For tortoise, terrapin and turtle care and conservation
Barbara Livoreil, Centre for Research and Conservation of Chelonians, SOPTOM – Tortoise Village – BP 24 – 83590 Gonfaron, France, blivoreil{at}aol.com
This paper is based on a presentation given to the BCG Symposium at the University of Bristol on 29th March 2003.
Introduction
For several decades human beings have become more concerned about their environment, becoming aware that not only have our demography and activities had detrimental effects on our health and quality of life, but also that they have caused one of the most important declines of species ever observed on this planet. Conservation programmes have been designed and implemented for several decades all around the globe to try to counterbalance this phenomenon. During this period, conservation has evolved over the years as we learnt from experiences and developed new technologies and tools. This paper reports the conservation programme that is currently elaborated and implemented at Soptom (CRCC) for Testudo hermanni hermanni in France, reflecting a simple example of the evolution of thought and practices in the large world of conservation.
The Hermann’s tortoise
The Hermann's tortoise Testudo hermanni is a small black and yellow chelonian (max 18cm long for wild females) with a distribution spread from Spain to the Balkans, including several Mediterranean islands (Cheylan 1981). The western subspecies T. hermanni hermanni is found only in Spain, Italy and France. It differs from the other, eastern, subspecies T. hermanni boettgeri by its smaller size, two clearly defined black longitudinal stripes on the plastron, and generally a ratio smaller than 1 between the pectoral and femoral midline seam on the plastron (Bour 1986). In France T.h.hermanni is nowadays restricted to a very small area, in the department of the Var (French Riviera). The main threats to its survival are:
Conservation strategies for tortoises
As pinpointed by Klemens (2000) "habitat protection is the only viable long term means to ensure the survival of the world's tortoises". He also mentions that zoos and captive breeding programmes have an important role to play in the conservation of tortoises. Captive breeding is compulsory when the number of individuals remaining in the wild is not large enough to ensure the survival of the species by itself. In the past, as captive breeding seemed to be far easier and less costly to implement than the protection of habitats, it has been widely adopted in zoos and centres all over the world for various species. This also gave a renewed status to zoos which were more and more criticised by people defending animal rights (Norton et al. 1995). Many captive breeding programmes were successful (i.e. lots of hatchlings) and led thereafter to many release programmes. At that time most programmes did not have any sound health or genetic check-ups and any post-release survey, for the reason that no one was fully aware of their importance. Some disasters occurred, with animals unable to adapt to the wild or diseases spreading from captive bred animals to wild endangered populations. The few programmes that have been implemented thoroughly have shown that releasing animals back to the wild was far from easy, requiring the animals to be provided with and trained to natural conditions during captivity, and that releases could be detrimental to wild individuals still present in the area.
The success of release programmes has been reviewed among others by Beck et al. (1994). For reptile and amphibian programmes (21% of the whole set of reintroduction programmes reviewed, 23 species involved), only the Galapagos tortoise programme proved to be successful, in the sense that it led to a self sustaining population - the goal of any conservation programme (Beck et al. 1994). A successful release programme is thus difficult to achieve and generally involves many steps: viable and healthy animals, a lot of time, energy, money and care. In contrast to such complexity, protecting habitats, as stated by Klemens, is not that costly and difficult, all the more so since protecting an area is also protecting other species ("biodiversity") instead of just the subject. Guidelines for reintroductions published by the International Union for Conservation of Nature (IUCN) in 1998 stated that captive breeding and releasing act only as a last chance tool, thus suggesting the protection of wild populations in their natural habitat as a priority before any other programme.
Studies on conservation of chelonians have been numerous, especially on marine turtles, and have given us a chance to better understand and design sustainable and efficient conservation programmes for these animals. For many years, for example, it was claimed that protecting eggs and nesting sites was a major priority (and certainly easier to implement than tracking adult turtles in the ocean), until new analysis showed us that, although protecting young animals was obviously important to ensure the renewal of generations, saving adults was the priority (because they are the wild reproductive stock). The rationale behind such a change is as follows: firstly, money, energy and time are limited; we cannot be everywhere and save everything, so we must make choices.
Secondly, the chance of survival of a hatchling is naturally very low, yet many species have survived despite the loss of a high proportion of younger animals. Saving eggs and hatchlings is an efficient strategy only if they are released when the main threats related to their youth are no longer present. To minimise the risks of predation, they should be reared until they have almost reached adulthood. This may be impossible for marine turtles, but for land tortoises, juveniles are usually kept at least 5-7 years in captivity (N.B. no one exactly knows the survival rates at each age in nature, but after several years the shell is hard and thick enough to protect the young tortoise from many predators). During this time, natural selection is minimised, and animals adapt to captivity and are no longer "natural" wild tortoises, as reproducing the natural environment of this species would require enormous investment (space, diet, relationships between animals) and is generally impractical. "Headstarting", the release of captive-bred young animals, is often a good strategy because it mimics what would normally happen in the wild if more female tortoises were laying eggs, and also because natural selection can then sort out and keep only the fittest animals before they start to reproduce. Yet choosing this conservation strategy means that you must release hundreds of juveniles to make sure some of them reach adulthood, and in the meantime adults are still not protected.
