Comparing movement patterns of the Elongated Tortoise Indestudo elongata in El Niño and non – El Niño years.
It has been a long day already and I am tired, grumpy and my eyes and ears are starting to play tricks on me. The sun is just starting to break through the final layers of cloud cover which had previously been offering some respite from the soaring temperatures, and I have just fallen over a hidden menace lurking in the disorientating maze of bamboo grass. As I lie on the ground all intact except for my increasingly damaged pride, I close my eyes, compose myself and remind myself why I am here. This is an opportunity not many people are fortunate enough to have. The reason I find myself sprawled in an undignified tangle, tracking equipment distributed in various random locations around me is I am radio tracking one of Asia’s least understood animals – the Endangered Elongated Tortoise. These charismatic animals are notoriously difficult to locate due to their perfectly adapted camouflage so if I can work out where that quietest of beeps is coming from that would be a good start. This is a quick summary of the feelings I encountered on a basis more often than I would like whilst spending ten weeks at Sakaerat Biosphere Reserve collecting master’s data for my thesis comparing movement patterns of Elongated Tortoises during El Niño and Non-El Niño years. While many argue what the exact definition of an El Niño event is, I feel the description by the National Ocean Service as suitable as any of the numerous answers I have come across, they identify the El Niño event as the warmest phase of the El Niño-Southern Oscillation cycle (ENSO). The consequences of this event include warmer temperatures and increased rainfall. El Niño events have been observed to influence numerous behavioural changes amongst reptile species (1) but not at the time of writing on the Elongated Tortoise. This provided the justification I needed to book my ticket to Bangkok and embark on an unforgettable experience.
When meeting my long-term friend and owner or the Tortoise telemetry project Matt Ward, I must admit I had slightly under estimated the difficulties I was about to face. Having had prior experience of field work in exotic locations I thought I was prepared. I was wrong. Radio telemetry tracking is mentally and physically exhausting – where the Tortoise or indeed any animal goes you go, come what may and be sure that some of the obstacles encountered certainly have an air of you shall not pass about them. On paper, following the loudest beep coming from the antennae of the radio transmitter sounds like a proverbial piece of cake, factor in however weather interference, 360 degree bounce back from omnipresent rocky surfaces and temperamental and unpredictable Tortoise movements and the idyllic on paper scenario on reflection seems a world away.
Situated in north-eastern Thailand, a long running research project has recorded the movement patterns of these animals and has revealed an incredible variety of movement patterns, some barely leaving the same patch of dipterocarp forest while others may cover close to a kilometre over the course of just a few days. The research conducted at Sakaerat has revealed fascinating insights into the behaviour of Elongated Tortoises. For example, the generalist dietary choices of the species have produced startling finds- indeed when a camera trap was positioned around the body of a Burmese python, not one but several individuals of varying ages were captured feeding on the body. Alongside this, perhaps more conventional food items such as fungi and plants make up other parts of the species diet (2).
While little information is available on the reserve with regards to nesting, we do know it occurs, thanks in part to one female for reasons best known to herself, decided a well would be the suitable place to lay her precious clutch – perhaps not a high indictment of their intelligence and this is further supported by another individual that somehow managed to come to its demise by drowning in a very shallow puddle. While they may not be the Einstein’s of the animal kingdom, I would argue passionately you would struggle to find many species more resilient. This is epitomised by a female full of character affectionately known as Mrs Stumps. An obvious peril of carrying your home on your back is your movement and speed is greatly restricted and the chances of being able to outrun events such as fires are highly unlikely. Many animals I saw during my time on the reserve bore the scars of such events however none more so than Mrs Stumps who tragically had lost all her feet to the intense flames. Despite life throwing her such a harsh card, she as I discovered during my research had earned herself quite the reputation for being difficult to track due to the large distances, she was still able to cover, by tortoise standards at least. In fact, such was her tenacity, she had been responsible for more than one researcher to lose their cool over the time she was tracked. Despite her reputation however, she quickly became my favourite of the study animals, her personality indisputable and I take no shame in admitting that while I collected my data around her, I would happily chat asking her how her day was going and telling her I would be out of her way as soon as I can. Of course, I never expected an answer from her, nor did I ever believe she was as fond of my presence as I was of hers, but when you see an animal who metaphorically speaking laughs in the face of such adversity on a daily basis, it is difficult not to feel huge admiration for her. When the day of the last track to find her came I found a sadness hitting me I wasn’t expecting. I like to think she is happily out there now still alive and kicking and with all studies on the species on the reserve currently concluded for now at least, she is transmitter free and almost certainly not missing her highly busy day being interrupted by annoying researchers!
As resilient as these Tortoises are, there is a limit to what even the hardiest animal can contend with especially when people are involved. Serious habitat destruction and poaching for food and the pet trade has strongly contributed to the species Endangered classification on the IUCN Red List (3). With so little being known about the species and what is reported in journal articles is often contradicted by new research, conservationists continue to struggle to implicate the best course of action to aid the species and improve its conservation prospects.
Ultimately no significant differences in movement patterns during El Niño and non- El Niño years were identified during my time on this charismatic species. That doesn’t mean that the implications of climate change won’t impact on the fortunes of Elongated Tortoises. A combination of a limited time sampling period and a small sample size and of course individual personality (and who better to highlight the variability in the species temperament than Mrs Stumps?) are just some of the factors that leave the possibility of an expansion of this research subject open ended. Who knows maybe in the future someone else will have the pleasure of chasing the charming Mrs Stumps and co around the dipterocarp forests of north-eastern Thailand …..
I would like to express my sincere gratitude to Matt Ward and the Sakaerat Tortoise Telemetry project for allowing me this incredible opportunity I now have memories and skills that will last a lifetime. Thank you.
1) Márquez, C., Wiedenfeld, D.A., Naranjo, S. and Llerena, W. (2008) The 1997-1998 El Niño and the Galapagos tortoises Geochelone vandenburghi on alcedo volanco, galapagos. Galapagos Research, 65, 7-10.
2) Ihlow, F., Dawson, E, J., Hartmann, T.& Som, S. (2016) Indotestudo elongata (Blyth 1854) – Elongated Tortoise, Yellow-headed Tortoise, Yellow Tortoise. Conservation Biology of Freshwater Turtles and Tortoise, 5.
3) IUCN (2011) IUCN Red List of Threatened Species 2011. http://www.iucnredlist.org