Gallery: Wood Stork - September/October 2017 [5 Images] Click any image to expand.
A juvenile wood stork flying south; below lef t, a female and male roosting in South Florida; below right, an adult wood stork foraging. Photo by William R. Cox.
Worldwide there are 19 species of storks. The wood stork (Mycteria americana) is the only one found in the United States. It is federally listed as threatened by the U.S. Fish and Wildlife Service (USFWS), which upgraded it from endangered on June 30, 2014. Historically its breeding range extended from eastern Texas eastward along the southern tier of the Gulf of Mexico coast. It has always nested primarily in Florida, but small breeding populations have been found in southern and southeastern Georgia and into extreme southern South Carolina.
The adult wood stork is large, standing 5.0-5.5 feet tall, 35-45 inches long, with a wingspan of 60-65 inches. The female is slightly smaller than the male. The coloring on the stork is predominantly white with iridescent black primary and secondary wing feathers and tail. Its head, neck and legs are blackish to gray; the head is scaly and featherless, featuring dark brown eyes. Its black bill decurves to a blunt point and is heavy in appearance. Its feet are pinkish. During the breeding season (November through May) its toes brighten to a distinctive salmon color. The juvenile wood stork has a straw-colored bill and is slightly grayish in body color. It also has scattered dusky feathers on the neck and head.
Species that are similar in appearance to the wood stork when in flight are the white pelican (Pelecanus erythrorhynchos) and the rare whooping crane (Grus americana). The white pelican is present throughout Florida during the wood stork’s breeding season. While it is also white with black primary and secondary wing feathers, the white pelican is larger than the wood stork and has a large yellow bill that is evident even in flight. Its legs, however, do not extend beyond its white tail feathers during flight, while the wood stork’s legs extend beyond its black tail feathers. The whooping crane is very rare and has a red crown on a white feathered head. It has less extensive black on its wings, but its legs do extend past its white tail feathers when flying.
Photo by William R. Cox.
Habitat for the wood stork includes cypress swamps, freshwater wetlands, ponds, streams, mangroves, flooded agricultural fields and artificial sites such as impoundment islands and coastal islands. Nesting colonies are scattered throughout Florida in these habitats. Large nesting colonies are found in south Florida in pristine swamplands such as Everglades National Park and National Audubon’s Corkscrew Swamp Sanctuary. According to the USFWS, there are two nesting colonies in Lee County, three in Charlotte County and five in Collier County. These colonies have a core foraging area of 18.6 miles, though nesting wood storks will fly up to 80 miles if needed to forage and bring food back to their nests. The two nesting colonies in Lee County are located at the upper reaches of the Caloosahatchee River. Wood storks foraging in Cape Coral during the nesting season could be from these colonies.
Wood stork foraging is dependent on normal flooding for prey expansion and drawdowns to concentrate prey such as fish, aquatic invertebrates, amphibians and reptiles in shallow bodies of water. They forage in a wide variety of shallow wetlands when these ephemeral bodies of water are 2-15 inches deep during their drying cycle. Prey consists primarily of fish 1-10 inches in length, including more than a dozen dominant species. Wood storks feed by tactolocation, moving their partially open and submerged bill from side to side, rather than by sight. Prey is grasped when it touches the wood stork’s bill. Tactile feeding behavior enables feeding at night and in turbid water. The young are fed regurgitated prey 3-10 times per day.
It is critical that wood stork nesting habitat has three to five feet of water throughout the nesting cycle. The clutch size is one to six eggs laid every other day; they are incubated for 28 days. Nestlings fledge nine weeks after hatching, and fledglings return to the nest for 15-30 days. Terrestrial predators such as raccoons could decimate the production of young if not for this deep-water protective barrier. This water depth is not only a physical barrier, but also supports alligators, which are a significant deterrent to terrestrial predators.
Photo by William R. Cox.
The greatest threat to wood storks today is the destruction of nesting and foraging wetlands and hydrological alterations to the landscape, reducing foraging and nesting habitat. Proactive management should include protection of nesting habitat, providing artificial structures for nesting where necessary, maintaining proper water levels in nesting and foraging habitat and manipulating gradual drawdowns in foraging habitat within 25 miles of nesting colonies.
Written by William R. Cox, a professional nature photographer and ecologist of more than 35 years. Visit him online at williamrcoxphotography.com.