all its life and can be 13.6
inches (34.6 centimeters) long. The large, heavy bill is a formidable
weapon against other scavengers, even hyenas and jackals.
Storks are usually quiet, but they can make a variety of sounds that range from hissing, honking, and croaking to squealing, mooing, and whistling.
Abdim’s storks Ciconia abdimii and European white storks Ciconia ciconia are called "grasshopper birds" in parts of Africa because they feast on swarms of the insects.
The hammerkop builds a domed, enclosed nest unique to the bird world. It can measure 6 feet (1.8 meters) around and weigh more than 100 pounds (45 kilograms)!
The old legend about storks bringing babies got started because the European white stork often nests on the roofs and chimneys of houses in the spring, a time when many babies are born. The bird became a symbol of fertility and was considered good luck.
Storks have a dignified appearance, standing graceful and tall or marching deliberately on slender legs. Nature has a good purpose for those long legs, of course: they allow the stork to take long strides and wade into deep water or tall grasses and reeds in search of food. A long neck allows them to stretch out to capture their prey.
Storks are also beautiful in flight. They fly mostly by soaring on warm air currents, with long, broad wings that only flap occasionally. They stretch their necks out and dangle their legs behind them as they fly, making them recognizable even from far away. Some storks have bare patches on their heads and necks.
In the scavenger species, this is thought to prevent feathers from getting stuck together with blood or mud, but the bare places are also used to impress, becoming more brightly colored during breeding season. Some storks also use their feathers in displays, like the woolly-necked stork Ciconia episcopus that has feathers to puff out around its throat like a ruffed collar.
Colonies and couples
When it comes to breeding, storks may be either colony nesters or solitary nesters.
Colony nesters— These storks gather in large groups, from a few pairs to several thousand birds. They often share their breeding grounds with other species. In Africa, it’s not unusual to see large colonies of Abdim’s storks Ciconia abdimii, yellow-billed storks Mycteria ibis, and marabou storks Leptoptilos crumeniferus mixed in with pink-backed pelicans, herons, and egrets. It’s quite a party! And they can be noisy, too, since the storks do a lot of bill clacking, a courtship behavior in which they rattle the two halves of their bills together repeatedly and loudly.
Solitary nesters— Jabirus storks Jabiru mycteria, black-necked storks Ephippiorhynchus asiaticus, and Storm’s storks Ciconia stormi form a male-female bond that can last for many years, and nest by themselves. The pair often uses the same nest over and over again.
Most storks build their nests in trees, although some also use hollows in cliffsides or even grass thickets on the ground. For many species a new nest needs to be made each year, but some go back and use the same nest several years in a row.
Even so, they always add to it, which is why some stork nests are so big. Hammerkop pairs continually add sticks and twigs to their unique domed nests, even when they have no chicks or eggs to care for. The nests are mostly made of sticks, which the male finds and brings back and the female puts in place.
Some storks dig up patches of turf and place them inside the nest. Often, the male will bring a leafy green twig as the finishing touch after the construction is over—the stork version of home decorating! Stork nests can be huge, more than 9 feet (2.7 meters) deep and 6 feet (1.8 meters) wide in some cases. The storks aren’t the only ones using them—small birds like sparrows, starlings, and wrens make their own nests in spaces between the sticks.
Fluffy but hungry!
When stork chicks hatch they are almost naked, but they quickly develop a covering of fluffy down feathers. They are altricial and need their parents to care for them, so both parents are very busy flying back and forth to bring them food. They can eat up to 60 percent of their own body weight per day. If you weigh 80 pounds (36 kilograms), that would be like eating 48 pounds (22 kilograms) of food every day. Burp!
After about three or four weeks, the chicks start to stand up in the nest and flap their stubby wings. After a few months, their flight feathers start to grow in and they learn to fly. Even then, they are still dependent on their parents for food for several weeks, before they start fending for themselves.
For many species, the shape of their bills is related to what they eat. Scavengers like the marabou stork and greater adjutant stork Leptoptilos dubius have large, heavy, sharp-edged bills to tear meat off carcasses.
Storks that feed in murky waters, like the wood stork Mycteria americana and milky stork Mycteria cinerea, have sensitive areas on their bills that can feel prey brushing against it. They stalk slowly or just stand still with their bills in the water, and when they feel food, they snap it up.
Other species like the jabiru and the maguari stork Ciconia maguari have pointed bills used to jab at prey in water or tall grass. Shoebill storks Balaeniceps rex are often compared to statues as they stand perfectly still for long periods in marshes, waiting for a meal of fish to surface in the water. The storks at the San Diego Zoo and the San Diego Zoo Safari Park eat a variety of thawed fish, shellfish, and mice.
The open-billed storks Anastomus sp. have the most unusual eating habit. They have a curved opening in the middle of their bills that they use to eat their favorite food: aquatic snails. People used to think the stork picked up a snail and then crushed it, kind of like a nutcracker. But when the birds were studied, the empty snail shells weren’t crushed at all. It turns out that these storks use the upper part of the bill to hold the snail against the ground, while the lower part of the bill slices the muscle holding the snail in its shell. The snail is then pulled out and swallowed, leaving the shell intact. Open-billed storks also use this nifty trick to open clams and mussels.