Thirdly, an adult in the wild is, as a consequence, a very precious animal. It has managed to survive since its birth, it has developed adapted behaviours according to its environment, and it will normally survive a long time, being able to produce many offspring under natural conditions (choice of nesting sites and conditions, possible choice of mating partners…). Saving any wild adult tortoise and making sure it can live in a habitat allowing for reproduction is thus contributing to the protection of the real identity of the species and the potential to produce many wild offspring.
Conservation at Soptom
At Soptom (Station for the Observation and Protection of Tortoises and their habitats), priority has always been given to wild animals. The rationale of this centre, when created in 1986, was to rehabilitate wild-born tortoises kept as pets by private owners. Gathering tortoises in the wild to keep them in private gardens was at that time a major threat to wild populations. Such collection still goes on nowadays and is very difficult to assess and stop, but many people now have pet tortoises provided by private captive breeders (most of them are people who obtain reproduction in their garden). These animals are no longer good candidates for rehabilitation programmes because no sound genetic, health or behavioural survey has been implemented since they were born, and most of them have been shaped by captivity conditions over generations. Many captive tortoises are inbred or hybridised, they have a different sensitivity to diseases and often present a different spectrum of diseases and parasites compared with wild animals, and do not display all the behaviours of their wild congeners (Livoreil and Picard 2002).
Creating the first Tortoise Village in Gonfaron (Var, France) in 1988, Soptom started to gather funds for conservation programmes while educating visitors and tourists to try to stop gathering of animals in the wild. Collecting wild tortoises back from private owners, numerous releases were organised between 1988 and 1998. Unfortunately, no sound survey of these released animals could be organised at that time, which does not allow us to draw conclusions about the possible success of such a strategy, nor did it allow us to learn from such experiences to improve our protocols and knowledge of the situation. In order to develop better conservation strategies based on scientific knowledge and analysis, Soptom created a scientific committee in 1995 and the Centre for Research and Conservation of Chelonians in 2001. At CRCC, several programmes are currently designed and implemented, focussing on the conservation of Hermann's tortoises in mainland France. We also rescue wild tortoises injured by dogs, cars or various machines, using these animals for release programmes when needed (Gagno, pers. comm.).
Designing and implementing a scientific conservation programme for a given species is like preparing a good meal. You know you must prepare some appetisers and starters, then one or several main courses, as well as cheese and desserts. You can cook the dessert first or prepare several dishes together, but, at the end, you will have to serve them in a given order. The three main programmes currently developed on wild Hermann's tortoises concern respectively:
These three programmes, together with other minor studies, constitute the "conservation meal" that is mentioned above, and are implemented together in parallel. The rationale behind these programmes is now explained, following the "expected" course of the meal that we hope to obtain in a few years.
Firstly, the population survey helps us to establish a precise map of the area of distribution of T.hermanni in Var, as well as the location of each population. To this map can be added various data such as vegetation, soil, climate, presence of water and degree of urbanisation. The survey also provides us with estimates of "observation rates" (number of tortoises seen per hour). As each observer looks for tortoises according to a standardised protocol, this rate can be compared between sites or, for a given site, over several visits (within a season or between years). Although they cannot precisely reflect the number or density of animals on each site (see for instance Guyot 1996), these rates indicate which population may probably be more important to preserve in the short term. Indeed a large population is less susceptible to environmental changes, diseases or genetic defects and probably more self sustainable than a small one, thus it should be given priority over others. Smaller populations must not be neglected, though, as they may be very "dynamic" (producing numerous young, see below) but it requires a bit more work to know whether they are really sustainable or whether to support them.
Secondly, a programme about the taxonomy and hybridisation of T. hermanni is run in collaboration with the University of Ferrara (Italy) together with many participants all over Europe, who each send samples from their respective countries (Spain, Greece, Croatia, Balearic and other Mediterranean islands). Its goal is to find genetic tools allowing us to clearly identify both T. h. hermanni and T. h. boettgeri as well as their hybrids, and to assess the level of hybridisation within various populations in Europe (including those of France), as the presence of T. h. boettgeri has already been reported in France (Guyot and Pritchard 1999). We also run a comparative study on the morphological characteristics of the animals for which genetic samples are available, in order to detect possible differences in morphology correlated to differences in genetic background. This would help to identify hybrids when seen in the field without having to take blood samples and wait until the analysis is conducted.
