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Mycteria americana Linnaeus, 1758
Wood Stork
Federal Protection: Listed Threatened
State Protection: Endangered
Global Rank: G4
State Rank: S3
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: High Conservation Concern
Element Occurrences (EOs) in Georgia: 49
Habitat Summary for element in Georgia: Cypress/gum ponds; impounded wetlands with islands or emergent cypress; marshes; river swamps; bays
The wood stork is a very large, long-legged wading bird about 85-113 cm (33-44 in) in height with a wingspan of 150-165 cm (59-65 in), and a large, down-curved bill. The plumage is mostly white, but the wing-tips, trailing edge of the wings, and tail are black with a greenish sheen. Legs are black, but the toes are pink. The neck and head of adults is not feathered, and the skin is grayish black with a scale-like appearance; the bill is also grayish black in color. Juveniles have a yellow bill, and the head and neck are covered with sparse, hair-like feathers. The bill gradually darkens, and the feathers on the head are lost with full adult plumage reached in the bird's fourth year. Male and female plumages are similar.
The adult white ibis (Eudocimus albus) can look similar to the wood stork from a distance and in flight but is substantially smaller (63 cm; 25 in long) with pinkish-red to pinkish-orange face, bill, and legs, and only the very tips of the wings are black. Also, white feathers cover the neck and top of the head. Juvenile white ibis have a dark head, bill, and legs and a white rump. The upper surface of the wings and the upper back are dark brown while the undersides of the wings are white with a dark brown trailing edge, which can look similar to that of the wood stork.
Wood storks use a variety of freshwater and estuarine wetlands for breeding, feeding, and roosting. They are colonial nesters, and several nests are often located in the same tree. Colony size in Georgia has ranged from fewer than 12 to more than 500 nests. They are typically located in trees in standing water or on islands 1-20 m (3-66 ft) above the water. Storks will occasionally use the same large colonies for many years, but most colonies are shorter lived, and many are established and abandoned after a single year; few last more than 20 years. The longest-lived colonies in Georgia are deep water ponds with vegetated islands. These sites are typically manmade and managed impoundments that maintain deep water even in relatively dry years. Water levels of natural wetland sites tend to fluctuate dramatically year to year, making their use by storks less predictable. When water levels are low, predators such as raccoons can access nesting trees and wood storks often forego nesting or abandon their nests early in the nesting season.
Primarily fish; sometimes amphibians (mostly tadpoles), crayfish, crabs, grass shrimp, beetles, grasshoppers, snakes, small alligators, and other small aquatic animals. Rarely birds including rails and grackles and small mammals including mice, rats, and shrews.
Wood storks feed using a technique known as tacto-location or grope feeding. Usually this involves wading through shallow water with a partially-opened bill or probing into the water. When the bill touches a fish, or other prey, it snaps shut with a rapid reflex motion, one of the fastest known for vertebrates. In addition, they will also feed by holding their bill still and stirring the sediment with their feet and often shuffle their feet and flash their wings to startle prey. Tacto-location is particularly effective in turbid water where it would be impossible to see prey. Preferred prey include fish from about 2 to 25 cm (0.7-10 in) in length. This feeding strategy is very effective during seasonal (or tidal) drawdowns of wetlands when fish are concentrated in shallow pools. In southern Florida, the onset of breeding begins at the start of the dry season, when drying wetlands concentrate prey. The birds depend on successive drying of the wetlands to provide adequate food to raise their young, and rising water levels can cause the adults to abandon nestlings, which subsequently starve. Wood storks use a variety of feeding sites in both freshwater and estuarine wetlands to obtain adequate food. In coastal Georgia, storks feed in small tidal creeks at low tide when fish, especially mummichogs (Fundulus heteroclitus), are presumably concentrated. Storks often forage at considerable distances from the nesting colony. The birds take advantage of thermal updrafts to soar and glide to feeding sites. Birds followed to feeding sites from a colony in east-central Georgia usually chose sites that were within 20 km (12 mi) of the colony, but occasionally foraged as far as 29 km (18 mi) from the colony. In Georgia breeding usually begins in March. Clutch size ranges from 2 to 5 eggs (usually 3), and incubation takes about 27-32 days. After hatching, one adult remains with the young, shading the chicks from the sun when necessary. Both adults feed the young by regurgitating food onto the nest platform. Young storks begin learning to fly at about 8 weeks of age; however, the young often remain at the colony and return to the nest platform to be fed by adults until they are around 12 weeks old. Although a few birds have been documented to breed in their third year, most do not breed until their fourth year when adult plumage is attained. The maximum longevity of a bird in the wild is over 20 years, but the wood stork may live to over 30 years of age in captivity. There are currently several birds that are more than 20 years old still nesting every year at Harris Neck NWR.
