Last update - 00:00 05/11/2007
Let sleeping bats lie
As of last Wednesday evening, visitors are no longer welcome at bat hibernation sites. Anyone interested in seeing where bats sleep now must wait until April. The Israel Nature and National Parks Protection Authority issued this announcement on behalf of Israel's bat population, as it does every year as winter approaches.
The Twins Cave, near Beit Shemesh, is the largest bat hibernation site in Israel. It is now closed for the winter. This unique cave, in the heart of the Nahal Dolev Nature Reserve, is closed to hikers from November 1 to March 31. During the winter, the cave is home to tens of thousands of bats, mostly insect-eating bats and fruit bats.
Other caves that have been closed off are the Alma Cave in the upper Galilee, the Sharah and Namer Caves in the western Galilee, the Barniki Cave at the entrance to Tiberias, the cave in the Mt. Meron nature reserve and the Oranit Cave in the Carmel Mountains.
"During hibernation," says Yariv Malihi, the INNPPA ecologist for the central district, "the bats' pulse rate decrease from 1,200 beats per minute during flight and 400 beats per minute during rest, to just 10 beats per minute."
Bats store up energy before going to sleep for the winter, and this energy is supposed to sustain them during their months of hibernation. However, when bats hibernate they are not actually in a deep sleep, and the slightest disruption - a sound, brush, or the light of a flashlight - will awaken them completely.
"If visitors enter the caves, they could wake up the bats," says Malihi, "and this would make them need to eat, since they must immediately raise their body temperature, which means they burn more energy. If a bat wakes up during its hibernation period, it will go out in search of food, which is not always available, and will use energy it had not budgeted. If we do not give the bats this time [to hibernate], they simply will not survive.
"Thirty-three varieties of bats account for 30 percent of all the mammals in Israel," explains Malihi, "and they are very important to the ecological system. Only one variety of Israeli bat eats fruit, while the other 32 eat insects. Since there are fewer insects in the winter, most of the bats hibernate."
Sources at the Israel Mammal Center, run by the Society for the Protection of Nature in Israel, note that in the past, Israel bat population suffered serious harm when it was thought that the bats damaged fruit crops, and the caves were fumigated with Lindane, an extremely toxic pesticide. This caused the extermination of all life in the caves, including the insectivorous bats.
"Insect-eating bats are actually very good for agriculture," continue the sources. "They eat insects, including those that are the most harmful to agriculture. The increased use of insecticides, the fumigation of the caves and hikers entering the caves in the winter all have drastically reduced the insectivorous bat population throughout the Middle Eastern basin. A few kinds have become extinct, and others are on the brink of extinction."