Wood Storks (Mycteria americana) 1
Background
The wood stork, also known as wood ibis or flint head, is one of the largest wading birds found in Florida and the only stork in the United States. Description
This stork stands more than 3.5ft (107cm) tall with a wingspan of more than 5ft (150cm). The wood stork's body is white except for a short black tail and black feathers that border the wings ( Figure 1 ). The long stout bill is 6-9in (15-23cm) long and is grayish-black on adult birds, yellowish on young storks. Figure 1.
Distribution
U.S. wood storks occur in tropical and subtropical wetlands, with colonies in Florida, Georgia, and South Carolina at the northern edge of the species' range. Wood storks still occur--but no longer breed--in Texas, Louisiana, Mississippi, and Alabama. Their range extends south to northern Argentina. Following the nesting season wood storks can be seen throughout the U.S. southeastern coastal plain. Habitat
Wood storks are wetland dwellers and use fresh, brackish, and salt water habitats for feeding and nesting. Feeding takes place in shallow ponds, tidal pools, swamps, and marshes. Nesting occurs in cypress, hardwood, and mangrove swamps. Feeding
A wood stork feeds by touch. Standing in 6-20in (15-51cm) of water with its submerged beak open 2-3in (5-8cm), the wood stork gropes for its prey ( Figure 2 ). This usually consists of fish, occasionally crayfish Figure 2.
and amphibians, and even baby alligators and snakes. Prey are startled from hiding places in vegetation by foot stirring. This mechanical method is clearly advantageous in turbid, heavily vegetated marsh. However, enough prey must by present for this method to be effective during the breeding season. Adult wood storks eat about a pound of food per day when not nesting, but during the nesting season need about 440lb (200kg per pair to feed themselves and fledge their young. Wood storks often travel about 15-40mi (24-64km) per day seeking areas in which to feed.
Nesting
Wood storks nest in colonies from a few to hundreds of nests. Nests are thin platforms of sticks lined with twigs and leaves built near the tops of trees or shrubs, sometimes as high as 100ft (30m). Timing of nesting depends on wetland water levels. In southern Florida nesting can occur as early as December, later during wet years or in other areas, and continues for about 130 days. Up to five eggs may be laid, but three is average. The parents alternate incubating the eggs for about 30 days. Young storks are fed regurgitated fish. On hot days adults also disgorge water over the nestlings to cool them. Young storks fledge in about 55 days. Wood storks fly with their legs and neck outstretched ( Figure 3 ). Figure 3.
Population Size and Trends
Until the last few decades the wood stork was a common sight in Florida wetlands, largely because they had escaped harvest by plume hunters that so decimated the egret. Although the exact figure is not known, the total number of wood storks in the U.S. in the 1930s was estimated at 60,000. By 1960 only an estimated 11,000 pairs nested in Florida. According to current estimates by the National Audubon Society, there are about 4,000 to 5,000 nesting pairs in the U.S. The picture in south Florida is much bleaker with wood storks rarely reproducing successfully. One reason for the decline in the wood stork population has been the changes in the hydrologic regime of the Everglades. This affected foraging habitat and food production. Historically, the wood stork's nesting cycle coincided with natural patterns of rain and drought. Summer rains and rising water levels dispersed fish throughout the wetlands. During the winter and spring dry season, these fish would concentrate in shallow pools. This cycle provided wood storks with an abundant and easily obtainable food supply during the nesting season. In south Florida, where most of the wood storks have nested, this cycle has been altered. Water management has alternately drained or flooded former wood stork feeding habitat, for flood control and water supply. When food is limited before nesting season, wood storks will not nest. If they do nest, and their food supply fails, they abandon the nesting colony to find better feeding conditions. This failure to produce young limits the number of storks available to replace those in the breeding population that may die. Wood Storks as Environmental Indicators
The extreme dependence of the wood stork on a naturally functioning hydrologic regime of the southern Florida wetlands makes it an excellent indicator of the health of the Everglades. In fact the National Audubon Society calls the wood stork "the barometer of the Everglades." Protection
In 1984 wood storks were listed as endangered by the U.S. Fish and Wildlife Service (FWS), under the Federal Endangered Species Act. Wood storks also are listed as endangered by the State of Florida. As the human population of Florida grows, the pressure on the remaining wetlands continues. The best hope for wood storks is an educated and active citizenry to help ensure that the needs of wetland-dependent wildlife such as wood storks are planned for in the management of Florida's growth. Suggested Reading
Ogden, J.C. and C. Singletary. 1983. The Abundant, Endangered Flinthead. Audubon. Vol. 85 pp.90-101. VanMeter, V.B. 1985. Florida's Wood Storks. Florida Power and Light Co. Corporate Communications, Miami, FL. Endnote
The drawings in Figures 1, 2, and 3 were reprinted from Florida's Wood Storks. Footnotes
1. This document is SSWIS12, one of a series of the Wildlife Ecology and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date December, 1990. Revised September, 2002. Reviewed April, 1999. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.
2. Frank J. Mazzotti, Ph.D., associate professor, Wildlife Ecology and Conservation department, University of Florida, Everglades REC, Belle Glade, FL 33430, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.The Institute of Food and Agricultural Sciences (IFAS) is an Equal
Opportunity Institution authorized to provide research, educational
information and other services only to individuals and institutions
that function with non-discrimination with respect to race, creed,
color, religion, age, disability, sex, sexual orientation, marital
status, national origin, political opinions or affiliations.
For more information on obtaining other extension publications,
contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service,
University of Florida, IFAS, Florida A. & M. University Cooperative
Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
