by David Makin and Dr. H. Mendelssohn
In 1958, government pest control officers in Israel began fumigating bat roosting caves with Ethylen-Dibromide. Today they are using lindane, 1 a persistent organo-chlorine insecticide whose effects may last for many years. The campaign began when the Egyptian Fruit Bat (Rousettus aegyptiacus) was declared a pest by the Wild Animals Protection Law, the same law that protects Israel's 27 species of insectivorous bats.
Egyptian Fruit Bat populations had increased considerably during the past 50 years, apparently due to the greater availability of food as different varieties of orchard trees and ornamentals became more prevalent. In those days, fruits were often left to ripen on the tree, making them attractive to the bats who sometimes caused damage. The bats had originally relied mostly on two native foods, the fruit of the Sycamore Fig Tree (Ficus sycomorus) in summer, and of the Carob Tree (Ceratonia siliqua) in winter.
The fumigation campaign not only destroyed fruit bats by direct poisoning, but entire cave ecosystems, including highly beneficial and protected insectivorous species. Any cave found with a bat population was indiscriminately fumigated, without regard to what species inhabited it, sometimes even including caves without bats.2 Within 15 years, populations of insectivorous bats decreased by approximately 90%.
Surveys have documented the dramatic effects. For example, the formerly very common Schreiber's Bat (Miniopterus schreibersi), the moderately common Mediterranean (Rhinolophus eurayle) and Mehley's (R. meheyli) Horseshoe Bats' disappeared entirely.4 Other previously abundant species, including Large (Myotis myotis) and Lesser (M. blythii) Mouse-eared Bats and Blasius' Horseshoe Bats (Rhinolophus blasii) were found only as isolated individuals, 4 while the Naked Rumped Tomb Bat (Taphozous nudiventris) has changed from common to rare.
Bats are not even safe in wildlife sanctuaries. In a letter to the editor of Teva Vaaretz (the Society for the Protection of Nature magazine), a pest control officer stated that several instructors for the Society for Protection of Nature, and rangers of the Nature Reserves Authority willingly helped exterminate bats in nature reserves.5 Under the Wild Animals Protection Law, the poisoning of caves containing insectivorous bats was actually illegal anywhere, a law that was the responsibility of the Nature Reserves Authority to enforce.
Long Range Consequences
The ecological consequences of cave poisoning appear to be far reaching. A population explosion of several species of Noctuid moths is now causing major crop damage, requiring extensive chemical control, and resulting in heavy environmental pollution. Noctuid caterpillars originally caused few problems, 6 but they have become major agricultural pests7 as insectivorous bats, the main predators of adult moths, have declined.
The decline of Israel's insectivorous bats is apparently a direct result of cave poisonings, since species that live only in buildings or in places where caves have not been treated remain common. Kuhl's Pipistrelle (Pipistrellus kuhlii) roosts in wooden buildings and is still abundant. Its slight decline is likely due to the fact that fewer wooden buildings are now built. Bodenheimer's Pipistrelle (P. bodenheimer) lives in untreated desert caves around man-made agricultural oases, where it has considerably increased its populations in spite of other hazards.
While the affect of cave fumigation upon insectivorous bats has been profound, Egyptian Fruit Bats, the original target of the program, did not decline for many years, despite the direct poisoning of many thousands. There is evidence that populations even continued to increase. The fact that fruit bats withstood the extermination campaign much better than the insecteating species may be due to their higher reproductive potential, combined with their greater ability to use alternative roosts. Most Egyptian Fruit Bats bear two young annually and can roost in a variety of places, including cellars of new buildings and even underground parking lots, thus escaping the poison. Fruit bats have finally declined, but apparently- due to overpopulation, not to cave fumigations.
Today, most farmers and control officers agree that damage is negligable or non-existent. Nevertheless, many unfortunately believe that this is the result of cave fumigations. In all likelihood, the real reason that orchard owners are experiencing little or no damage is because for many years most commercial fruit in Israel has been picked green, as it is in most parts of the world. Fruit bats actually may help control such orchard pests as the Mediterranean Fruit Fly (Ceratitis capitata) if they are allowed to eat over-ripe fruits that are missed by pickers.
Responsible Action Needed
Use of lindane in Israel is illegal, but it is still sold, and unauthorized people use it freely. Poisoned caves are not posted with warning signs and often are visited by unknowing hikers, who may inhale the dangerous fumes. Empty and even unused containers of lindane are discarded in the caves, contrary to the law which prescribes strict control for the application and storage of pesticides.
Lindane is selected by pest control officials because of its persistence. Even if all cave poisoning were immediately stopped, its effects could last far into the future. No one knows whether many of Israel's once common insectivorous bats can be saved, but they deserve a chance, especially when one considers their value against the environmental damage, the economic waste, and the now well demonstrated futility of current policy.
