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South Florida Wading Bird Study

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The University of Florida Wading Bird Project is part of a larger group of professionals and agencies that are cooperatively monitoring wading bird reproduction and responses to the Comprehensive Everglades Restoration Plan. Other partners include Florida Atlantic University, Everglades National Park, Audubon of Florida, the South Florida Water Management District, Loxahatchee National Wildlife Refuge, and Big Cypress National Preserve.

Each year, the results of system-wide surveys are made available in the South Florida Wading Bird Report compiled by the South Florida Water Management District (PDF 2005, 2006, 2007). We also create more comprehensive (PDF) within-agency reports, as well as reports to Congress.

The Everglades is highly variable from year to year, and the great value of wading bird monitoring in the Everglades is the length and continuity of the record, and in the spatial scale of the information. For some species and questions, comparisons can be made over 80 years worth of information.

Long-term monitoring often turns up ecological relationships and surprises that cannot be gleaned from short-term studies. Some of those for the Everglades wading bird work include:

  1. A substantial long-term decline in the numbers of birds nesting in the Everglades (80 - 90%) and movement of nesting away from the coast. These observations indicated a collapse of the estuary at least ten years before fisheries or coastal ecologists documented changes.
  2. Documentation of relationships between annual hydrological characteristics (drying extent and patterns, hydroperiod) and location, timing and success of nesting by wading birds. These patterns have fed directly into models for managing the Everglades.
  3. An unexpected increase in numbers of nesting pairs in the late 1990s and early 2000's of between 3 and 5 times normal. The increase has been prior to any substantial hydrological restoration activities and researchers are still working on explaining the phenomenon.
  4. A relationship between severe droughts and later pulses of nesting by birds. This finding has spurred an increase in work on nutrient dynamics and fish community ecology during droughts.
  5. An increase in mercury contamination in the early 1990s, and an equally unexpected decrease in mercury contamination beginning in 1998. Both processes are now explicable, but neither were predicted.
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PDF Frederick, P.C., B.A. Hylton, J.A. Heath and M.G. Spalding. 2004. A historical record of mercury contamination in southern Florida as inferred from avian feather tissue. Environmental Toxicology and Chemistry 23:1474-1478.

PDF Frederick, P.C. and J.C. Ogden. 2003. Monitoring wetland ecosystems using avian populations: seventy years of surveys in the Everglades. Pgs.321-350 in: D. Bush and J. Trexler, eds. "Monitoring ecosystems: interdisciplinary approaches for evaluating ecoregional initiatives". Island Press, Washington, DC. 447 pgs.

Heath, J.A. and P.C. Frederick. 2005. Relationships among mercury concentrations, hormones, and nesting effort of White Ibises. The Auk 122:255-267

Hylton, B.A, P. C. Frederick, T. E. Delafuente, and M.G. Spalding. 2006. Effects of nestling health on post-fledging survival of wood storks. Condor 108:97-106.

PDF Frederick, P.C., B. Hylton, M. Ruane and J.A. Heath. 2003. Accuracy and variation in estimates of large numbers of birds by individual observers using an aerial survey simulator. Journal of Field Ornithology 74:281-287.

PDF 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.

PDF Frederick, P. C., T. Towles, R. Sawicki and G. T. Bancroft. 1996. Comparison of aerial and ground techniques for discovery and census of long-legged wading bird (Ciconiiformes) nesting colonies in the Florida Everglades. Condor 98:837 - 841.

PDF Frederick, P. C., K. L. Bildstein, B. Fleury and J. C. Ogden. 1996. Conservation of nomadic populations of White Ibis (Eudocimus albus) in the United States. Conservation Biology 10:203 - 216.

Frederick, P. C. and G.V.N. Powell, III. 1994. Nutrient transport by wading birds in the Everglades. Pgs. 571 - 584 in: Everglades: the ecosystem and its restoration. S. Davis and J. C. Ogden (eds.) St. Lucie Press, Delray Beach, Florida.

PDF 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 77:212 - 219.

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