Rewilding programs have become increasingly successful

As apex predators, large carnivores such as lions or wolves play crucial roles in their ecosystems. However, their numbers have significantly declined over the past decades, giving rise to efforts of relocating several species – including reintroduction of species to areas where they had been exterminated or reinforcing an existing population to increase its viability – to support their conservation. To date though, there has been little information about what factors determine whether such rewilding programs are successful or not.

Now, a team of researchers led by the University of Oxford has analyzed data from nearly 300 animal relocations that took place between 2007 and 2021, spanning 22 countries on five continents, and involving 18 different large carnivore species, such as wolves, bears, hyenas, wild dogs, and big cats.

The analysis revealed that two thirds (66 percent) of the relocations were successful and that success rates for large carnivore relocations have increased substantially since 2007. According to the experts, for wild-born carnivores, success rates increased from 53 percent (pre-2007) to 70 percent, and for captive-born animals, success rates doubled from 32 percent to 64 percent. The species with the highest success rates were maned wolves, pumas, and ocelots (100 percent success rate), while those with the lowest success rate (approximately 50 percent) were African lions, cheetahs, brown hyenas, Iberian lynxes, and wolves.

“Soft-release” methods – involving acclimatizing the animals to the new environments before fully releasing them – appeared to me most successful. At the same time, releasing young animals (one or two years of age) also increased success rates, due to their greater behavioral plasticity to adapt to new environments. Compared to animals born in the wild, the success rate of animals released from captivity decreased by 1.5-fold. Unfortunately, just over a third (37 percent) of the relocated animals could find a mate and/or raise a cub in their new habitats.

Although the fact that most relocated animals survived is highly encouraging, their low mating success show the ongoing challenges rewilding efforts face and highlight the importance of protecting already existing habitats.

“In the last 15 years we have become more successful at translocating and reintroducing large carnivores. This allows us to be optimistic for the future of rebuilding damaged ecosystems around the globe, but we must remember that it is always more important to protect large carnivore populations where they are now before we lose them. Even as we have grown to be more successful, 34 percent of individual translocations fail and they cannot be seen as a replacement for immediate conservation action to save these populations,” concluded lead author Seth Thomas, a biologist at Oxford.

The study is published in the journal Biological Conservation.  

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By Andrei Ionescu, Earth.com Staff Writer

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