The search for India's hidden treasures
Come for the rhinos, stay for the birds – that should be the motto of Assam’s tourist board. Every year, thousands of visitors flock to the remote north-eastern Indian state in the hope of catching a glimpse of the rare Indian rhinoceros Rhinoceros unicornis, which has less than 3,000 surviving individuals left in the world, roughly two thirds of which are found in Assam’s spectacular national parks.
But the region is also a birding hotspot. Two of the state’s parks, Kaziranga and Orang,are recognised by BirdLife as Important Bird & Biodiversity Areas (IBAs), with 512 and 225 identified species of bird respectively. Tourists don’t even need to take their eyes off the rhinos to drink in the rich avifauna; egrets and mynas can often be seen hitching a ride on their backs, feasting on the parasites that live in the folds of their skin or feeding on insects disturbed by these behemoths.
Birdwatchers who look further afield to the parks’ rivers and forests might encounter much rarer species of bird, such as the Critically Endangered White-bellied Heron Ardea insignis or the Near Threatened Great Hornbill Buceros bicornis. But while Assam’s forest environments are well-protected by Indian law, the surrounding grassland and wetland areas often go neglected.
These thick, almost impenetrable fortresses of grass and reed are home to numerous globally-threatened bird species, the most iconic of which is the Bengal Florican Houbaropsis bengalensis, a Critically Endangered bustard that, aside from a small population in Cambodia, exists only in isolated populations across the grasslands of northern India and Nepal. Despite the lack of attention they receive, the future of these environments is threatened by numerous factors.
Grasslands on the Brahmaputra. © Dhritiman Mukherjee
They are becoming increasingly fragmented as they are cleared for agriculture and settlements, while grass burning, performed to make the land more suitable for the needs of large mammals, can destroy nests and eggs of grassland birds. Since most of these areas are rarely visited by birdwatchers, both for logistical and safety reasons (there are rhinos and tigers on the loose in these parks, after all!), the true status and range of the bird species that are dependent on these grasslands were not well understood – until now.
To fill this gap in our knowledge, a team from Bombay Natural History Society (BNHS, BirdLife in India), led by Senior Scientific Adviser Asad Rahmani, embarked on a one year project to survey the tropical grasslands that extend across the floodplains of the Brahmaputra, a major river that originates on the Tibetan Plateau, flows westwards through Assam and snakes southwards towards Bangladesh.
“I have been going to Assam for the last 30 years to survey and study Bengal Florican” says Rahmani. “During these surveys I found that floodplain grasslands are rather limited, and so are the species which are obligate to these grasslands. I had written proposals and encouraged others also to work on grassland species, but unfortunately no-one in India was interested in funding these projects. Then, two years ago, BirdLife International helped us by securing funds through their Preventing Extinctions Programme, allowing the study to go ahead.”
The project covered an area of grassland around the Brahmaputra, ranging from the lowlands of Arunachal Pradesh state in the north of the country to the plains of Assam. A wealth of protected areas can be found on the river’s floodplains; in addition to Kaziranga and Orang, the team visited numerous smaller or lesser-known wildlife sanctuaries such as Pabitora, as well as numerous non-protected grasslands, many of which were over-run by grazing cattle.
Also included in the survey were areas that fell outside the boundaries of the floodplain, but contained important grasslands where some of the species targeted by the study have been sighted. The largest of these being Manas National Park, a 520 km2 elephant and tiger reserve on the Bhutanese border, nearly half of which is covered in tall grass known to host species such as Jerdon's Babbler Chrysomma altirostre, Swamp Prinia Laticilla cinerascens (a sub-species of the Rufous-vented Prinia set to be recognised as a distinct species in the 2016 IUCN Red List), and Black-breasted Parrotbill Paradoxornis flavirostris.
Watching for birds in Orang National Park's untamed grasslands. © Asad Rahmani
All three of these species have something in common: they are small, sedentary birds that like to skulk and forage in tall, dense grass, which can reach as high as three to five metres in some areas. “That is why it is known as elephant grass”, says Rahmani. “It hides even an elephant.” Due to the rich soil and frequent rainfall, the grass grows back rapidly, clogging up walking trails in a matter of days if they are not used. This makes it an arduous environment to navigate by foot, and also caused the team a more pressing problem – in the thick blanket of grass, it is extremely difficult to locate these secretive birds unaided.
One of the techniques the team used to overcome the difficulty of surveying in this habitat was tape playback. After selecting which species’ calls to play in accordance to the length and type of grasses in each area, the calls were played either until the species was detected, or ten minutes elapsed, after which they would move on to a new spot, no less than 100 metres away, and begin the process again, marking their location and findings via a GPS log each time.
