Nesting White Ibis prey use in Everglades National Park in 2017 and 2018

As avian reproductive success is generally prey limited, identifying important prey types or sizes, and understanding mechanisms governing prey availability are important objectives for avian conservation ecology. Irruptive White Ibis (Eudocimus albus) nesting at coastal colonies in the southern Everglades numbered over 100,000 nests in the 1930s. A century of drainage and altered hydrologic patterns reduced aquatic prey availability and eliminated large nesting events; nesting activity in recent decades has been typically <5% of historical peaks. Hydrologic restoration is expected to increase ibis nesting activity, but which prey types will support high nesting effort is less clear. In 2017 and 2018 we collected food boluses from White Ibis chicks at coastal colonies in Everglades National Park. We also monitored regional nesting activity from 1999-2018. In 2017 the region had 1,075 nests, typical of the past several decades, but in 2018 there were 30,420 nests, representing the hig...