Foraging Guild Structure and Niche Characteristics of Waterbirds in Pong Wetland, Himachal Pradesh

Abstract

Wetlands are one of the important habitats for waterbirds, yet the mechanism of niche segregation among the waterbird communities is understudied. This study focused on the foraging guild structure and niche characteristics of waterbirds in Pong wetland during the wintering season. The study takes into account foraging habitat (water depth, secchi depth and vegetation type) and foraging technique used by the waterbird species to understand resource partition and coexistence. The study was carried out from December 2024 to March 2025 using the point count method in two different sites of the Pong wetland i.e., Meenu khad and Gaj khad each having five replicates. The total sampling effort was 56 days with 26 days in Meenu khad and 30 days in Gaj khad. The species richness analysis of both the sites revealed Meenu khad to be more species rich than Gaj khad likely due to variation in water depth in the region, resulting in different habitat conditions. The monthly abundance of waterbirds in Pong wetland was found to be at its peak in the month of January. Generalist species such as the Eurasian Coot and Tufted Duck occupied the broadest habitat and combined niche breadth than that of specialists such as the River Tern. Furthermore, in terms of extensive foraging strategy, species such as the Northern Shoveler and Intermediate Egret occupied broader niche breadth, demonstrating behavioral flexibility in resource acquisition. The clustering of waterbird communities resulted in four functional guilds that are responsible for reducing competition and allowing species coexistence. It was found that the intraguild overlap was significantly higher than the interguild overlap (F = 54.34, p < 0.001). The null models further showed the mechanism that could be responsible for structuring the communities. It resulted in higher observed niche overlap than expected, signifying that community structure of waterbirds is largely influenced by morphological variations leading to different foraging habits, variable abundance of waterbird species and presence of abundant resources at Pong Dam. This study is the first in providing deeper understanding on seasonal waterbird abundance, niche requirements and community structure at Pong Lake. This study serves as a baseline to continue future studies in the region and assess the impacts of changing land use practices as well as changing climate on species occurrence and abundance and community structure. Furthermore, the study also showed the region to be an important staging ground for many migratory species, therefore, focusing on targeted habitat management will be crucial to support the diversity of waterbird species.are one of the important habitats for waterbirds, yet the mechanism of niche segregation among the waterbird communities is understudied. This study focused on the foraging guild structure and niche characteristics of waterbirds in Pong wetland during the wintering season. The study takes into account foraging habitat (water depth, secchi depth and vegetation type) and foraging technique used by the waterbird species to understand resource partition and coexistence. The study was carried out from December 2024 to March 2025 using the point count method in two different sites of the Pong wetland i.e., Meenu khad and Gaj khad each having five replicates. The total sampling effort was 56 days with 26 days in Meenu khad and 30 days in Gaj khad. The species richness analysis of both the sites revealed Meenu khad to be more species rich than Gaj khad likely due to variation in water depth in the region, resulting in different habitat conditions. The monthly abundance of waterbirds in Pong wetland was found to be at its peak in the month of January. Generalist species such as the Eurasian Coot and Tufted Duck occupied the broadest habitat and combined niche breadth than that of specialists such as the River Tern. Furthermore, in terms of extensive foraging strategy, species such as the Northern Shoveler and Intermediate Egret occupied broader niche breadth, demonstrating behavioral flexibility in resource acquisition. The clustering of waterbird communities resulted in four functional guilds that are responsible for reducing competition and allowing species coexistence. It was found that the intraguild overlap was significantly higher than the interguild overlap (F = 54.34, p < 0.001). The null models further showed the mechanism that could be responsible for structuring the communities. It resulted in higher observed niche overlap than expected, signifying that community structure of waterbirds is largely influenced by morphological variations leading to different foraging habits, variable abundance of waterbird species and presence of abundant resources at Pong Dam. This study is the first in providing deeper understanding on seasonal waterbird abundance, niche requirements and community structure at Pong Lake. This study serves as a baseline to continue future studies in the region and assess the impacts of changing land use practices as well as changing climate on species occurrence and abundance and community structure. Furthermore, the study also showed the region to be an important staging ground for many migratory species, therefore, focusing on targeted habitat management will be crucial to support the diversity of waterbird species.