Nesting Success of Five Ciconiiform Species in Relation to Water Conditions in the Florida Everglades


In 1986 and 1987, we studied the nesting success of five species of wading birds (Ciconiiformes) through repeated visits to a total of 1,609 marked nests in 18 colonies in the Florida Everglades. Abandonment was the most common cause of nesting failure for all species and usually occurred following heavy rainfall and periods of rising surface water. Using stepwise logistic regression, we found that rapid surface water drying rate was associated most strongly with White Ibis (Eudocimus albus) nesting success, and that amount of rainfall was directly associated with failure of Great Egret (Casmerodius alba) nests. From records of 32 past surveys of White Ibis nesting numbers in two different water management areas, we found that years with high nesting numbers had significantly faster spring drying rates than years with low nesting numbers. There was no significant difference in amount of spring rainfall, autumn/winter drying rate, or water depth. Abandonments by ibises appeared to be closely related to prey densities, which probably were directly affected by water-level fluctuations.

The Auk