Turtles: Slow but Sure -- or Not So Sure?
This week we're going to get to meet an animal that we're all familiar with. This is the creature known as the native dryland turtle (Testudo graeca terrestris), but often thought of as a tank on legs, an animal whose house is its fortress, that carries its house around with it wherever it goes. Though just about everyone's come across a turtle -- on a jaunt in nature, in a petting zoo, or even in our own garden -- we know surprisingly little about these animals and even less about their life style.
There are two kinds of dryland turtles in Israel, our native turtle and the desert one. We also have turtles that live in water: Caspian turtles (Mauremys caspica), African softshell (Trionyx triunguis), Green sea turtles (Chelonia mydas), Loggerhead sea turtles (Caretta caretta),and the Leatherback sea turtle (Dermochelys coriacea). Members of the reptile family, the turtles are herbivorous and long-lived, with a life span that can reach 60 years. They rank among the most primitive reptiles still roaming the globe: Their earliest ancestors appeared approximately 250 million years ago, even before the dinosaurs. While physical and climatological changes over the millenia brought about the extinction of many other species of flora and fauna, the turtles managed to adapt and survive.
Nevertheless, changing environmental conditions nowadays threaten even the venerable, adaptable turtle in many places in the world, including Israel. Like many other animals and plants, the turtle is impacted by the reduction and destruction of habitats, by overuse of ground and water resources, and by illegal hunting. Turtles get run over by cars on the roads and by field vehicles in open spaces.
The dryland turtle, in particular, is sensitive to climate changes and to the warming trends that we see continuing in many places. Why? Like many reptiles, the turtle's reproductive cycle is affected by the temperature of the soil. The warmth of the soil around its nest during the incubation period has a decisive influence on the sex of the turtles that hatch from its eggs. If the balance between the number of males and females is disturbed, the existence of future generations is endangered.
How do you tell the difference between a male and female turtle? The male is usually smaller, with a longer tail and an indentation in its underbelly, which makes it easier for the male to connect physically with the female. They mate twice a year -- in the autumn and spring -- and the female lays 3-5 eggs. In many cases the eggs are eaten, mostly by jackals and foxes, while the young turtles that do hatch are devoured by birds of prey. This is a natural part of the ecosystem, meant to limit the numbers of various animals in any given area. The turtle population becomes threatened, however, when the non-natural threats mentioned above are added to those that nature imposes.
A new study being conducted at Ramat Hanadiv is seeking ways to ensure the future existence of our native turtle. As we already noted, it turns out that we know very little about the dryland turtle, and we must therefore ask a number of basic research questions. Our staff is examining different habitats -- areas characterized by different flora and soil -- and checking which of them are preferred by turtles. Among the open spaces being examined are some with planted forests and others with dense shrubbery or very sparse vegetation. The turtles' modus operandi is studied throughout the day, in every season. Information about where they lay their eggs is particularly significant: it helps the managers of open spaces to plan an area and create or preserve the conditions needed for the turtles to lay their eggs. The assumption is that, once we're more familiar with where and when the turtles function, we will be better able to manage open spaces and nature reserves for their benefit. For research purposes, the turtles found in the areas under study are examined, and micro-chips (which don't affect their behaviour) are attached to their shells. The chips make it possible to track their movement and, using a GPS system, to know their location at all times.
Many people collect turtles and raise them in their back yard or in cardboard cartons indoors. Important: If you see a turtle, please leave it in its natural environment! When you find one that is not in its natural environment, let it go -- in an open area as far away as possible from roads. We hope that turtles will have a long life in this land of ours, and that we will be able to come back and tell you a lot more about them when Ramat Hanadiv's researchers bring us their findings.