Conduct aerial surveys of all known nesting sites in early May to determine the number of active nests. Survivorship and productivity can be assessed at selected sites and used as an index of overall population health. Banding chicks at select sites can provide additional data such as site fidelity, dispersal, breeding age, and longevity. Unmanned Aerial Vehicles (UAVs) have been used to monitor stork colonies at some remote sites.
The wood stork's breeding range includes the southeastern U.S., both coasts of Mexico and Central America, Cuba, Hispaniola, and South America from Colombia to Argentina. In the U.S., it breeds in Florida, Georgia, South Carolina, and North Carolina. This species was first recorded nesting in Georgia in 1965 at Blackbeard Island NWR. Breeding colonies have been documented at least once at 56 different locations in 18 counties primarily along the coast or in southwest Georgia. Following the breeding season, wood storks may disperse northward to North Carolina, Tennessee, and Arkansas. A few wood storks may be seen in the Georgia Piedmont, well north of breeding colonies, during late summer and fall, but the most heavily used habitat during fall is coastal marshes. Beginning in late summer, wood storks from many widely separated breeding colonies gather into communal roosts along the coast. Over 100 birds may roost at favored sites, which are used year after year. The birds rest at the roost during high tide and move out into the saltmarsh to feed during low tide. Birds that nested in Georgia have been tracked south to southern Florida in winter; however, in most years a few birds remain along the coast in McIntosh, Glynn, and Camden counties.
The breeding population of wood storks in the southeastern U.S. declined from an estimated 15,000-20,000 pairs in the 1930s to a low of 4,500-5,700 pairs from 1977-1980. The lowest annual estimate occurred in 1978 when 2,500 pairs bred. However, this probably reflected the combined influence of a low population and poor nesting conditions; many storks may not have attempted to breed that year. Prior to the mid-1970s, nesting in Georgia was sporadic with only small numbers of nesting birds. Nesting in South Carolina did not start until 1981. As large colonies in southern Florida steadily declined in the early 1980s the number of nesting birds in South Carolina and Georgia steadily increased resulting in a shift of the breeding distribution of this species. Loss of habitat is the primary threat to stork populations. In addition to direct loss of feeding habitat through draining and filling of wetlands, the disruption of the natural cycle of seasonal drying in southern Florida is believed to have caused the loss of major breeding colonies in Everglades National Park. Although wood storks benefit from seasonal drying of foraging habitat, water levels in the colony must remain deep enough to prevent access by predators. When a nesting colony dries up, raccoons are able to invade the area and eat the storks' eggs or young. This dependence on several types of wetlands (deep water for nesting and shallow water for foraging) makes storks particularly vulnerable to wetland loss, and fluctuations in rainfall. Human disturbance and contaminants are other potential threats.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Natural system modifications | Climate change & severe weather | Natural system modifications |
| Specific Threat | Dams & water management/use | Habitat shifting & alteration | Other ecosystem modifications |
While recent years have seen declines from our high count of nests in 2014, the overall trend in the state is still positive. It does appear that numbers to our north (breeding in South Carolina and North Carolina) have increased while Georgia numbers have declined, perhaps indicating an ongoing northward expansion of the breeding range. Productivity data has been collected for many years in Georgia from over 30 different colonies. Productivity measures surpassed the recovery target of 1.5 chicks per pair in 21 out of 29 survey years. Typically, coastal colonies (within 20km of the coast) have slightly higher productivity than inland colonies, perhaps due to more predictable access to food in the intertidal zone. Range-wide wood stork numbers continue to grow, and Georgia clearly represents a significant part of the recovery of the species.
The U.S. Fish and Wildlife Service's Recovery Plan goal for down-listing the wood stork from endangered to threatened was a population of 6,000 pairs (3-year average) and regional productivity greater than 1.5 chicks per nest. They were officially downlisted to threatened in 2014. The goal for delisting is 10,000 pairs (5-year average), with regional productivity greater than 1.5 chicks per nest, and 2,500 successful pairs in south Florida. Recovery tasks include identification and protection of existing foraging and nesting habitat, restoration of historically important habitat in the Everglades, and monitoring of the population through periodic surveys. The Georgia population averaged 1,922 pairs per year from 2011-2018. The largest nesting effort ever recorded in the state occurred in 2014 when a total of 2,950 pairs nested in 22 colonies. Numbers dropped following 2014 with a low of 1594 pairs nesting in Georgia in 2018 but have rebounded with 2564 nests in 2019. This pattern fits an overall all positive trend for nesting pairs in Georgia, but with significant variability year to year. On a local scale, management of artificial feeding lakes and construction of artificial nesting structures where nest trees have been lost can enhance wood stork reproductive success. Both have been used effectively at Harris Neck National Wildlife Refuge on the Georgia coast, which coincidentally is the best site in the state to view this species. Protection of breeding colonies is critical for recovery of the wood stork. Habitat management guidelines developed by the U.S. Fish and Wildlife Service provide information on buffers for nesting colonies and important roost sites. Most stork colonies are located on private land, so working with private landowners is important for their long-term conservation.
