DECREASING BIODIVERSITY IN ISRAELRECENT EXTINCTIONS
By Heinrich Mendelssohn
Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel
Editor’s Note: Prof. Heinrich Mendelssohn, one of Israel’s foremost zoologists, has written extensively on the effects of human activities on wildlife in Israel. For further information, readers are referred to: "Changes in the distribution and abundance of vertebrates in Israel during the 20th century" by Y. Yom-Tov and H. Mendelssohn, published in The Zoogeography of Israel by Dr. W. Junk Publishers, Netherlands, 1988.
Because of its zoogeographic situation, biodiversity in Israel is well-developed. Human activity, however, was responsible for negatively influencing biodiversity in prehistoric times. Stone-age hunters primarily hunted the larger herbivores, because the effort invested in hunting a larger animal was no different than that invested in hunting a smaller one. Thus, the larger antelope, red deer and wild cattle were eliminated thousands of years ago. Wild cattle were also domesticated and Bos primigenius-like types were found in herds of local cattle until the 1950s. The Mesopotamian fallow deer, the Arabian oryx, and the local subspecies of the onager survived until the end of the last century. The smallest of the herbivores, the ibex, and the two species of gazelle, were the only survivors until recent times. They were also, however, in severe danger of extinction because of overhunting during the thirties and forties of the present century. Of all the herbivores, only the adaptable wild boar, with its high reproductive potential, was never endangered, protected by the attitude of a mainly Islamic population. The larger carnivores, traditionally considered by people as pests, fared no better. The lion became extinct in medieval times; the last cheetah was seen in 1958; the last Anatolian leopards were killed in the Galilee in the 1960s, whilst hyenas, wolves and Arabian leopards still survive today, but are highly endangered.
In Israel, most wild animals and birds are legally protected by the "Wild Animals Protection Law", enacted in 1954, but this legal protection does not protect them from the dangers in a modern state: environmental pollution, careless application of biocides and destruction of habitats by badly-devised development. The situation is aggravated by the fact that almost all decision-makers have no interest or knowledge whatsoever of nature conservation and environmental protection.
The group most intensely affected, as also in other countries, was the raptors. They were not, however, affected by the slow-working chlorinated hydrocarbons, but by secondary poisoning with rodenticides. In 1950, some damage was caused in grain fields during a cyclic mass increase of voles. As a result, a campaign by the newly-established Plant Protection Department, was organized to eradicate pest rodents by massive application of the rodenticide thallium sulfate, a very effective poison, odorless and tasteless, causing no poison-shyness. It does not disintegrate and is very persistent, thereby causing secondary poisoning. It causes paralysis in the poisoned rodents that move slowly and are therefore taken in preference to non-poisoned, fast-moving ones. The influence on predators, particularly on the raptor fauna, was most dramatic. Many species became locally extinct while others were reduced in numbers.
The biological control system of field rodents-raptors, that had worked for long periods, was thus disrupted. The application of thallium sulfate continued for more than 20 years, notwithstanding that, in the interim, an efficient means of field rodent control had been establishedmodern deep ploughingthat destroys rodent burrows and exposes them to predation. The poison procedure, however, was continued in order to justify the salaries of the pest control officers!
Twenty-five years later, another case of mass poisoning of raptors occurred. In the drained Hula valley, few crops succeed on the peat soil. One of them is alfalfa, a preferred food of voles that breed undisturbed in alfalfa fields, which undergo deep plouging only every three years. Voles build up large populations and caused extensive damage to the alfalfa crop. The farmers sprayed the fields with Azodrin (Monocrotophos, an organophosphorous pesticide), that is recommended in Israel only for cotton and orchards. The instructions on the original label of the Shell company emphasize that Azodrin is dangerous to wildlife and should not be used on fodder crops or near water, as it is very persistent. These warnings did not appear in the Hebrew translation. The application of Azodrin somewhat alleviated the damage caused by the voles but it killed about two-thirds of the many hundreds of raptors and storks that had been attracted to the area by the numerous voles.
