Figure 1. Normal breeding and nonbreeding range of the White Ibis.
The White Ibis is a striking, white wading bird with a long, distinctively decurved bill. It usually nests, feeds, and flies in large conspecific flocks, and in many ways epitomizes the freshwater and coastal wetlands of the southeastern United States. Historically one of the most abundant of North American wading birds, it still maintains large regional populations with a few nesting colonies of 20,000–30,000 pairs.
This is a bird of freshwater and estuarine wetlands—typically cypress swamps, bottomland hardwood and mangrove swamps, as well as freshwater marshes and salt marshes. Ibises are known for frequent shifts in roost and colony sites ( Bildstein, K. L. (1990). Status, conservation and management of the Scarlet Ibis, Eudocimus ruber in the Caroni Swamp, Trinidad, West Indies. Biol. Conserv. 54:6178.
Bildstein 1990, Gehlbach, F. R. (1981). Mountain islands and desert seas: a natural history of the U.S.-Mexican borderlands. College Station: Texas A&M Univ. Press.
Gehlbach 1981), substantial dispersal and migration distances ( Frederick, P. C., K. L. Bildstein, B. Fleury and J. Ogden. (1996). Conservation of large, nomadic populations of White Ibises (Eudocimus albus) in the United States. Conservation Biology 10 (1):203-216.
Frederick et al. 1996, Melvin, S. L., D. E. Gawlik and T. Scharff. (1999). Long-term movement patterns for seven species of wading birds. Waterbirds 22 (3):411-416.
Melvin et al. 1999) and variable breeding seasons ( Heath, J. A. (2002). White Ibis (Eudocimus albus) reproductive physiology. Ph. D. dissertation, University of Florida, Gainesville, FL.
Heath 2002, Piazza, B. P. and V. L. Wright. (2004). Within-season nest persistence in large wading bird rookeries. Waterbirds 27 (3):362-367.
Piazza and Wright 2004, Frederick, P. C., J. A. Heath, R. Bennetts and H. Hafner. (2006). Estimating nests not present at the time of breeding surveys: an important consideration in assessing nesting populations. Journal of Field Ornithology 77 (2):212-219.
Frederick et al. 2006). Nomadic movements and flexible reproductive schedules allow ibises to exploit the changing availability of shallow water feeding sites and concentration of its main prey, crustaceans and small fishes ( Kushlan, J. A. (1979d). Feeding ecology and prey selection in the White Ibis. Condor 81:376-389.
Kushlan 1979d, Gawlik, D. E. (2002). The effects of prey availability on the numerical response of wading birds. Ecological Monographs 72 (3):329-346.
Gawlik 2002). Because of salt stress, nestlings do not develop normally on brackish water crustaceans, so nearby freshwater feeding sites are essential for successful breeding at coastal colonies ( Johnston, J. W. and K. L. Bildstein. (1990). Dietary salt as a physiological constraint in White Ibises breeding in an estuary. Physiol. Zool. 63:190-207.
The dependence of White Ibis on favorable feeding conditions in wetlands, the conspicuous nature of their large flocks and colonies, and their eye-catching appearance has made the species a symbol for wetland conservation and restoration, especially in Florida where ibis habitat is threatened by development, pollution, and water management. Numerous studies have investigated trends in White Ibis distribution, abundance and reproductive success ( Crozier, G. E. and D. E. Gawlik. (2002). Avian response to nutrient enrichment in an oligotrophic wetland, the Florida Everglades. Condor 104 (3):631-642.
Crozier and Gawlik 2002, Crozier, G. E. and D. E. Gawlik. (2003b). Wading bird nesting effort as an index to wetland ecosystem integrity. Waterbirds 26 (3):303-324.
Crozier and Gawlik 2003b, Frederick, P. C. and J. C. Ogden. (2001). Pulsed breeding of long-legged wading birds and the importance of infrequent severe drought conditions in the Florida Everglades. Wetlands 21 (4):484-491.
Frederick and Ogden 2001, Frederick, P. C., J. A. Heath, R. Hylton, J. D. Semones, G. Babbitt and M. Spalding. (2001). Factors affecting breeding status of wading birds in the Everglades. Jacksonville, FL: U. S. Army Corps of Engineers.
Frederick et al. 2001, Frederick, P. C. and J. C. Ogden. (2003). "Monitoring wetland ecosystems using avian populations: Seventy years of surveys in the Everglades." In Monitoring Ecosystems: interdisciplinary approaches for evaluating ecoregional initiatives, edited by D. Bush and J. Trexler, 321-350. Washington, D.C.: Island Press.
Frederick and Ogden 2003, Stolen, E. D., D. R. Breininger, P. C. Frederick and S. A. Bortone. (2005). "Using waterbirds as indicators in estuarine systems: successes and perils." In Estuarine indicators., edited by S. Bortone, 409-422. Boca Raton, FL: CRC Press.
Stolen et al. 2005, Herring, G. (2008). Constraints of landscape level prey availability on physiological condition and productivity of Great Egrets and White Ibises in the Florida Everglades. Ph.D. dissertation, Florida Atlantic University.
Herring 2008), and/or ibis contaminant levels ( Frederick, P. C., M. G. Spalding and R. Dusek. (2002). Wading birds as bioindicators of mercury contamination in Florida, USA: Annual and geographic variation. Environmental Toxicology and Chemistry 21 (1):163-167.
Frederick et al. 2002, Frederick, P. C., B. Hylton, J. A. Heath and M. G. Spalding. (2004a). A historical record of mercury contamination in southern Florida (USA) as inferred from avian feather tissue. Environmental Toxicology and Chemistry 23 (6):1474-1478.
Frederick et al. 2004a, Heath, J. A. and P. C. Frederick. (2005). Relationships among mercury concentrations, hormones, and nesting effort of White Ibises (Eudocimus albus) in the Florida Everglades. Auk 122 (1):255-267.
Heath and Frederick 2005, Rodgers, Jr., J. A. (1997). Pesticide and heavy metal levels of waterbirds in the Everglades Agricultural Area of south Florida. Florida Field Naturalist 25 (2):33-41.
Rodgers 1997), and used this information to infer ecosystem health.
No subspecies are recognized, but the Scarlet Ibis (Eudocimus ruber) of South America is closely related and is considered by some to be a conspecific color morph.