You Can Help
We request that you write to the Israeli Minister of Agriculture and the Nature Reserves Authority and ask them to do the following: (1) call for an immediate moratorium on fumigations of bat roosting caves; (2) re-evaluate the policy under the Wild Animals Protection Law because of its affect on protected species and the environment; (3) re-evaluate continuing the fumigations in the face of evidence that it is ineffective even in its original purpose; (4) investigate whether or not any control of Egyptian Fruit Bats is warranted; (5) seek the advice of local experts; (6) draft appropriate legislation based on the facts obtained. Send your letters to: Mr. A. Nechamkin, Minister of Agriculture, Nahalal, 10600, Israel; and Mr. Uri Bidach, The Nature Reserves Authority, Jeremiah #78, Jerusalem, 94467, Israel.
David Makin is a doctoral candidate at Tel Aviv University, Israel. His thesis is titled "Ecology and Biodynamics of Rousettus aegyptiacus", and he has studied bats of Israel for more than 10 years, including an in-depth survey of insectivorous bats in Israel.
Professor H. Mendelssohn is one of the founders of Tel Aviv University and of the Israeli Nature Protection Society. He carried out extensive research on the behavior and ecology of birds, mammals and reptiles, and initiated protection and preservation of many endangered species during Israel's first years. He initiated legislation for nature conservation in Israel, and these laws are still in effect. They are the basis for Nature Reserves Authority action in Israel. He currently is the Scientific Director of the Canadian Center for Ecological Zoology at Tel Aviv University where captive breeding centers for endangered species are managed. Professor Mendelssohn's appeals were the first to focus attention on the fact that insectivorous bats were becoming endangered in Israel.
(Editor's Note: Lindane is among the chlorinated-hydrocarbon group of chemicals which includes, among others, DDT, PCB'S, and benzene hexachloride (BHC). In the United States, they have been banned or restricted because of their ability to cause cancer, birth defects, neurological disorders, and severe harm to both wildlife and the environment. There is evidence that lindane bio-accumulates in the central nervous system of humans. It has been found in areas greatly removed from the original application, including in bird, mammal, and fish tissues in both the Arctic and Antarctic. Lindane has come down in rainwater in several countries, and 15 years later as much as 8% of initial applications remained in the soil (America the Poisoned; Lewis Regenstein; Acropolis Books Ltd., 1982).
Failure of this particular campaign against Egyptian Fruit Bats should not be interpreted that, in general, fruit bats are not highly vulnerable to destruction. The affect on the inadvertent victims, insectivorous bats, has clearly been devastating, while the impact on a delicate ecosystem is only now coming to light. The affect on other species, including man, is unknown.)
1. Moran, Sh. and Y. Wolf, 1972. The Fruit Bat (Roussetus aegyptiacus Gray) Research: Intermediate Report for 1970/71-1971/72. Ministry of Agriculture, Plant Protection Dept. (in Hebrew), II pgs.
2. Mendelssohn, H., 1973. On the Extermination of Bats in Israel. Teva Vaaretz 16 (1) 51-53 (in Hebrew).
3. Bodenheimer, F.S., 1958. The present Taxonomic Status of the Terrestrial Mammals of Palestine. Bulletin Research Council of Israel. Zool, 7.B., 165-190.
Dor, M., 1942. Key to the Bats of Israel. Nature Teachers Society, Israel General Labour Federation (in Hebrew), 11 pgs.
Goldblum, N., 1951. Blood Parasites of Bats in Israel. Ph.D. thesis, Hebrew University, Jerusalem (in Hebrew, with English summary), 48 pgs.
Theodor, U. and A. Moscona, 1954. On Bat Parasites in Palestine. Parasitology. 44:157-245.
4. Makin, David, 1977. Survey of the Insectivorous Bats of Israel (intermediate report). Nature Protection in Israel, Report *2, 1. Paz, Nature Reserves Authority. 127-223.
Makin, David, 1977. Biology and Distfibution of Microchiroptera in Israel. M.Sc. Thesis, Hebrew University, Jerusalem (in Hebrew), 102 pgs.
5. Wolf, Y., 1974. On the Extermination of Bats in Israel. Teva Vaaretz. 16 (4) 198 (in Hebrew).
6. Bodenheimer, F.S., 1930. Die Schadlingsfauna Palastinas. Berlin, Paul Parey. 438 pgs.
7. Avidov, S., and 1. Harpaz, 1969. Plant Pests of Israel. Jerusalem, Hebrew University Press. 549 pgs.
A poison canister and some of the uncounted thousands of Geoffrey's Bats (Myotis emarginatus) and Greater Horseshoe Bats (Rhinolophus ferrumequinum) killed in Israel's cave fumigations. Greater Horseshoe Bats already are extinct or endangered throughout much of their range. Photo courtesy Dr. H. Mendelssohn.
The Egyptian Fruit Bat, one of several bat species that pollinates Africa's famous Baobab Tree, is the same bat that Israel declared a pest. Photo courtesy Dr. Merlin Tuttle.