Here Comes the Drone

Field notes from Bihar, 2023.

As the sun set after another day of fieldwork, we returned to our accommodations. I recounted the day's events while transferring media. We spent the morning in the field, followed by a quick lunch, and then returned to the field. Later in the evening, we prepared for an upcoming workshop with the forest department. Our days in sunny Bihar this February had been exciting.

Our day was indeed full of action, conducting aerial transects to estimate gharials at our field sites along the riverbanks of the Gandak. We scanned the waters intently, hoping to catch a glimpse of life beneath the surface. The splashes and movements in the water kept us on edge, wondering if it was a dolphin or something else entirely. Moving to another site on the north bank, we got started on our drone transects, and that's when things took an unexpected turn – a buffalo nearly charged us! The adrenaline rush was real, but we pushed through, even laughing, completing our tasks and moving on to another location to observe dolphins. During our time on this site, we counted four gharials and a solitary dolphin, while also spotting an enigmatic stork.

Evading a curious buffalo on field-site.

After wrapping up our fieldwork, we returned to charge our drones and have a quick lunch. Our tasks for the day weren't done yet – we were headed to another site near our accommodations for mapping and conducting bathymetry tests soon after. Bathymetry tests involve measuring the depth of water bodies, in this case, of the river. By initiating the flying of the drones over the same river channel, our objective was to ascertain whether RGB drones could provide any information regarding the river’s bathymetry.

Once the media we had gathered were transferred, we set off for our next site. Though the plan didn't unfold exactly as anticipated, the unexpected offered new opportunities. The survey boat was unable to go around the sandbar as intended. Instead, we flew the drone following the boat's path to take pictures at frequent intervals along the same route. This was a way to conduct simultaneous surveys using two different techniques: not only exploring the presence of dolphins but also comparing methods used.

Survey boat as seen from the aerial drone.

The integration of drone technology has repeatedly demonstrated its potential in conservation efforts. Drones' capabilities to swiftly and comprehensively survey areas can reshape how researchers and conservationists approach their work. High-resolution imagery captured by drones works to bridge the gap between traditional survey methods and modern technology, enhancing data accuracy and efficiency. For those of us fortunate enough to witness the impact of drones on conservation firsthand, tangible feelings of excitement and curiosity emerge.

It was during this flight that the true excitement around drones became evident. As the drone took to the sky, a group of children gathered around, captivated by the spectacle. Their excitement was contagious, as they curiously identified the drone and spun imaginative stories about its purpose, whilst mistaking my hand-held camera for a CCTV! In a sense these robotic ‘toys’ facilitated a more accessible dialogue about wildlife.

Children taking turns viewing from a pair of binoculars, whilst the project team conducts a mapping mission from the banks of the river.

The stunning illustrations of local wildlife prepared by the GCA and Madras Crocodile Bank shared by Tarun Nair as part of his presentation to the forest department.

The evening was one of light chatter and marvelling at the rich diversity of this region. A glimpse of the stunning illustrations of local wildlife, compiled by Tarun Nair as part of his presentation to the forest department, served as a reminder of the beauty we were working to protect.

The excitement and curiosity surrounding drone technology for conservation are undeniable. With each passing day, more researchers and conservationists turn to drones, gaining insights into our natural world. Being a part of this field is a privilege, and I'm excited about the future and the positive impact drones can have on conservation.

From Drones to Dolphins

Nandini’s eyes light up every time she spots a dolphin surface on the screen. The mobile screen displaying the live feed from the drone currently hovering above the river’s surface - recording a pod of feeding Ganges river dolphins. Metres away from the shallow pool lies a gharial, India’s rarest crocodilian, basking in the evening sun on a sandbar. The team and I are currently on the banks of the river Gandak, a tributary of the river Ganga that flows through West Champaran district of Bihar. We are nearing the end of the day and the first of two field trips to develop systems for conservation and monitoring endangered river dolphins and gharials in regulated rivers of India’s Gangetic plains.

Drone pilot Nandini Mehrotra (centre) monitoring dolphin behaviour through the drone’s controller.

Ganges river dolphins (GRDs), as their name suggests are endemic to the Indo-Gangetic Basin. They are frequently spotted alone or in small groups, and typically a mother and calf travel together.¹ They are essentially blind hunters who use ultrasonic sound waves to detect fish and other prey.² Like most cetaceans, GRDs spend much of their time underwater, surfacing briefly to breathe.³ The movement of these animals is now known from observation to follow seasonal patterns, moving upstream when the water level rises before entering smaller streams. Due to the same —short glimpses of their presence above water and an inability to record their presence underneath because of turbid conditions that make camera entrapment impossible—monitoring their presence and mobility is difficult.

