FORAGING ECOLOGY OF SEVEN SPECIES OF NEOTROPICAL IBISES (THRESKIORNITHIDae) DURING THE DRY SEASON IN THE LLANOS OF VENEZUELA

sympatric species of ibises (Threskiomithidae) in the Venezuelan llanos during the dry season of 1989. Scarlet (Eudocimus ruber), Glossy (Plegadis falcinellus), and Bare-faced (Phimosus infiscatus) ibises were the most common species. White (E. albus), Green (Mesembrinibis cayennensis), Sharp-tailed (Cercibis oxycerca), and Buff-necked( Theristicus caudatus) ibises together made up less than 8% of individuals surveyed. Multivariate analyses showed that differences in use of foraging habitat partitioned the foraging niche during the dry season, a time when little aquatic habitat is available to the birds. Foraging habitats used by the seven species were differentiated by decreasing distance to water, in the following order: Buff-necked (dry land), Sharp-tailed and Bare-faced (moist soil, occasionally in standing water), Green (water’s edge), and Scarlet, White, and Glossy ibises (nearly always in standing water). Probing depth, prey size, and height of vegetation further partitioned the niche. Large differences in capture, probing, and stepping rates were found among all species.

PETER C. FREDERICK AND KEITH L. BILDSTEIN, Wilson Bull., 104(l), 1992, pp. 1-21