New study identifies key success factors for large carnivore rewilding efforts

New study identifies key success factors for large carnivore rewilding efforts - University of Oxford

New research led by the University of Oxford has identified the top factors that determine whether efforts to relocate large carnivores to different areas are successful or not. The findings, published today in Biology Conservation, could support global rewilding efforts, from lynx reintroductions in the UK to efforts to restore logged tropical forests.

As apex predators, large carnivores play crucial roles in ecosystems, however their numbers have plummeted over recent decades. Relocating large carnivores can support their conservation, for instance to reintroduce a species to an area where it has been exterminated, or to reinforce an existing population to increase its viability. But to date, there has been little information about what factors determine whether these (often costly) efforts are successful or not.

To investigate this, an international team led by researchers at the University of Oxford’s Department of Biology, Wildlife Conservation Research Unit (WildCRU), and School of Geography and the Environment analysed data from almost 300 animal relocations which took place between 2007 and 2021. These spanned 22 countries in five continents, and involved 18 different carnivore species, including bears, hyaenas, big cats, and wild dogs.

Key findings:

Overall, two thirds (66%) of the relocations were successful (where the animal survived in the wild for over 6 months).
Success rates for large carnivore relocations have increased significantly since before 2007. For wild-born carnivores, success rates increased from 53% pre-2007 to 70%; and for captive-born animals, success rates doubled from 32 % in pre-2007 to 64 %.
The species with the highest success rates included maned wolves, pumas, and ocelots which had a 100% success rate. The species with the lowest success rates (around 50%) were African lions, brown hyenas, cheetahs, Iberian lynx, and wolves.
Overall, using a ‘soft release’ increased the odds of success by 2.5-fold. This involves acclimatising the animal to the new environment before it is fully released.
Releasing younger animals (particularly 1 -2 year olds), also increased success rates. This may be because younger animals have greater behavioural plasticity to adapt to new environments, and they are less likely to have developed homing behaviours.
For animals born in captivity, the success rate decreased by 1.5-fold, compared with animals born in the wild.
However, just over a third (37%) of the relocated animals were observed to find a mate and/or raise a cub in their new habitat.