The most recent release of Persian fallow deer took place in May 2026, continuing a long series of reintroductions into the wild in Israel that began in the mid-nineties. Initially, these projects focused on the north of the country, in the Nahal Keziv area of the Galilee. Over time, additional release sites were added in the Upper Galilee, the Carmel, and the Jerusalem Hills in the Nahal Sorek basin, where there is an ongoing effort to bolster the local population. In this year's release from the zoo, nine Persian fallow deer—seven males and two females—were released in Nahal HaMeara, part of the Nahal Sorek basin where releases have been conducted in recent years.
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Behind every such release lies a long, complex, and sometimes slightly chaotic day. The day begins early in the morning at the zoo. Each deer is sedated in a controlled manner, and a series of tests and measurements are performed: weight, blood tests, fur samples, and various body measurements. One of the most important steps is fitting a collar with a GPS transmitter. This is the primary tool we use to track the deer after their release—where they move, which areas they utilize, and how they establish their home range. After the examinations, each deer is carefully placed into a dedicated transport crate. It receives an injection of a reversal agent, which causes it to wake up slowly inside the crate itself. Although it sounds stressful, the darkness and quiet inside the crate actually allow it to recover relatively calmly. From there, they are loaded onto a truck and driven to the release point.
In the field, the crates are lined up so that upon opening, the deer immediately see their new natural environment. The observers and staff remain behind and to the sides so as not to interfere. When the crates are opened, each deer emerges into the wild at its own pace—a moving moment, but also the start of a challenging new beginning. The first days and weeks after release are a particularly critical period. This is a phase of adaptation and learning, where the deer must understand the new world they have entered: where the sources of food, water, and shelter are, and what threats exist in their new habitat—such as predators and vehicles. They learn to recognize the other deer in the area (as well as other animals) and the social dynamics between them. We call this period the "exploration phase," during which the deer is primarily gathering information about the area. It usually lasts for one to two months. Afterward, we begin to see a gradual transition to the "exploitation phase"—a stage where the deer are already more familiar with the area and are utilizing the information they have gathered.
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During the exploration phase itself, behavior can appear erratic. Some individuals wander very far from the release point and develop exceptionally large home ranges, while others remain relatively close to the release point and limit their movement. Over time, usually within a month or two, we see a convergence: the differences diminish, the home ranges become more similar, and movement in the area stabilizes. It is important to understand that this is a continuous and dynamic process. The transition from exploration to exploitation is not abrupt, but a gradual shift in which the deer continues to learn from the terrain and adjusts its behavior based on the new information it collects. This period is also the most critical, and therefore the most sensitive. Most mortality cases in releases occur in the first month or two, while the deer are still learning the new environment. At the same time, this is a natural part of any reintroduction project worldwide. Despite the challenges, the fallow deer project is considered very successful: most individuals survive, establish themselves in the area, and even manage to reproduce and build a stable population.
Now, a few months after the latest release, we are exactly at the end of this year's adaptation period. We witnessed the confusing start—individuals behaving very differently from one another—and now we are beginning to see a clear stabilization in behavioral patterns. We continue to monitor the behavior of the released deer with the goal of learning more about their process of learning and establishing themselves in the field.
Photography: Yeshayahu Goldreich
