If any method is ever successful, a suggestion has been made to introduce the hybrids to a wildlife reserve in Siberia called the Pleistocene Park, but some biologists question the ethics of such recreation attempts. In addition to the technical problems, not much habitat is left that would be suitable for mammoth–elephant hybrids. Because both species are [were] social and gregarious, creating a few specimens would not be ideal. The time and resources required would be enormous, and the scientific benefits would be unclear, suggesting these resources should instead be used to preserve extant elephant species which are endangered. The ethics of using elephants as surrogate mothers in hybridisation attempts has also been questioned, as most embryos would not survive, and knowing the exact needs of a hybrid mammoth–elephant calf would be impossible.