Another factor affecting biodiversity is environmental pollution, mainly sewage. In Israel, due to constant immigration, new settlements are continually being built. All matters are well taken care of apart from onesewage treatment. The raw sewage streams through pipes a certain distance from the houses and then into the fields. It mainly affects the breeding places of amphibians. As Israel is an arid country, it has only 6 amphibian species (a seventh, newly described, became extinct by habitat destruction soon after it had been found), most of which were reasonably well established and widely distributed. Five species bred mainly in winter rain pools, created by rainwater, that dammed up in depressions in the ground. Following gravitation, sewage flows into these depressions and so pollutes the breeding places of amphibians. Because of their thin, permeable skin, these species are good indicators of a clean environment and in advanced countries are recognized as such. In Israel, a conspicuous example of the low priority given to amphibians is the sewage of western Jerusalem, which flowed, and still flows (until completion of the construction of a treatment plant), untreated through Nahal Sorek, polluting a beautiful landscape, and continuing to the coastal plain. There it exterminated the most southerly population of the banded newt
Many reptiles have a restricted distribution in certain habitats. If they are "developed", these species face extinction. The lizard, Acanthodactylus schreiberi, lives in the coastal plain on sand-loam soils which are developed for agriculture and settlements. Since no nature reserves exist to preserve this habitat, this lizard faces extinction. A similar case concerns a related species, Acanthodactylus pardalis, in the Negev, that lives on loess soils that are now grain fields. This formerly common lizard now survives on small, uncultivated pockets where its continued existence is uncertain. Another lizard, Ophisops elegans, formerly one of the most common, lived in grain fields all over the country. It could live in this habitat as the traditional shallow ploughing did not harm its eggs that are deposited in the soil. The modern deep ploughing destroys the clutches and this lizard has now become quite rare.
Another adverse factor affecting biodiversity is predation by feral cats. Wild cats have existed for long periods in many habitats in Israel. They are territorial and active only at night. Feral cats are very common, not territorial, have a higher reproductive potential, and a disastrous influence on small mammals, ground-nesting and low-nesting birds, and reptiles. Feral cats exterminated the original wild cat by way of competition, hybridization and infection with feline distemper. They exterminated the green lizard in many areas. This lizard lives in the same habitat as the wild cat, but was protected from predation by it because of different activity timesthe wild cat hunts only at night and the lizard is active only during the day. Feral cats also hunt in the daytime and so could exterminate the green lizard.
There are two organizations in Israel concerned with nature conservation: The Nature Reserves Authority (NRA), which is responsible to the Ministry of the Environment, and the non-governmental Society for the Protection of Nature in Israel (SPNI). The NRA protects wildlife and established and manages nature reserves that are, unfortunately, quite small, because of Israel’s small size. Only the Negev boasts larger reserves. Rangers of the NRA shoot feral dogs on sight. Thus, Israel does not have the problem of other Mediterranean countries that are plagued by large numbers of feral dogs. Unfortunately, it is not possible to limit the number of feral cats by this method.
The SPNI stands guard against ill-devised and superfluous development projects. It succeeded in preventing the erection of a large broadcasting station (Voice of America) in the Arava Valley, that would have served vested interests, but would have been a death trap to millions of migrant birds. Unfortunately, the SPNI has not succeeded in preventing the construction of an unnecessary, large, trans-Israel highway that will destroy many of the few remaining open landscapes, but serves vested interests.
Today, the SPNI is busy with another fight. At the beginning of the fifties, the large and ecologically important Hula swamp in northern Israel was drained. In those days, this draining was considered to be an enterprise of national importance, but due to pressure by the then young SPNI, 10% of the area was left in its original state to serve as Israel’s first nature reserve. It soon became apparent, however, that the draining, that was carried out against the advice of some foreign consultants who had suggested leaving the swamp as a freshwater reservoir for the entire country, did not produce the expected large areas of good, arable soil. Few crops succeed on the peat soil, and when drying, the peat soil contracted and sank and the "upswelling" groundwater flooded large areas, creating a large, shallow lake that attracted considerable numbers of wildfowl and other swamp birds. Thousands of cranes that feed on the Golan during the day arrive in the evening to roost in the shallow lake, a most impressive sight that attracts many visitors. The SPNI plans to develop eco- and ornithotourism in the area. On the other side, vested interests plan to build large hotels on the shores of the lake and to organize boat activities on the lake. The SPNI is trying hard to prevent these plans that threaten to destroy every possibility of developing eco- and ornithotourism. Hopefully, it will succeed.