For decades, Israeli conservationists have been wanting to repopulate Israel with Persian fallow deer, a species that was decimated nearly a century ago by spreading settlements and over-hunting. By the mid-1970s, the entire Israeli fallow deer population lived only in captivity and consisted solely of a few males. On the eve of the Ayatollah Khomeini's takeover of Iran, on the very last El Al flight out of that country, four female Persian fallow deer occupied the back few seats. Today, there are approximately 350 Persian fallow deer in Israel, nearly all of them descendants of those few Adams and Eves except for the one male from Germany who has joined and mated with his kinsdeer. Most of them reside in the North, in and around the Hai Bar Reserve on the Carmel Mountain. Realizing that it would be wise to bring the deer to other regions of the country - in a sense distributing the eggs to more than one basket - the Nature Reserve Authority asked the Biblical Zoo in Jerusalem to join them in reintroducing the deer to the Jerusalem Hills. The first reintroduction of Persian fallow deer, which was launched in 1996 up North near Hai Bar, is now considered a fantastic success, with more than 100 deer, including second and third generation, roaming the landscape. But reintroducing the deer into Jerusalem, a project that began in 2003, has been both stymied and endangered by the train line to Tel Aviv, and the results are at this point less certain. In 2003, members of the zoo raised private funds to build an acclimation pen, where the deer could adjust to living in the wild, not far from the place where Nahal Sorek and Nahal Refaim meet, just downriver from the sewage purification plant. Although the water in the area was once dangerously polluted, new methods employed by the plant ensure that the small stream, which provides drinking water to the pen, is clean. For a year and a half, the pen, no more than a stone's throw from the train line, remained empty of deer as construction along the train line proceeded. Then, in 2005, the first group of about half a dozen deer were brought to the acclimation pen. "They are given enough food for a few days and they have access to water," explains Shmulik Yedvab, curator of the Biblical Zoo. "Then they have to learn to graze on the plants in the pen." He explains that the fence around the pen is not so much to keep the animals out of the surrounding hills, as to prevent them from returning to the zoo, which they consider their home. It also keeps away natural predators, such as jackals, while the animals begin adapting to the task of foraging for their own food. When the zoologists feel that the deer have mastered the necessary skills, the animals are tagged and released into the wild, and another batch is brought to the pen. So far, there have been five releases. The deer are not released in the summer, when the weather is too dry and the small pen (14,000 dunams) does not contain enough herbage to sustain the animals. So right now, it is empty. The female deer are tagged with radio collars which have a battery-life of 2-3 years. The males do not get the same collars because their necks double in thickness during breeding season and such collars would choke them. Instead, they are occasionally tagged with rubber collars that are designed to fall off within a few months. Every day, someone from the Nature Reserve Authority or the Biblical Zoo comes to the area to check on the animals. Some days, both organizations send representatives. "We're more than cooperators in this project," says Yedvab, "we're friends." In the sun-warmed morning air of Jerusalem's hills, the landscape marred only by the train tracks cutting across the hills, the Biblical Zoo's curator enjoys an early-morning cup of coffee made by Sharon Tal, from the Nature Reserve Authority, on the back of his pick-up truck. Tal's pick-up truck contains another interesting item - a cardboard box in the front seat houses an injured bird that Tal had found that morning on his kibbutz. Yedvab will bring it back to the zoo to treat it and then Tal will release it. Finishing their coffee, the zoologists retrieve a radio transmitter from a plastic garbage can in the pen and use it to detect the approximate location of the does. By swinging the antenna in an arc and assessing the strength of the signal, the scientist can detect in which direction and at approximately what distance the deer is located and whether or not she has moved in the past several hours. Usually, a deer that has not moved in several hours is dead. Roi Tzidon, a Hebrew University graduate student in zoology, also comes to the area every day to take readings on the location and status of the deer. Tzidon keeps the official records. Although deer are considered an over-populated nuisance in many parts of North America, their reintroduction is expected to have a positive environmental impact in the Jerusalem Hills. By eating the underbrush, the deer clear paths in the forest which help prevent the spread of wildfire. In addition, this space gives other plants, such as the protected ma'arava mishuleshet, an opportunity to grow. Furthermore, seeds digested in the belly of the deer and then excreted tend to grow better and stronger. And finally, the deer are natural prey for certain species which are native to the Jerusalem Hills and so their reintroduction strengthens the entire food chain. Yet there are dangers, too. The deer are unaccustomed to fending for themselves and warding off predators. Yedvab explains that often a doe's first fawn born in the wild does not survive because the mother does not know how to protect him. However, second and third fawns are much more likely to survive as they learn to avoid the likes of jackals and other predators in Jerusalem's hills. But there is a more insidious danger, which has thus far killed about seven of the 25 or so released deer - the train. Nighttime is especially dangerous, as the deer freeze on the train track and stare into the headlights of oncoming trains. A second, potential danger is far less visible and lies in fallow deer's genetic code. Because the entire herd is descended from just a few animals, their genetic makeup is incredibly close. In fact, explains Yedvab, they are genetically closer than siblings. In any genetic pool which is not adequately diverse, there is a high danger of genetic diseases. So far, however, the population appears healthy. Only time will tell if their gene pool is adequately diverse to keep them that way, Yedvab says. And only time will tell if the reintroduction project will succeed. The barriers are formidable. Aside from the dangers in the hills, funding is also always an issue for such projects. The Israeli public, says Yedvab, has only recently become aware of environmental concerns. He cites recent cases in which fish farm and goose liver industries were shut down due to environmental concerns. He exults, "A few years ago, it was not possible to touch agriculture in this country. Now, with a growing awareness of environmental concerns, it is possible. It is a symbol that we are becoming a more normal country." But although the public is more aware, the money is not more available. Currently, the Nature Reserve Authority and Biblical Zoo donate their manpower resources to the project and the Hebrew University pays Tzidon's stipend. Money to build the pen and buy the collars, which cost between $200 and $300 apiece, came from the private donations. And despite the growing environmental consciousness, academic money for zoology research is drying up, diverted to the more lucrative, technological fields. "Back when I was completing a master's degree in zoology," muses Yedvab, "the funds were almost unlimited. I fear that Roi's money will dry up." He swings the radio detector around one more time, locating the last two of the five marked does wandering together in Nahal Refaim. Today, the weather is perfect and all the deer are accounted for. The goal of attaining a population of at least 50 healthy deer in the wild, seems a realistic possibility.