In this case, the desirable approach to save the endangered species of wild cat would be the in situ approach.

In situ conservation involves protecting and preserving the species within its natural habitat. This approach is desirable because it allows the species to continue its natural ecological processes and interactions with other species. By conserving the natural habitat, it helps maintain the integrity of the ecosystem and promotes the survival of a variety of species, not just the endangered wild cat.

On the other hand, ex situ conservation involves removing the endangered species from its natural habitat and placing it in a controlled environment, such as a zoo, botanical garden, or captive breeding program. While ex situ conservation can provide immediate protection for the species, it may not be as effective in the long term. In captive environments, the species may face challenges such as limited space, social interactions, and reduced genetic diversity. Additionally, ex situ conservation does not address the underlying causes that lead to the species' decline in the first place, such as habitat loss or illegal hunting.

By focusing on in situ conservation, efforts can be made to protect and restore the natural habitat of the wild cat. This may include initiatives such as creating protected areas, implementing sustainable land-use practices, educating local communities about the importance of conservation, and enforcing strict regulations against illegal hunting or trade. In situ conservation not only helps the endangered species but also contributes to the preservation of biodiversity and the overall health of the ecosystem.

Overall, in situ conservation is a desirable approach in this case as it allows for the long-term survival and recovery of the endangered wild cat species within their natural habitat while also addressing the broader ecosystem conservation needs.