Watchers At The Pond

A new study highlights the value of ponds for birds in Delhi-NCR.

Planet Outlook
Ananda Banerjee - August 06, 2021
Watchers At The Pond

In one of Gurugram’s luxurious gated society an Indian spot-billed duck (Anas poecilorhyncha) have successfully raised two broods in the last couple of years. Resident and ace birder Kanwar B Singh posted a video on social media earlier this week saying, “Spotbilled duck has once again raised a brood at the pools of our society lawns, Gurgaon. Here, chicks taking a leisurely swim with their mother.” The scaly patterned duck sporting a distinct yellow-tipped bill with a dash of orange at the base is a stunning looking resident in wetlands across the Indian Subcontinent. To find it breeding in the greens of a high-rise residential complex is an indication of how small urban ponds are important for birds adapting to change in urban landscapes.

At the other end of Delhi-NCR, in Noida, a short walk from my residential complex leads to the neighbouring village with two small ponds. In the last three years, since I moved here, my bird checklist around the pond and the adjoining green patch stands at a modest 65 species.

 

However, ponds have become increasingly rare to find in the relentless march of urbanisation. The ones that have survived the development onslaught are in various levels of degradation. But ponds, which are now less than five percent of the capital’s geographic area  still support an incredible 37 per cent of Delhi’s bird species as revealed by a new study  ‘Capital ponds: Site-level habitat heterogeneity and management interventions at ponds regulate high landscape-scale bird diversity across a mega-city,’ by researchers Prakhar Rawal, Swati Kittur, Murali Krishna Chatakonda and K.S. Gopi Sundar from Amity Institute of Forestry and Wildlife and Nature Conservation Foundation.

Today urban Delhi and the surrounding National Capital Region (NCR) is the product of “multiple smaller urban and rural areas agglomerate into a single large urbanised landscape” with no formal incorporation of wild habitats.  The National Capital Region (Delhi- NCR) is predicted to become part of the second-most populous urban area in the world. And such large-scale urban agglomerations are the primary cause of biodiversity decline. Not just here but across the planet.

This is a study attempting to understand the effects of urbanisation on biodiversity. An area least understood in Asian and other tropical mega-cities despite these cities potentially contributing substantially to biodiversity declines because of their location - in high species diversity regions. However, standardised biodiversity surveys are missing in most urban cities in the tropics, where biodiversity levels are high alongside rapidly increasing rates of urbanisation. Delhi-NCR’s is said to have a bird checklist of over 470 species, the second-highest in the world for a metropolis. Only Nairobi, the capital of Kenya has a more impressive checklist of over 600 species.  But these checklists are drawn from rapid surveys by birders and nature enthusiasts without methodological concerns. “A large number of factors such as time of day, location of habitat, count methods and landscape structure can affect bird counts. Results of these surveys could also vary depending on how birds are grouped for analysis, including an abundance of individual species, total species richness, and composition of species spread across feeding and habitats,” says K. S. Gopi Sundar, Co-author and Scientist, Nature Conservation Foundation. Further, he added that research on birds in urban wetlands has largely been in riparian wetlands or large water bodies. Ponds have largely been neglected, though worldwide research is increasingly highlighting their potential to support a large number of taxa in varied settings.

The study states that there is no scientific assessment to see how high human population densities in mega-cities like Delhi create unique conditions for biodiversity. For example, there is no information on whether human activity at ponds changes disturbance levels for birds at different times of the day. According to the research team, the haphazard and unscientific urbanisation process can limit species persistence and composition with serious consequences for ecosystem functioning and conservation planning.

The authors argue that, “Ponds, retained for historical or cultural reasons or artificially created ponds are strong contenders for valuable remnant habitat inside cities. Ponds have the dual advantage of being manageably small while also supporting surprisingly high levels of biodiversity. These are also among the most threatened freshwater habitats, suffering degradation because of heavy human use, particularly in urban areas. These conditions have led to implicit assumptions that urban ponds have no value as habitats for wildlife.” An assumption proved wrong by the systematic surveys conducted by the team.  Between January-March 2020, a survey of 39 ponds showed the presence of 173 bird species. Moreover, ponds without any management intervention contributed the highest number of species in the survey.

The 39 ponds for the survey were chosen after scanning through high-resolution satellite images using Google Earth. The team had to review images of different seasons over the past 10 years for wetland maps in Delhi (and India) are focus on larger-sized water bodies.

This study is a first showcasing the importance of maintaining and improving erstwhile-ignored habitats such as unprotected ponds that are providing refuge to hundreds of bird species in mega-cities like Delhi. This also brings a fresh perspective to our sparse understanding of whether people and wildlife can use city spaces and remnant habitats together. 

 

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