Nest building

Avian reproduction is generally resource dependent, and resource availability can vary through time and space. Wading birds breeding activity in southern Florida wetlands is limited by availability of aquatic prey, which is largely influenced by seasonal hydrodynamics. Restoration of natural hydrologic patterns is expected to increase populations and return breeding activity in the southern Everglades, but which prey support successful breeding at coastal colonies is unknown. To address this, I examined prey use of nesting White Ibis (Eudocimus albus) at coastal colonies in Everglades National Park (ENP) in a two-year observational study. I also examined ibis diets at nesting colonies located in three regions of the Everglades to better understand regional variation in trophic support of ibis reproduction. I found that crayfish and fish were used extensively in ENP in a year with exceptional ibis breeding activity, and I provide evidence that lengthened hydroperiods in higher elevation marl prairies may enhance crayfish production and availability in the southern Everglades. I found that crayfish were the most important prey type in all regions of the Everglades when reproductive effort was highest. These results add to the growing body of evidence that crayfish are important prey for ibis reproductive success in all parts of the Everglades, and suggest that increasing water flowing into the southern Everglades may incite greater nesting at historic colony locations. With this knowledge we can forecast how wading birds, and more generally wetlands of southern Florida, will respond to a changing environment and potential restoration scenarios.

Least Terns (Sterna antillarum) have recently shifted from traditional beach nesting sites to flat gravel roofs in parts of their range. In an attempt to determine whether the thermal environment of novel roof sites contributes to nesting success relative to that of traditional sites, hatching and fledging success and fifteen possible thermoregulatory behaviors of roof-nesting Least Terns were examined at four sites in Palm Beach County, Florida in 1992. The mean numbers of chicks and fledglings produced/nest (1.13 and 0.70, respectively) were significantly higher than those reported in other recent studies, indicating that nesting on some roofs is successful and may be a good alternative to beach locations. There was no difference between equivalent temperatures at the roofs and at a nearby beach, thereby suggesting that the new thermal environments of roofs do not adversely influence hatching and fledging success in Least Terns.