Finally, monitoring aims at establishing the status of each population, i.e. whether it is increasing or decreasing, at what rate, and how (because of births and deaths and/or by means of immigration and emigration, including artificial ones such as gathering). This is a very important parameter for conservation, as it will have a great impact on management decisions. It is important to remember that a large population may be threatened if its reproduction is not efficient enough (number and survival of eggs and hatchlings), or if many animals leave the area. With tortoises, it may take quite a long time to realise that a decline is happening, because adults have a long lifespan, thus a lot of them can be observed in the wild over many years, letting us assume that the population is healthy. On the other hand, a small population may be very productive and self sustained, which is valuable for conservation, but the loss of habitat may limit its size. The methods used for monitoring are nowadays based on the rate of re-observation of marked versus unmarked animals, then various mathematical models are used to estimate the actual size of the population and whether it increases or declines (and at what rate). It has been demonstrated that it is not valid to assess the size of a population simply on the basis of observation rates because these rates can be strongly biased by factors such as the climate, the size of the animals and their activity.
We have started to monitor several populations, using the same protocol as for thepopulation survey. Two populations are mostly composed of released animals (Flassans and Ile du Levant) and several others are populations with high observation rates that we discovered during the survey. For the two released populations, the rate of re-observation of released animals is less than 30%. It is encouraging that some animals managed to settle down on the release site, yet the rate of loss is quite worrying. Moreover, if some released tortoises are still there, it does not mean that a new population has been created, until we can prove that reproduction occurs and renewal of generations is ensured. On the Levant Island, this does not seem to be the case, as no sub-adult has been observed while there should be plenty of them ten years after the first release. We are currently working on the hypothesis that the level of predation is quite high on juveniles and would mainly be due to rats (Culorier & Livoreil, unpub.). We will know that our release programmes are truly successful when we prove that these released populations are self sustainable, which requires much more monitoring and efforts.
Indeed, it will take several years before we get sound results about the status of each population, but it does not prevent us from acting in the meantime to ensure their protection. Studies have been implemented on the status of the land for each of these populations, as well as education programmes and guidelines for local residents (including the owners of these lands). Identification of nesting sites is also of paramount importance, firstly to better understand their characteristics and create new sites, and secondly to protect them and eventually protect juveniles. We also intervene on these "rich" sites each time the owners want to work with big clearing machines to try to prevent the killing of animals. We also provide guidelines for the sensitive management of land harbouring tortoises, trying to preserve the habitats and prevent the killing and gathering of adults, and the release of dangerous animals or exotic tortoise species. Because, being a small association, we cannot easily afford to buy land to protect wild populations of tortoises on a long-term basis (which is done by other organisations such as CEEP¹ ), we have chosen to work directly in partnership with local residents and owners. This requires a lot of time, availability and understanding, but we do have this special opportunity to try to protect a species which is largely appreciated by people and is not detrimental to any agricultural practice. We have been much welcomed by many people, yet it is still a challenge to try to change attitudes, behaviours and practices. Education has a key role in that respect and should be much encouraged.
Acknowledgements
We would like to acknowledge the British Chelonia Group for having given us the opportunity to present our projects and their goals. It is always a very good exercise to gather all our projects and ideas together and try to make them relevant and attractive. You gave us the opportunity to assess our activities and to get very interesting feedback, and we hope this also contributed to a better knowledge of conservation. We are also very grateful to the anonymous referee for helpful comments and revision of the manuscript.
The more time and energy you invest in any project, the better your project will be, and this will result in a more efficient and sustainable level of conservation. Our activities and scientific studies depend on the enthusiasm and very important contribution of our many volunteers each year. Many thanks to them all.
Finally, many thanks to the several landowners whose great welcome and support help us believe that, combiningjoining our efforts, we can protect our environment together.
Bibliography
Bour, R. (1986). L'identité des tortues terrestres européennes: spécimens-types et localités-types. Revue Française d'Aquariologie 13, 111-122.
Cheylan, M. (1981). Biologie et écologie de la Tortue d'Hermann Testudo hermanni GMELIN, 1789. Contribution de l’espèce à la connaissance des climats quaternaires de la France. Mémoire Ecole Pratique des Hautes Etudes, Montpellier, France.
Guyot, G. (1996). Biologie de la conservation chez la Tortue d'Hermann française. Thèse de doctorat, Université Pierre et Marie Curie, Paris, France.
Guyot, G. & Pritchard, P.C.H. (1999). First record of introduced eastern Mediterranean tortoises, Testudo hermanni boettgeri, in southern France. Chelonian Conservation and Biology 3, 518-520.
IUCN. (1998). Guidelines for Re-introductions. IUCN SSC Re-introduction Specialist Group. IUCN Gland, Switzerland & Cambridge, UK.
Klemens, M.W. (2000). Turtle Conservation. Smithsonian Institution Press, Washington & London.
Livoreil, B. & Picard, S. (2002). Effect of domestication on withdrawal behaviour of Hermann’s tortoises (Testudo hermanni hermanni). Proceedings of the International Congress on the genus Testudo, March 2001, Hyères, France. Chelonii, 3, 337-341.
Norton, B.G., Hutchins, M., Stevens, E.F. and Maple,T.L. (1995). Ethics on the Ark : Zoos, animal welfare, and wildlife conservation. Smithsonian Institution Press, Washington & London.
¹Conservatoire Etude Ecosystèmes de Provence - Aix en Provence, France.
Testudo Volume Five Number Five 2003