The Wood Stork

by James L. Cummins

The wood stork is a large wading bird. Though it was once known as the “wood ibis,” it is not really an ibis. Wood storks are tall and white with long legs and featherless, dark-gray heads. They have long, thick, down-curved bills and extensive black flight feathers. Wood storks weigh up to 6 pounds with a body length up to 45 inches and a wingspan stretching up to 6 feet. The wood stork has a life span between 11 and 18 years in the wild.

The wood stork is the only stork that presently breeds in North America. Here in the United States, there is a small endangered breeding population. The wood stork breeds during the late winter dry season when its fish prey are concentrated in shrinking pools.

A soaring bird, the wood stork flies with its neck and legs extended. It forages where lowering water levels concentrate fish in wetlands. The wood stork walks slowly and steadily in shallow water seeking its prey. It hunts small fish, tadpoles, frogs, and crayfish by wading with its bill open just under the water’s surface, snapping it shut in as little as 25 milliseconds when encountering prey.

Favoring cypress trees in marshes and swamps, the wood stork builds a large nest in the top of a tree using sticks, vines, and moss. These storks nest colonially with up to 25 nests in one tree.

Breeding only once a year, the female lays 3 to 5 white eggs. The eggs are then incubated for 27 to 32 days. The chicks are hatched weighing around 2 ounces. The chicks are helpless and unable to fly. Competition for food is intense, and if food sources are low, then only the older chicks will survive. Week-old chicks grow rapidly and are fed up to 15 times a day. By 14 days, the chicks will weigh 10 times their hatching weight. At 28 days, they are 25 times heavier.

During the breeding season, wood storks need over 400 pounds of fish to feed themselves and their offspring. During warmer weather, parents also have to collect water and bring it to the nest to drool on and into the mouths of the chicks. By the time the young are 4 weeks old, both parents will leave the nest to search for food. This continues until the chicks “fledge” or leave the nest. The young may continue to return to the colony for up to 15 days after fledging to roost or try to get food from their parents. A colony is considered successful if the adult’s average at least 1.5 fledged young per nest.

While the young are still under their parents’ care, the adult will defend the nest against various predators such as vultures, striped skunks, crows, and blackbirds. However, raccoons are the leading predator of nests and can cause complete colony nesting failure when water dries under nests in drought years. Adults are rarely preyed upon but are sometimes picked off by American alligators.

James L. Cummins is executive director of Wildlife Mississippi, a non-profit, conservation organization founded to conserve, restore, and enhance fish, wildlife, and plant resources throughout Mississippi. Their web site is www.wildlifemiss.org.

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