by¬†Steve Platt (WCS Myanmar)¬†
Kalyar Platt (TSA Myanmar) and I returned to Yangon this week after spending two and a half months undertaking what can only be described as one of the most rewarding experiences of our professional careers ‚Äì the reintroduction of 60 head-started Burmese Roofed Turtles (Batagur trivittata) into two rivers in western Myanmar.
For me, it was especially poignant experience because I had participated in the "rediscovery" of this species, long-feared extinct, as a freshly minted Ph.D. way back in 2001. Found only in Myanmar (formerly known as Burma), Burmese Roofed Turtles were once common in the Ayeyarwady-Chindwin River system, but populations steadily declined in the years following World War II. Although other factors (e.g., incidental take in fisheries gear and destruction of nesting habitat) were no doubt involved, the decline was primarily due to the over-harvesting of eggs by villagers living along the rivers.
Because Myanmar was for the most part closed to the outside world until fairly recently, the inexorable slide of this turtle towards extinction went largely unnoticed by western biologists. It wasn't until the mid-1990s that alarm bells begin to ring in the turtle community and by then it was feared the species had gone extinct. Then, in early 2001 while searching for Burmese Star Tortoises (Geochelone platynota), another imperiled endemic species, my WCS Burmese colleagues and I stumbled upon the shell of a freshly killed Roofed Turtle at a village on the Dokhtawady River near Mandalay. This shell was "proof of life" ‚Äì the tocsin of extinction had not yet sounded for the Burmese Roofed Turtle! Subsequent to our find, Dr. Gerald Kuchling discovered living Roofed Turtles in a Mandalay pagoda pond, which were used to found an assurance colony at the Mandalay Zoo. A few years later Dr. Kuchling and his WCS Burmese associates also identified and began to protect Roofed Turtle nesting sites along a remote stretch of the upper Chindwin River where fewer than ten females continue to cling to survival. These nesting sites have yielded hundreds of eggs since 2007, each of which is carefully incubated at a secure sandbank near Limpha Village; the hatchlings which emerge were headstarted at the Mandalay Zoo until 2010, but have since been reared at our basecamp in Limpha Village.
Rather than simply stockpile these incredibly endangered turtles in captivity, our objective has always been to restore the Burmese Roofed Turtle as a functional members of riverine communities in Myanmar. As a first step towards attaining this goal, in mid-January 160 subadult Roofed Turtles were transferred from the Mandalay Zoo to our Limpha Village basecamp. A perilous five-day journey over some of the worst roads imaginable was required to move the turtles, 60 of which were destined for release while the remaining 100 will serve as founders of a third assurance colony now being established at Htamanthi, a small riverside town hosting the forward headquarters of the sprawling Htamanthi Wildlife Sanctuary. Upon arriving at Limpha, we immediately transferred the turtles to two recently constructed, spacious concrete grow-out ponds where they were kept for several weeks to recover from the arduous journey.
The two sites where we planned to release the turtles had been carefully selected during our previous expeditions to the region. Our primary release site was a placid stretch of the Chindwin River at Limpha Village. The river at Limpha harbors at least two and perhaps three of the remaining wild female Roofed Turtles, contains several deep pools or "aikes" preferred by Roofed Turtles and importantly, because of its proximity to our base of operations, should be easier to protect from the incursions of evil-doers such as electro-fishers and gill netters. The second release site is located far up Nam Thalet Chaung, a tributary of the Chindwin arising in India and flowing through the Naga Hills. The lower reaches of Nam Thalet Chaung once hosted a breeding population of Burmese Roofed Turtles (the upper reaches are swift-flowing and boulder-strewn, unsuitable as Roofed Turtle habitat), and the river remains in a near-pristine state; the water is clear, riparian vegetation is largely intact, and deep aikes filled with abundant aquatic plants (potential turtle food) punctuate its sinuous course.
While the turtles recovered from their journey, Kalyar begin organizing the forthcoming "release ceremony". Nothing of importance happens in Myanmar without a ceremony: the more important an event, the more elaborate the ceremony. Given that we considered the return of the Burmese Roofed Turtles to be a momentous event, a truly memorable event was called for. In fact, two ceremonies were planned, one at Limpha and another on Nam Thalet Chaung. By virtue of its location and our long-term presence in the community, the ceremony at Limpha was by far the most elaborate. Held on 22 February in the local monastery and presided over by Buddhist monks, the ceremony was attended by more than 300 people, including township officials from Khamti (an upriver administrative center), community leaders from villages up and down the Chindwin, government conservation staff from Htamanthi Wildlife Sanctuary, WCS personnel from Yangon, and almost every resident of Limpha, from young toddlers to a wizened crone approaching her centennial birthday. After presentations by TSA/WCS staff, prayers by Buddhist monks, and a sumptuous meal provided by a coterie of village women, the crowd adjourned to a nearby sandbank in the shadow of "Pagoda Island", a rock edifice arising in mid-stream and topped by a small pagoda said to be over 1000 years old. Thirty Roofed Turtles were distributed to the crowd; after being blessed by the ranking monk, 15 of these were released directly into the river while the other 15 were placed in a bamboo pen constructed in the shallows where they resided for about 30 days before being set free.
