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ABSTRACT: In 1999, we compared foraging success rates (captures/min) and foraging behaviors of Wood Storks (Mycteria americana) at tidal (Georgia) and non-tidal freshwater (South Carolina) foraging sites. Foraging success rates were 30 times greater at the tidal site, but storks foraging in tidal areas only fed at low tide, which limited their foraging time at that site. On-site behaviors indicated the window of prey availability. Storks at the tidal site engaged almost exclusively in foraging behaviors, whereas storks at the non-tidal site devoted more time to other, non-foraging behaviors (e.g., preening, resting). The greater foraging success rate associated with the tidal site suggests that salt marsh/tidal creek habitats are high quality foraging areas. Wading birds use a diversity of behaviors to acquire prey. Wood Storks (Mycteria amer-icana) feed mostly by tactilocation, literally bumping into their prey with partially open bills and capturing prey with a rapid reflex action (Kahl and Peacock 1963). They also employ a repertoire of associated behaviors (e.g., foot stirring, wing flashing) for startling prey or otherwise making them more active and possibly more catchable (Kushlan 1978). To forage effectively, Wood Storks require shallow wetlands with concentrations of prey (Kahl 1964). Non-tidal freshwater foraging habitats in Georgia are typically shallow, rel-atively free of vegetation, non-flowing, and support prey densities ranging from 0.1 to 50.0 prey items/m 2 (mean 7.8 prey/m 2 ; Coulter and Bryan 1993). The use of tidal salt marshes by foraging storks has also been doc-umented during both breeding and non-breed-ing seasons, and it is presumed that tidal creeks draining as the tide recedes (2.5 m tidal amplitude in Georgia) provide excellent con-ditions for foraging storks (Gaines et al. 1998, Bryan et al. 2002). To test this presumption, we observed storks within tidal and freshwater non-tidal foraging habitats in 1999 to compare foraging success rates and behaviors. The Wood Stork was federally listed as an endan-gered species in 1984 due to population
The Wilson Bulletin 01/2005; 117(4):386-289. · 0.66 Impact Factor
