Mycteria americana

Genetic analyses yielded no evidence of discrete subpopulations in Florida (Stangel et al. 1990). Indeed, Van Den Bussche et al. (1999) found low levels of genetic variability among Georgia and Florida Wood Storks and recommended that "all colonies of Wood Storks in the southeastern United States be managed...as a single interbreeding population." Similar surveys of South and Central American populations are not available.

Large range from the southeastern U.S. and Mexico to South America; populations are relatively stable and apparently secure on a global basis; U.S. population has been stable in recent years, but nesting and feeding areas have been negatively impacted by human alteration of the natural hydrological conditions.

Resident from southern Sonora, Mexican Plateau (rarely), U.S. Gulf Coast (Florida, formerly west to Texas), and Atlantic coast (South Carolina to southern Florida), south in lowlands to South America (to western Ecuador, eastern Peru, Bolivia, northern Argentina), and Antilles (Cuba, Hispaniola). The southeastern U.S. population is probably disjunct from those in Mexico-Central America. Some individuals, especially juveniles, wander north after the breeding season; may occur up the Mississippi Valley to Arkansas and west Tennessee and up the Atlantic coast to North Carolina; Mexican breeders may range to Texas and Louisiana. Recent breeding in the U.S. has occurred in Florida, southeastern Georgia (Ruckdeschel and Shoop 1989, Bratton and Hendricks 1990), and South Carolina. Center of breeding range in the U.S. has shifted northward since the mid-1970s (Ogden et al. 1987); the Everglades has become of lesser importance as a breeding area but remains critical as a foraging area, especially during dry years (Ehrlich et al. 1992), when possibly as much as 55% of the total U.S. population may use the Water Conservation Areas north of Everglades National Park (at least 8-10% in wet years) (Bancroft et al. 1992). Southeastern U.S. breeders winter within the breeding range, rarely north to northwestern Florida and coastal Georgia. In the U.S., the highest winter densities occur in peninsular Florida (Gulf and Atlantic coasts) (Root 1988).

Occurs locally throughout range in North, Central, and South America.

A major problem is low productivity, associated with inadequate food, caused in part by disruption and drainage of wetlands (see Van Meter 1989). The U.S. population (especially Florida) is threatened by human manipulation of water regimes, affecting both nesting sites and feeding areas. The long reproductive lifespan of the wood stork allows it to tolerate reproductive failure in some years, but artificially modified hydrological regimes, exacerbated by naturally occurring events (e.g., prolonged drought or unseasonal heavy rainfall), have caused nesting failures to become chronic in some of the important south Florida rookeries. Additional loss of habitat stems from logging and development. Nest predation by raccoons has been a problem in some areas. Human disturbance causes adults to leave their nests, exposing the eggs/young to predators (Van Meter 1989).