Spatial, temporal and trophic resource partitioning among the four egret species (Aves: Pelecaniformes: Ardeidae) in a tropical wetland ecosystem, India

Abstract

The diversity of micro-habitats in tropical wetlands allows the coexistence of several species. These sympatric species interact with each other, either directly or indirectly, to optimally use the available resources. They achieve this through niche separation or minimal overlap to avoid competition. India’s wetland ecosystems are home to various sympatric species, such as the Great Egret Ardea alba (GE), Median Egret Ardea intermedia (IE), Little Egret Egretta garzetta (LE) and Cattle Egret Bubulcus ibis (CE). These egret species are closely related, and as a result, have similar niche requirements, which could lead to high intra-specific competition. However, there have been few studies on how these species utilize resources. This study aims to understand the possible mechanisms that enable the coexistence of these species in a tropical wetland. We have examined habitat characteristics, feeding behaviour, timings of seasonal and daily activities, and spacing patterns to evaluate possible models of species coexistence. We discovered that these four sympatric egret species have differences in microhabitat selection, activity patterns, both daily and seasonally, and feeding preferences. The study further indicates that there is a relationship between the niche dimensions, but it is only partially dependent on each other.