Playback is most effective during the breeding season when the birds are more vocal, which for many species falls between February-May, meaning the team had a very short window to conduct their studies. Other species breed during the monsoon season (June-September), during which time most of the national parks are closed. Indeed, the team was only able to conduct field work during November-May, as seasonal flooding rendered the majority of the grasslands inaccessible. While many species reacted well to tape playback, there were other species of interest, including the Bengal Florican, which cannot be lured by the technique, so the team had to depend on visual sightings only.
But even in fair weather, the remoteness of the area resulted in numerous logistical nightmares for the project. Many of the suitable grassland habitats were located on uninhabited islands, orchaporis, on the Brahmaputra River. And within many of the major national parks, the team were unable to survey many of the grasslands on foot for the same reason birdwatchers can’t – the presence of large mammals such as rhino. Even in non-protected grasslands, where rhinos aren’t found, the team faced danger in the form of feral wild buffalo and wild pigs.
Jerdon's Babbler © Ranjan Kumar Das
Despite these tribulations, Rahmani’s team were able to compile a preliminary report that greatly enriches our understanding of the population status and distribution of the 12 globally threatened grassland species targeted in the survey. The findings indicated that the plight of many of these birds may be worse than even the team suspected. The endemic Manipur Bush-quail Perdicula manipurensis is of particular concern. Little is known about the ecology and behaviour of this shy ground bird; it is believed that the degradation and fragmentation of its grassland habitat has resulted in the species’ decline. The team did not encounter the quail during their field work, nor during separate surveys in 2015 and 2016. It was recently uplisted to Endangered on the IUCN Red List in 2013, but with only two confirmed sightings in the last 50 years, Rahmani suggests it could now be further elevated to Critically Endangered. The report recommends a follow-up survey that extends the search from West Bengal to Manipur, using elephants for survey in areas where flushing the birds out on foot is not possible. While the Manipur Bush-quail was already known to be scarce, other findings illustrate exactly why this research was necessary.
The Swamp Prinia, an unassuming olive-grey wren-warbler, was assumed to be widespread, but the findings reveal that its range is far more restricted than was first thought. The report recommends further studies such as ringing and colour marking, so we can further study their movements, in addition to the recreation of suitable habitats in areas where the bird was once present, but now has apparently vanished. Similar measures are recommended for the Black-breasted Parrotbill, which is now found only in five locations, and is threatened by the fragmentation of the grasslands caused by local villagers cutting the grasses down for thatch, furniture and fencing.
Many of the grasslands explored were on remote, uninhabited islands. © Asad Rahmani
Better news comes in the form of several relatively stable populations of Bengal Florican in Kazaringa, Orang and Manas, but its future is still threatened on several fronts. Threats include the constructions of dams upstream in Arunachal, which will affect the flow of the river in as-yet unknown ways, and the conversion of grassland outside of protected areas into agricultural land. Within some protected areas, such as D’Ering Wildlife Sanctuary in Arunachal Pradesh, habitats are threatened by the spread of big-sage Lantana camera, an invasive weed from Central America which aggressively out-competes local plants. Elsewhere in the region, Kaziranga is plagued by the thorny Brazilian species Mimosa diplotricha, which forms impenetrable thickets, while the spread of wild rose Rosa spp. is damaging swampland and reducing plant biodiversity.
Combating invasive plant species in these areas is particularly challenging due to the nature of the land. “As many areas have rhino, elephant and wild buffalo, ground work has to be done under armed guards. We cannot depend on volunteers to go around removing these invasive weeds”, says Rahmani. Outside of protected areas, Rahmani adds, the grasslands studied have little future unless urgent action is taken. The majority have been degraded by overgrazing, or from badly-managed burning, which occasionally spirals out of control, torching everything in its path.
Happily, the team discovered there is still plenty of good grassland habitats within the protected areas that, if properly cared for, can continue to support Assam’s grassland specialists. The next step is to influence local users to alter the ways the grasslands are managed to allow for more bird-friendly practices. This is a complex task, with many social and legal issues.
This seminal study was made possible by generous support provided by BirdLife Species Champion Per Undeland, through The BirdLife Fund for the Conservation of Threatened Indian Birds– a BirdLife Preventing Extinctions Programme initiative. The data gathered on the threatened species during the course of this study will prove invaluable in helping to secure their futures, but the greatest long-term impact may come from the team’s work in networking with local communities, researchers and decision makers, in the process of raising awareness of the importance of grassland conservation. “In Assam, most management practices are tuned to look at the needs of large glamorous species such as tiger, elephant, rhino, swamp deer, wild buffalo”, says Rahmani. “We have to bring a paradigm shift in this thinking.”