Eighteen European bison departed Berlin Zoo and the Rothaar Mountains bison reserve in January 2026, headed for the Caucasus. It was the sixth transport since the project began. Today, ninety bison live in Shahdagh National Park in northern Azerbaijan, including nine calves born in 2025. What started in 2019 with twelve zoo animals represents the first bison reintroduction program in the entire Caucasus region in nearly one hundred years and one of the most ambitious wildlife restoration projects in the post-Soviet space.
A Species That Survived Only in Captivity
The European bison is the continent's largest land mammal. By the late nineteenth century, it had been hunted to extinction across much of Europe, decimated by hunting, habitat loss, and the chaos of two world wars. In the Caucasus, the last wild bison was shot in 1927. Just six years earlier, the final free-ranging animal in Poland's Białowieża Primeval Forest had been killed by poachers. What survived were a handful of individuals in zoos. The species existed on paper only.
The IUCN downgraded the European bison from "endangered" to "vulnerable" in 2020, a single category improvement. As of December 31, 2024, 12,209 bison existed worldwide, with 9,762 living in the wild. This comeback carries a fundamental biological problem: every living bison worldwide descends from only twelve founder animals that survived World War I in zoos. This genetic bottleneck remains unresolved today. It can only be managed.
Six Transports, Ninety Animals, Twenty-Five Wild-Born Calves
In 2017, Berlin Zoo, WWF, and Azerbaijan's environment ministry began building a reintroduction center in Shahdagh National Park, a 130,000-hectare protected area in the foothills of the Greater Caucasus. The first twelve bison arrived from European member zoos of the European Association of Zoos and Aquaria (EAZA) in 2019. Five additional transports have followed since.
Berlin Zoo organized the largest single transport to date in January 2026: eighteen animals arrived in Azerbaijan, twelve from Berlin and six from the Rothaar Mountains reserve in North Rhine-Westphalia. Berlin Zoo coordinates the European Endangered Species Programme (EEP) for bison and determines which animals breed together in which zoos to minimize inbreeding in the globally scarce population. Genetic selection is not theory here but daily operational necessity.
After six total transports, roughly ninety bison live in the national park. Nine calves were born in 2025, ten in 2023. Since the project's start, more than twenty-five calves have been born in the wild, according to project data from July 2026. This is the decisive proof: the animals breed, give birth, and survive in habitat their species had abandoned nearly one hundred years ago. By 2028, the target is at least one hundred wild adult bison in the park, with another sixty animals planned.
In Comparison: What Ninety Animals Represent
The world's largest bison population lives in Poland's Białowieża Primeval Forest. As of December 31, 2024, 1,176 individuals were counted there, part of Poland's total wild population of 2,855 bison. The Białowieża population began in 1952 with a handful of zoo animals. Seven decades later, it is Earth's largest contiguous wild bison population. Germany today maintains 643 animals, including a herd in the Rothaar Mountains that simultaneously serves as the source population for Azerbaijan transports.
Rewilding Europe partnered with WWF to launch a reintroduction program in Romania's Southern Carpathians in 2014. More than eighty animals were relocated there; today over two hundred bison inhabit three areas. In June 2024, fourteen more arrived from Germany and Sweden. The difference from Shahdagh is geographic context: the Carpathians lie within the bison's historical range. The Caucasus does not. Whether the herd there builds a self-sustaining, genetically stable population without regular supplemental transports remains the project's central open question.
What Threatens the Herd
The project operates under international scientific oversight from the IUCN, EAZA, WWF, and Rewilding Europe. Three concrete risks remain.
First is genetic. The bottleneck of twelve founder animals can be slowed through breeding programs but not eliminated. Bison are susceptible to eye infections transmitted by insects from domestic cattle. In Shahdagh, where rangeland cattle husbandry occurs in buffer zones, this is a real risk. Berlin Zoo monitors the herd through GPS collars and adjusts protective measures continuously.
Second is ecological. Zoo-raised animals have no experience with wolves. Wolves are present in the Caucasus. This is not insurmountable but requires active monitoring in reintroduction's early years.
Third is political. Azerbaijan's partner organization IDEA is led by Leyla Aliyeva, the president's daughter. The Heinrich Böll Foundation called IDEA "the country's largest environmental GONGO" in November 2024, a state-controlled organization advancing government interests rather than constraining them. Chatham House and Radio Free Europe noted in the same year that Azerbaijan employs nature and climate projects primarily for international image rehabilitation while oil and gas dominate the economy. Experts consider the bison program itself scientifically sound. But a herd sustained by politically dependent structures can shift if political calculations change. This is the structural limit of all species-protection work in authoritarian states.