Adaptability of Wetland Birds to Changing Landscapes

Himanshu Choudhery

The advent of the industrial revolution paved the way for massive industries and settlements to be set up in new areas, that we now call cities and towns. Due to this, a large number of people from rural areas have settled down in cities in search for employment and a ‘better life’. As a consequence, the population in these areas is rapidly growing, due to which there is little space left for natural forests and water bodies. In Delhi and its peripheral areas, some important water bodies exist which are home to a number of avifaunal species. Although increasing urbanization has led to the disappearance of several species of birds from urban waterbodies, there are other species that continue to adapt to changing conditions of these waterbodies.

One such species is the Gray-headed Swamphen (Porphyrio poliocephalus) which is an urban adapter. Urban adapters are those species that can utilize both urban and rural habitats and have the capability to thrive in a disturbed habitat in the absence of natural habitat. The Gray-headed Swamphen is a resident bird in India and belongs to the Rallidae family. It can be easily identified by its bluish-purple body and red bill. It mostly utilizes marshy areas of wetlands, although, in rural areas, it can also be seen using agricultural land. Most often, the Gray-headed Swamphen forages in groups on a specific part of the wetland where water hyacinth (Eichhornia) and reeds are prominent. Group foraging, as opposed to solitary foraging, is an advantageous social behavior as it makes the species less vulnerable to predation.

Image 1: Gray-headed Swamphen (Porphyrio poliocephalus) standing on water hyacinth. Photo Credit: Shashank Bhardwaj

Most wetlands in Delhi and its peripheral areas harbour significant numbers of Gray-headed Swamphen. Below is a map of the distribution of the species in and around Delhi, and is indicative of how well adapted the species is in the urbanized landscape.

Figure: Map showing the distribution of the Gray-headed Swamphen in Delhi and its surrounding areas. Source: eBird

There are various factors which influence the adaptation of birds to a particular place, for instance, food, nesting site, response to changing environment, and so on. While a species like the Gray-headed Swamphen has managed to thrive in the urban environs of the national capital, there are other wetland-dependent species like the Oriental darter (Anhinga melanogaster), Sarus crane (Grus antigone), and Woolly-necked stork (Ciconia episcopus) which are rarely seen in Delhi due to deteriorating waterbodies and absence of good quality natural habitat. These species are not acclimated to the changes that are swiftly occurring in the urban environment, and are either maintaining a low profile in these substandard environments or are completely migrating to other less urbanized areas.

In order to create conducive conditions in the urban environment for the sustenance of different bird species, including those dependent on wetlands, it is very important to understand the life-histories and movement patterns, of both, species that have been successful in the urban, as well as those that have failed to acclimatise to the changing nature of urban habitats. Such insights will help in the conservation of avifaunal species in the urban environment, especially those that face the risk of becoming threatened or extinct in the near future. Also, in recent times, the generation of citizen science data has been considered to be very helpful in conservation programmes of birds. If people can contribute more actively through such initiatives, the task of assessing population status and threat to bird species can be made quicker and more efficient.

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