Importance of Crayfish Prey to Nesting White Ibis (Eudocimus albus)

摘要

Wading bird prey populations, prey availability and wading bird nesting success are all thought to be associated with hydrologic conditions in wetlands, but the relationship between successful nesting and essential prey types fed to chicks is poorly understood in many cases. Prey fed to White Ibis (Eudocimus albus) chicks were quantified and compared for three colonies in the northern Everglades within and between the 2008 and 2009 nesting seasons. Crayfish were the dominant prey type in both years, being present in 58-88% of chick boluses across all collections. Prey composition was not temporally variable within 2008, but chick diet shifted slightly toward more fish at the end of 2009 when the wetland was at its driest. Crayfish were the dominant (55-65%) energetic component of White Ibis chick diets in the northern Everglades during both a good nesting year (6,000 nests) with higher water levels (2008) and during an excellent nesting year (9,300 nests) when water levels were lower (2009). The results from this study and an earlier study suggest fish, along with terrestrial insects and urban refuse are only secondary prey for nesting White Ibis and that wetlands with abundant crayfish populations should promote high nesting effort.