title: Patterns of resource partitioning by nesting herons and ibis: how are odonata exploited?
abstract: Herons and ibis are colonially nesting waders which, owing to their number, mobility and trophic role as top predators, play a key role in aquatic ecosystems. They are also good biological models to investigate interspecific competition between sympatric species and predation; two processes which structure ecological communities. Odonata are also numerous, diverse, mobile and can play an important role in aquatic ecosystems by serving as prey for herons and ibis. A relationship between prey size and bird predator has been observed in Numidia wetlands (NE Algeria) after analyzing food boluses regurgitated by six species of birds (Purple Heron, Black-crowned Night Heron, Glossy Ibis, Little Egret, Squacco Heron and Cattle Egret) during the breeding period, which also shows a temporal gradient for the six species. Both the Levins index and preliminary multivariate analysis of the Odonata as prey fed to nestling herons and ibis, indicated a high degree of resource overlap. However, a distinction of prey based on taxonomy (suborder and family) and developmental stage (larvae or adults) reveals a clear size dichotomy with large-sized predators (Purple Heron, Black-crowned Night Heron and Glossy Ibis) preying on large preys like Aeshnids and Libellulids and small-sized predators feeding mainly on small prey like Zygoptera. Overall, the resource utilization suggests a pattern of resource segregation by coexisting nesting herons and ibis based on the timing of reproduction, prey types, prey size and foraging microhabitats.
authors.affiliation: Laboratoire de recherche et de conservation des zones humides, University of Guelma, Guelma, Algeria. bsamraoui@yahoo.fr
authors.forename: Farrah
authors.initials: F
authors.lastname: Samraoui
authors.forename: Riad
authors.initials: R
authors.lastname: Nedjah
authors.forename: Abdennour
authors.initials: A
authors.lastname: Boucheker
authors.forename: Ahmed H
authors.initials: AH
authors.lastname: Alfarhan
authors.forename: Boudjéma
authors.initials: B
authors.lastname: Samraoui
mesh_terms: D000462:Algeria; D000465:Algorithms; D000818:Animals; D001717:Birds / Q000502:physiology*; D003627:Data Interpretation, Statistical; D004032:Diet; D017753:Ecosystem; D005247:Feeding Behavior / Q000502:physiology; D007313:Insecta; D007814:Larva; D015999:Multivariate Analysis; D009425:Nesting Behavior / Q000502:physiology; D011235:Predatory Behavior / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology; D013045:Species Specificity; D061350:Sympatry; D053833:Wetlands