... do conditions change for waterbirds?
The north Indian landscape is changing rapidly. Expanding agriculture and urban development are two common issues that garner attention. In this project, we explore how illegal conversion of community wetlands to fish ponds has taken root in Palwal district, Haryana, and assess how waterbirds are being affected.
Northern-Indian croplands: a landscape of change
North Indian croplands are varied in their age, some experiencing high-intensity use for over 10,000 years. They support 3-5 crops each year, and form the backbone of the rural economy that millions of farmers depend on. These landscapes, at first glance, appear to be monotonous expanses of crops, and nothing more. In fact, these are very complex mosaics that include thousands of freshwater wetlands, trees, grassland patches, uncultivated lands, all surrounding small villages and towns where people concentrate.
In and around the capital New Delhi, these landscapes are being looked at as areas that require industrial and urban development in anticipation of future needs. Vast areas of fertile agriculture are being converted to Special Economic Zones, and are being taken over for new townships and roads. These changes have been relatively easy to follow using satellite images. The conversions of wetlands, many of which are tiny in size, has been much less easy to follow.
In this study, we evaluate the wetlands of one district in Haryana state - Palwal. This district is within the newly declared "National Capital Region" - an area marked for development, but also important for Sarus Cranes. We assess the persistence of wetlands in Palwal over two time periods (1970s and 2000s). We also check to see if management styles of these wetlands have changed in the recent past. Finally, we check to see what these changes have meant to waterbirds that continue to use these wetlands.
Mapping wetlands and assessing waterbird use
Carefully developed wetland maps are woefully rare in India. We decided to develop such maps for Palwal using the excellent and high-resolution 1:50,000 topographic maps developed by the Survey of India. We procured topo-maps for the 1970s, and also for the 2000s, and digitized all the wetlands for both time periods. Developing maps from two time periods was necessary to ascertain the level of wetland persistence in Palwal. We then calculated the area of each wetland from both time periods, and carefully checked which wetlands were still existing. If not, we determined the reason for their disappearance.
Wetlands were not distributed equally in the 2000s (see (d & e) in the figure below). We therefore decided to overlay the district with a 10x10 km grid, and choose wetlands for our waterbird study from all the grids equally. This method helps overcome potential biases in waterbird distribution due to different densities of wetlands. We also decided to check if waterbirds in Palwal used wetlands differently depending on where these are located - in towns or amid cultivation. This was an important additional aspect to include since the importance of wetlands in towns to waterbirds is as yet unexplored in India. We chose the largest "town wetland" and the largest "agricultural wetland" in each grid in which to carry out counts of waterbirds (see (f) in the figure below). We then carried out counts of 31 waterbird species in these chosen wetlands.
What happened to Palwal's wetlands
In the 1970s, Palwal had 720 wetlands spread over 1,333.5 ha. In the 2000s, the extent of wetlands reduced by 52.6% to 701.3 ha. The average size of individual wetlands also reduced by 43% during this period from 1.85 ha (10 ha SD) to 0.8 ha (2 ha SD). Palwal lost 151 wetlands to agricultural expansion, and 93 wetlands to expansions of towns between the 1970s and 2000s. Most of the loss of the acreage of wetlands was, therefore, due to loss of agricultural wetlands (see (a, c & e) in the figure below).
The total number of wetlands, however, increased to 875 in the 2000s (see (b, d & f) in the figure below). Twenty-three of the existing wetlands were cut up into 56 smaller wetlands, and 366 completely new, but tiny, wetlands were added on the landscape. This increase in wetlands was led by a complete change in management practices - Palwal's wetlands stopped being common use areas, and changed almost entirely to private fish ponds! This crucial change seems to have necessitated reducing the wetlands' size to manageable units for pisciculture.
Waterbird use of Palwal's wetlands
Taking into account all 31 focal waterbird species, the bird composition in town and agricultural wetlands was identical. Such a landscape-scale homogenization is indicative of habitat stress: there are likely too few wetlands already for waterbirds in the Palwal area. However, 20 species had higher numbers recorded in agricultural wetlands. These included large species such as Painted Storks, Woolly-necked Storks and Red-naped Ibis, and smaller species such as Black-winged Stilts, White-tailed Lapwings and Common Kingfishers. Only three species - Common Coot, Little Egret and Great Cormorant - were found more in town wetlands. More seriously, three waterbird species of conservation concern - the Sarus Crane, the Black-necked Stork, and the Eurasian Spoonbill - were found only in one wetland during the surveys.
During the surveys, we observed that people continued to use wetlands converted to fish ponds for various purposes. We listed uses at each wetland, and measured vegetation cover along the shore, to check which of these factors affected waterbird numbers relative to location of wetlands. Wetland location contributed <20% to observed differences in bird counts (see figure below). Vegetation cover had been greatly reduced at sites, and had a very small effect (<10%) on bird numbers. Bird numbers were affected most by human uses of wetlands: removal of water for agriculture (which likely restored original shallow conditions), and addition of sewage.
Changing management, changing conditions
The nearly whole-scale conversion of wetlands in Palwal from community use, open-access areas to private fish ponds had gone undetected. This change is illegal in wetlands that were officially community use lands. This change has also been responsible for the reduction of the total wetland area in the district. When wetlands are altered to make way for fish culture, the banks are raised, nearly all of the vegetation is removed, and fish species that are not necessarily native are added in large numbers. Conversion of wetlands to fish ponds therefore leads to a reduction of habitat to a very large number of wetland flora and fauna. This is already visible in terms of some of the large waterbirds, that occur in much large numbers in the community use wetlands of neighbouring Uttar Pradesh. In Uttar Pradesh, the Sarus Crane was one of the commonly occurring waterbird species in wetlands, and increased in numbers as size of wetlands increased. In Palwal, despite our focus on the largest wetlands, Sarus were seen in only one wetland!
The loss of wetland area in Palwal is a very serious concern. Ecological values of wetlands such as flood control and groundwater recharge have likely been reduced greatly. An increase in extreme rainfall events is predicted due to global climate changes; effects of these extremes will now likely be exacerbated in areas like Palwal affecting both wetland diversity and farmers. Preventing such rapid changes and conserving wetlands is urgent and crucial!
Research, laws and policy
Research on wetland biodiversity, an understanding of ongoing changes in management regimes in wetlands, and development of meaningful policy is, unfortunately, rare in India. In some areas, research is underscoring how human use of community wetlands does not necessarily lead to their decline as bird habitat. However, detailed understanding on what human uses are "good", and to what species, is missing.
Conversion of wetlands to fish ponds, despite being illegal, is clearly very widespread in some areas like Palwal. Monitoring and research attention to unprotected, freshwater wetlands in India can help raise awareness of such illegalities, and also highlight how they impact important ecosystem functions such as providing habitat to biodiversity.
Laws and policies for wetland conservation are being gradually developed in India. Previously labelled "wastelands", there is now widespread awareness of the importance of wetlands. Most of the information on wetland ecology is from temperate countries, and there is exceedingly limited information with which to frame meaningful policy in sub-tropical and tropical countries like India. The number of papers providing primary information on the ecology of Indian wetlands are still few and far between, while generic reviews are on the rise. This irony requires correction to enable more realistic policy that can take into account socio-ecological realities governing Indian wetlands.
This research was conducted in close collaboration with the Ambedkar University, New Delhi (AUD). We thank Dr. Suresh Babu for facilitating this work as part of Aditya's Masters Thesis project. We also thank several other colleagues at AUD for administrative support to Aditya and discussions. All photographs used in this article are by Aditya Singh Chauhan.