Decline of Wading Birds in Southern India

January 9, 2025

Coastal and inland wetlands in southern India are experiencing decline. A recent study conducted in Kerala has revealed alarming trends in the population of wading birds, which serve as crucial indicators of wetland health. The research spans the decade from 2010 to 2019, denoting the impact of anthropogenic changes on these vital ecosystems.

Study Overview

The study involved a comprehensive analysis of 27 sites, including estuaries, beaches, mudflats, mangroves, and agro-ecosystems along the Kerala coast. Key locations included Azheekkal estuary, Ayikkara beach, and Kayamkulam estuary. Researchers monitored environmental variables such as climatic conditions, sediment composition, water quality, and fish stock availability to assess their effects on wading bird populations.

Key Findings on Wading Bird Populations

The researchers focused on six common wader species – Great Egret, Median Egret, Little Egret, Indian Pond Heron, Western Reef Egret, and Black Headed Ibis. The study found decline in the densities of all species over the study period. Seasonal variations were evident, with higher densities recorded during post-monsoon seasons compared to lower numbers during monsoons.

Environmental Changes Impacting Waders

The study identified several environmental factors contributing to the decline in wading bird populations. Increased salinity, pH, and temperature levels were noted in both water and sediment. Conversely, organic carbon and nitrogen levels in sediments decreased . These changes adversely affected primary productivity and fish stock availability, crucial for the survival of large waders.

Adaptation and Habitat Shift

In response to declining wetland health, wading birds have adapted by shifting their foraging habits to agroecosystems and estuaries. The study indicates that as their natural habitats deteriorate, these birds are forced to seek alternative environments for food. This behavioural shift raises concerns about the long-term viability of wading bird populations in the region.

Great Egret is also known as Ardea alba.
Median Egret is scientifically named Ardea intermedia.
Indian Pond Heron is referred to as Ardeola grayii.
Western Reef Egret is called Egretta gularis.
Black Headed Ibis is known as Threskiornis melanocephalus.

Recommendations for Ecosystem Restoration

The researchers emphasised the urgent need for strategies to mitigate the adverse effects on wetland ecosystems. They advocate for comprehensive restoration efforts to improve ecosystem health and support the recovery of wading bird populations. Enhanced monitoring and management of environmental variables are critical to reversing the current trends observed in these vital habitats.

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