Historically, the rivers of Bangladesh, Bhutan, India, Myanmar, Nepal, and Pakistan were all included in the gharial’s habitat range.⁴ Today, its range is restricted to a few big rivers in India, Nepal, and Bhutan. It is easily identified from other crocodiles because of the adult male’s long and slender snout resembling the Ghara (a type of earthen pot used for storing drinking water).⁴ The gharial, a keystone species for the health of freshwater systems, works as do other crocodile species to move nutrients from the riverbed to the surface, boosting fish populations and assisting in the maintenance of the aquatic ecosystem. Gharials are cold-blooded creatures that emerge from underwater to bask themselves in the sun in order to regulate their body temperature or, nest.⁵ As the mud on their bodies dries, they blend in with the sandbars they bask in and are easy to overlook in their environment.

Ganges river dolphin (Platanista gangetica) and the gharial (Gavialis gangeticus) are both listed in the IUCN’s Red List as Endangered species and Critically Endangered species, respectively. Among the main causes of the Ganges river dolphins' (GRD) population decline in their range are poaching, becoming fishery bycatch, the construction of flood-control infrastructure, embankments, the presence of motorboats, dredging, siltation, progressive habitat degradation by sluice gates, and aquatic pollution.⁶ Adult gharial population nosedived from an estimated 436 adult gharials in 1997 to fewer than 250 mature individuals in 2006.⁷ Reasons for their decline can be cited to the increased use of gill nets for fishing in gharial habitat and the loss of riverine habitat as dams, barrages, irrigation canals and artificial embankments being built. Siltation and sand-mining further change the river courses; land near rivers being used for agriculture and grazing by livestock during the dry-season. Another reason for the decline has been attributed to over-hunting for skins and trophies, egg collection for consumption, killing for indigenous medicine and excessive and irreversible loss of the species habitat.⁸

A gharial (Gavialis gangeticus) basking with open jaws—a sign of relaxation—in the Gandak River.

The Gandak plays host to the second largest population of the critically endangered gharials in the country and is a significant habitat range to the migratory Ganges river dolphins. The riverine habitats of both species are threatened by water flow regulation by dams and barrages in this region. In regulated rivers, water level is determined by human needs- to meet various domestic and industrial demands for water or for flood control and drainage. Though we have relied on simple forms of river regulation to provide water security from early river valley civilizations, river regulation today is an important tool for socioeconomic development. Local controls are now replaced by the coordinated regulation of flows throughout entire river basins and large-scale water transfers from wet to dry regions via sluice gates and barrages. 

Reduced water flow leads to a reduction in foraging grounds and habitat. Dry-season flow regulation leads to sudden changes in depth, water temperatures, and bank erosion. This leaves GRDs at risk of being stranded in shallow river channels. Gharials may face breeding failures with unexpected water release that may wash away eggs. Such serious impacts need to be better understood to be addressed. Changes in dry-season river flow regulation are unpredictable and large-scale, making high-resolution data collection to monitor the species’ habitat in real-time indispensable. Such methods could enable swift communication of risks resulting from dam operations, to concerned water management authorities facilitating quick response to minimise mortality or injury risk to river dolphins or gharials, and eventually help inform ecologically oriented management of rivers. Despite a significant increase in awareness about river conservation, water management paradigms have not been able to address threats to species from dry-season river flow changes.

Spotter in the kayak on the River Gandak as observed from the survey boat.

The project's goal is to better understand these species and their conservation needs by using multiple methods in tandem and hence addressing previous knowledge gaps. It will be essential to continue extrapolating from real-time monitoring for prompt conservation action and efficient management of both human and ecological requirements. 

The first task between the collaborating team members from Wildlife Conservation Trust (WCT) and Technology for Wildlife Foundation (TfW) was to identify an appropriate field-site for study. The field site requirement was an area suitable to conduct study by air, water and land. Proof of abundance was to be obtained in land by visual bank-based surveys and in air by the use of UAVs in the area of interest. Attached to the boat as part of the boat-based methods was the CPOD (Cetacean and Porpoise Detection) device. It was used to collect data on GRDs’ frequencies, sound pressure levels, and general activity in the study area. To narrow down the field of study the team conducted a river survey in a zigzag transect, using a boat and kayak over the area of interest. The kayak was manned by a spotter and a kayaker, while the boat carried the rest of the team, following behind the kayak. 

Once the field of study was determined, the teams split into three. The first team worked on setting up and retrieving information from the CPOD and surveying dolphin presence and activity. The second team worked on tracking gharial abundance in the area of interest and its fringes. The last team ran aerial transects simultaneously over the same area, whilst coordinating over the radio. As such, valuable proof of record was gathered on the focus species over the duration of the field trip. 