Bryan, A. L., Jr. 1994. Wood stork roost sites in the coastal zone of Georgia and South Carolina in 1994. Report to the U.S. Fish and Wildlife Service, Savannah Coastal Refuges, Savannah, GA. 17pp.
Bryan, A. L., Jr., and M. C. Coulter. 1987. Foraging flight characteristics of wood storks in east-central Georgia, U.S.A. Colonial Waterbirds 10:157-161.
Comer, J. A., M. C. Coulter, and A. L. Bryan, Jr. 1987. Overwintering locations of wood storks captured in east-central Georgia. Colonial Waterbirds 10:162-166.
Coulter, M. C., W. D. McCort, and A. L. Bryan, Jr. 1987. Creation of artificial foraging habitat for wood storks. Colonial Waterbirds 10:203-210.
Hancock, J. A., J. A. Kushlan, and M. P. Kahl. 1992. Storks, ibises, and spoonbills of the world. Academic Press, Harcourt Brace Jovanovich, London. 385pp.
Harris, M. J. 1995. Status of the wood stork in Georgia, 1965-1993. Pages 34-46 in Proceedings of the Wood Stork Symposium. The Georgia Conservancy, Savannah, GA.
Harris, M. J. 1999. Wood Stork (Mycteria americana). Pp. 52–53 in T. W. Johnson, J. C. Ozier, J. L. Bohannon, J. B. Jensen, and C. Skelton, eds., Protected Animals of Georgia. Georgia Department of Natural Resources, Wildlife Resources Division, Nongame Wildlife–Natural Heritage Section, Social Circle.
Kahl, M. P. 1964. Food ecology of the wood stork (Mycteria americana) in Florida. Ecological Monographs 34:97-117.
Kushlan, J. A. 1976. Wading bird predation in a seasonally fluctuating pond. Auk 93:464-476.
Murphy, T. M. 1993. Status of the wood stork in South Carolina. Pages 30-33 in Proceedings of the Wood Stork Symposium. The Georgia Conservancy, Savannah, GA.
Ogden, J. C. 1993. Wood stork symposium keynote address: An overview for protection and recovery of the wood stork. Pages 10-18 in Proceedings of the Wood Stork Symposium. The Georgia Conservancy, Savannah, GA.
Ogden, J. C., D. A. McCrimmon, Jr., G. T. Bancroft, and B. W. Patty. 1987. Breeding populations of the wood stork in the southeastern United States. Condor 89:752-759.
Robinette, J. R., J. P. Davis, and J. L. Hall. 1993. U.S. Fish and Wildlife Service wood stork enhancement and restoration projects in coastal Georgia. Pages 57-63 in Proceedings of the Wood Stork Symposium. The Georgia Conservancy, Savannah, GA.
Tsai, R., P. Frederick, and K. D. Meyer. 2011. Finding Wood Stork Habitat and Conserving the Right Features. Final Report for Georgia Department of Natural Resources, Brunswick, GA.
U.S. Fish and Wildlife Service. 1996. Revised recovery plan for the U.S. breeding population of the wood stork. U.S. Fish and Wildlife Service, Atlanta, Georgia. 76pp.
Winn, B., and J. C. Ozier. 2010. Wood Stork (Mycteria americana). Pp. 114–115 in T. M. Schneider, G. Beaton, T. S. Keyes, and N. A. Klaus, eds. The Breeding Bird Atlas of Georgia. University of Georgia Press, Athens.
Michael J. Harris, Bradford Winn, James C. Ozier, Todd M. Schneider, and Andy Day
M. Harris, 1999: original account
B. Winn and J. Ozier, 2010: Breeding Bird Atlas species account
T. Schneider, July 2010: modified and edited text
K. Owers, July 2010: updated status and ranks, added picture
A. Day, November 2019: updated status and ranks, modified text