Resource partitioning in three sympatric species of storks in Keoladeo National Park, India

Abstract

Resource partitioning in three sympatric stork species: Black-necked Stork (Ephippiorhynchus asiaticus) Painted Stork (Mycteria leucocephala) and Asian Openbill (Anastomus oscitans) ) was studied in the Keoladeo National Park, India from October 1994 to May 1997. Little is known about their feeding success in variable water depths and habitat use. The Black-necked Stork, a solitary generalist forager, uses tactile and visual methods with a high proportion offish in the diet. The Painted Stork and Asian Openbill forage in groups of two to 100. Both Painted and Asian Openbill Storks are specialists and tactile foragers, with the former preferring fish and the latter snails (Pila spp.). Differences in prey composition were mainly due to difference in feeding behavior and water level at foraging sites. Peck rate, steps and success rate varied significantly among the three species and water level influenced feeding success. The three stork species showed variations in foraging parameters in relation to fine-scale habitat use. All stork species showed preferences for foraging habitat that differed with respect to water level, vegetation community structure and the presence of prey species. The fishing depth component of resource segregation, as described in many wading bird communities has played a major role in determining feeding success and reducing niche overlap. The findings have application to foraging habitat management and the conservation of stork species.