Less than a week later on 27 February, a second release ceremony was held on Nam Thalet Chaung. Because the release site is far from population centers and accessible only by small boat, this ceremony was by necessity much smaller, but nonetheless well attended; over 150 people mostly from riverside hamlets showed up to participate. Presentations with a strong conservation message were delivered by TSA/WCS Burmese staff explaining our objectives and stressing the cultural and ecological importance of river turtles. Like at Limpha, we distributed turtles to individuals in the crowd who then released them either directly into the river or into a bamboo holding pen near the shore. After the ceremony as the crowd began to disperse, several elderly villagers approached Kalyar and I, thanked us for our efforts, and nostalgically reminisced about past days when nesting Roofed Turtles could be found on every sandbank. If any personal vindication of our work was needed, this was it.
Our plan at Limpha and Nam Thalet Chaung was to formally test two release strategies in order to determine which approach would give us the best chance of success in future reintroductions of Roofed Turtles. In a nutshell, one group of turtles at each site (Limpha and Nam Thalet Chaung) was released directly from the head-starting facility into the river. Known to conservationists as a "hard release", these turtles had no chance to become familiar with their new home before being liberated. A different approach was taken with the second or "soft release" group. These turtles were placed into holding pens constructed in shallow water at the river's edge in hopes that a brief period of confinement would allow them to become acclimated to the site, making them less likely to wander after being released. This is an important consideration (particularly in the Chindwin River) for two reasons. First, better protection can be afforded to the turtles if they remain close to Limpha; our basecamp is nearby and we have leased the fishing rights to this stretch of river making it possible to control activities (e.g., gill netting) that might harm the turtles. Second, should the turtles not remain near the release site, but instead become widely scattered up and down the river, they might not be able to find each other when it comes time to mate. From the standpoint of demographics, a non-reproducing turtle is a "dead" turtle because it makes no contribution to future generations. After 30 days in the bamboo holding pens, sections of the fence were removed and the confined turtles quickly found their way to freedom.
In order to determine what effect confinement had on the post-release movements of our charges, we attached radio transmitters to a subsample in each group (hard and soft release groups at Limpha and Nam Thalet Chaung). We began following the turtles almost immediately after they entered the rivers and will continue to do so as long as the batteries on the transmitters last. Although time consuming and expensive, without a scientifically rigorous monitoring program it is impossible to make informed decisions regarding the success of our efforts and any modifications that might need to be made. Sustained long-term monitoring is perhaps one of the most crucial activities we have yet undertaken.
Our results to date are for the most part encouraging. The turtles we released into the Chindwin River remain within about two river miles of the release site where most have taken up residence in deep channels and aikes. With one exception, all of the turtles have moved upstream from the release site. Unfortunately, one turtle, a subadult male was found floating dead in the river about two weeks after being released. Although the cause of death remains unknown, foul play ‚Äì perhaps electrofishing ‚Äì is suspected. The death of this turtle spurred action by the warden of Htamanthi Wildlife Sanctuary who assigned the Flying Squad, an elite unit tasked with enforcing wildlife laws to begin conducting regular patrols in the Chindwin River near Limpha. The Flying Squad has already removed numerous monofilament gill nets and lines of baited hooks, and are preparing "sting operations" to nab electrofishers. The turtles we released into Nam Thalet Chaung have moved more widely. Several remain in a deep aike immediately adjacent to the holding pen where we regularly see them basking in the mid-afternoon sun. Others have moved downstream, settling in the deep aikes scattered along the river channel. Interestingly, most of these aikes are known to have harbored Roofed Turtles in the not-so-distant distant past so there is obviously something about these habitats the turtles find attractive. One turtle moved as far as the Chindwin River where it was last encountered swimming downstream over 20 km from the release site. Our local TSA/WCS staff continues to monitor the turtles and report back to us every week.
For now it seems the turtles have settled down in their new homes and their whereabouts are known. What happens when floodwaters surge through these rivers in the coming monsoon remains to be seen. Will the turtles be washed downstream and scattered along hundreds of miles of river or will they stay in the release area, grow to maturity, and eventually begin to reproduce? At this point we can only continue our monitoring and wait for the rains to begin in June. Should this initial reintroduction prove a failure, we'll circle the wagons, regroup, analyze what happened, learn from our mistakes, and try again. Like they say at NASA - "Failure is not an option". Ditto for us!
Acknowledgements: Support for the Burmese Roofed Turtle project was generously provided by the Andy Sabin Family Foundation, Walde Research and Environmental Consulting, Edith McBean, Holohil Systems, Ltd., Panaphil Foundation, The Leona M. and Harry B. Helmsley Charitable Trust, Turtle Conservation Fund, USFWS - Critically Endangered Animals Conservation Fund, and Critical Ecosystems Partnership Fund.