By: M. Kathy Raines
Special to the PARADE
A cluster of four unfamiliar shorebirds—tall, hefty ones with black-trimmed white feathers—foraged in crab-filled puddles along the ship channel at Jaime J. Zapata Memorial Boat Ramp early one July afternoon. They weren’t the customary waders—egrets, ibises, spoonbills and herons—and we’re certainly too southerly for whooping cranes. I wondered.
Then, in a magnified view, massive, tapered gray bills emerged from dark bald heads. Aha, this was a gathering of visiting wood storks, a species I’d never seen. Then, as I crept nearer and nearer with my camera—a little too close, I’m afraid—they flew off, one by one, winging westward, feet and bills outstretched—a stunning sight.
Our batch of visiting storks, which breed, most likely, in Mexico, wander for weeks or months to feed in sufficiently shallow and fruitful waters before settling into winter homes, perhaps on their breeding grounds, perhaps elsewhere. This July and August have brought multiple sightings, including ones at Laguna Atascosa and Santa Ana wildlife refuges.
A veritable Grand Central Station for birds, the Rio Grande Valley, with its rich food sources, invites a continual swirl of avian comings and goings—a boon for birds and a delight to their fans. Besides our treasured locals like green jays and Harris’s hawks, other birds, including grooved-billed anis and scissor-tailed flycatchers, flock here to breed during our prey-rich summers. Various hawks, sandpipers, ducks and white pelicans, to name a few, spend winters here. Warblers and other passerines (perching birds) drop off to feed and rest amid exhausting spring and fall migrations. And wandering wood storks enjoy summer sojourns.
Birders need not pore over field guides to recognize the wood stork (Mycteria americana), nicknamed “flinthead”, as it is one of a kind. The mosaic of patterns on its scaly grey head and neck, rather like those of a black vulture, suggest a cobblestone street. Its long, dark bill, massive at its base, ends in a slight downward curve. Dark rings encircle deep brown eyes. Long legs support its football-shaped body, white splashed with black. A stork may be over 3 ½ feet tall with a wingspan of 5 feet.
The wood stork—the only North American stork—breeds in coastal Mexico and much of South America, as well as in a few states—Florida, Georgia, South Carolina and, as of recently, North Carolina. Evidently, it hasn’t bred in Texas since 1960. Ideally, wood storks nest in tall trees, often cypress or oak, surrounded by shallow water and, most favorably, that populated by alligators. Though a gator may occasionally snatch up an unfortunate chick, it also provides the storks with protection against nest predators like raccoons and skunks.
A male stork appears at possible nest sights, interacting with females, till he finds a mate, with whom he remains for one season. The pair preen one another and engage in various displays. Colonial nesters, storks may raise young among anhinga, great egrets and great blue herons, among other waterbirds. The couple builds the foliage-lined twig nest together, and they both incubate the usual five eggs and care for chicks.
Nestlings, born altricial (in need of care), are covered with white down, except on the tops of their heads. Parents shade and protect them from rain. To cool chicks, they vomit water over them. Hungry, insistent nestlings, raising and lowering their bills, bray a high-pitched Nyah.
Wading in shallow water, the wood stork submerges its open bill—sometimes up to its nares (nostrils)—which it swings from side to side till it snaps shut onto prey such as fish, frogs, turtles, large insects, crabs, small snakes or alligators. Being primarily a tactile feeder, it successfully forages in dark or murky water. The stork may stir up prey by pumping one foot up and down, then the other.
Wood storks are usually quiet, except during courtship, when they clatter, snap bills or make low rasping sounds. At take-off, storks may make gooselike calls, and one hears the whoosh of air passing through their wings. Like other birds, the stork exhibits an assortment of agonistic (combative) displays and actions. In its “forward threat”, it stalks toward an intruder, faces it and shakes its head. In its “snap display”, it stands, suddenly lifts its head, with its bill horizontal to or above that of its opponent, and audibly snaps its bill. In an “areal clattering threat”, the stork—neck extended and bill, which it lifts and clatters, forward— flies behind, then above an opponent.
The wood stork is an indicator species, or one whose welfare reflects how others are faring. While the U.S. Fish and Wildlife Service listed the stork as “endangered” in 1984, it changed the bird’s status to “threatened” in 2014 after successful attempts at wetland restoration, including maintenance of appropriate water levels. Nestlings that don’t fledge before rainy seasons may drown. In the early 1900s, hundreds of thousands of wood storks nested in Audubon’s Corkscrew Swamp Sanctuary in Florida, but, in recent decades, storks have opted to nest elsewhere. This video, “Flight of the Wood Stork” (https://www.youtube.com/watch?v=wWbPkUGZPVg), aptly demonstrates the steps naturalists are taking to encourage storks to resume breeding in the park.
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