References:

1. Ganges River Dolphin | Freshwater Dolphin | Species | WWF

2. Ganges River dolphins strongly alter their acoustic behaviour in response to underwater noise, finds study from India - Dr. Nachiket Kelkar

3. Surfacing and diving behaviour of free-ranging Ganges river dolphin, Platanista gangetica gangetica on JSTOR. (n.d.). www.jstor.org

4. The Gharial: Going Extinct Again1 | IGUANA • VOLUME 14, NUMBER 1 • MARCH 2007

5. Studies on the Indian Gharial | Journal of the Bombay Natural History Society

6. The endangered Ganges river dolphin heads towards local extinction in the Barak river system of Assam, India: A plea for conservation

7. Gharial: Threats | Wikipedia

8. Gharial-Gavialis gangeticus | IUCN Red List

By the river Gandak

In March, 2022 I was thrilled to find out that we were headed for a field trip to Bihar. I was excited for many reasons, including that this was going to be my first field trip with Technology for Wildlife Foundation - the experience of travelling to Bihar, encountering gharials and dolphins, the beauty of the Gandak (tributary of Ganga) and my first drone flight. The trip aimed to study the behaviour of gharials and Ganges river dolphins in the Gandak river during pre-monsoon season when the water levels of the river are shallow.

On the 15th of April, 2022, my colleagues and I left for our field trip to Bihar. We landed in Patna early that day and were later joined by our collaborators from Wildlife Conservation Trust (WCT). Together, we started for Bagaha - our field site, an amazing seven hour drive from Patna. It was the peak of summer and we needed to constantly hydrate ourselves. I was slightly tired of the heat and was trying hard to keep awake. Nevertheless, the Gangetic floodplains kept me in awe for the most part.

The next morning we left to survey the river after having chai and chole puri for breakfast. After setting up the boat with a CPOD (Cetacean and Porpoise Detection) to collect data on dolphin frequencies and other activity in the area, all of us hopped onto the boat to begin our survey. Our objective was to identify a good stretch of the river which could be the field site, a site with a good number of gharial and Gangetic river dolphin sightings. This boat ride was especially beautiful and memorable. We were in the middle of the vast stretches of the Gandak and its floodplains. The quietude of the Gandak was addictive. At one point, there was a large enough sandbar for us to hop-off the boat, where we tried flying a kite as the wind was on our side. The idea was to mount a camera and a GPS device to track the route to record features in such terrains. This was so much fun; we would probably try mounting the camera on our next field trip. The halt lasted for a good half an hour, after which we resumed the survey. By the evening, we were able to finalise the field site. We also spotted many birds, some turtles and gharials (thanks to binoculars), and a few dolphins! The day came to an end with a beautiful sunset by the river Gandak.

Our ride in the river Gandak. Image: Nancy Alice/ TfW.

The following day we arrived at the field site and prepped to fly the drones over gharials basking under the sun. We didn’t mean to disturb them but they were quite sensitive and would promptly glide back into the water when they heard our activities. We worked out how to operate our drones  and observed them happily without creating any disturbance. Drone-flying seems like an elegant art, from setting its orientation, launching it to getting it back to us. After a few flights by colleagues to observe gharials, I was prompted to fly it back home, with a brief primer on the controls. This was my first attempt with the drone and I was still learning how to navigate it. The toughest part though, was not being able to see the screen under such sunny conditions, and to keep a track of the battery. One of my colleagues, Shashank kept referring to video games as the best practice to have a better understanding of drone controls. Hence, video games and drone flying are up next on the bucket list for me. 

Most gharial captures were smooth as they would be basking on the sandbars, so they were clearly visible. The dolphin captures were comparatively more spontaneous and calculated. Among others, we had identified a mother and baby dolphin in our field site. Its sightings would be frequent at certain times during the day. If the weather was not windy at those times, we flew the drones over them to observe and were able to capture them swimming happily. These captures were delightful. It would often start with one of us spotting some frantic splashes in the water followed by a confirmation from the binocular personnel and then the drones launched. Spontaneous and almost ticklish! We analysed the drone videos the following day and worked on making drone transects for better video capture of gharials and dolphins. Over the days that followed, we flew the drones in pre-programmed transects and analysed the imagery for sightings. I remember having a good long conversation with Shashank, where he was explaining the legal rules of drone flying. It cleared a lot of doubts on  safe and sustainable drone flying. 

In conclusion, the field site was beautiful! Oranges, cucumbers and bananas kept us happy amidst the summer days. We would often catch the sunset by the river. Even on the last day at the field site, we sat by the banks and gazed at the beauty of the river. The river was super gracious to let us peep into some of the life it housed and for the unforgettable sunsets.

Sunset at the field site.

The next day we drove to the Valmiki Tiger Reserve at the India-Nepal border. The temperatures dropped slightly enroute to the reserve. After ten days of gazing at floodplains, we were then resting our eyes upon the Shivalik ranges at the horizon. We took a safari at the tiger reserve and it was calming to go around the trees. We spotted a number of avian beauties in the reserve - Emerald doves, Orange-headed thrush and the Paradise Flycatcher. Towards the end of the safari, we experienced mild showers, followed by hail stones. We rushed inside a temple complex to take shelter. Although brief, this little encounter with the temple was memorable. 

Author at the banks of the river Gandak. Nancy Alice/ TfW

The trip was a great learning experience for me and I am grateful for this opportunity. One of the greatest takeaways would be the discussions with my colleagues and collaborators about their journey through conservation and their love for the wild. While I reminisce over the memories of Gandak, I look forward to my next trip and hopefully as a trained drone pilot!