Despite the significant benefits they have and will continue to provide, the traditional approaches of protected areas and in situ conservation management alone cannot shield vulnerable species from the growing threats they face. Habitat loss and fragmentation, over-exploitation, invasive species, pollution and climate change are all problems that have grown as the world’s human population increases and expands.
This is why we have to consider more risky and intensive conservation options such as translocations: the intentional movement and release of endangered creatures for conservation benefit.
There is a spectrum of conservation translocations. Reinforcing existing threatened populations by “topping up” with individuals taken from other areas where they thrive increases numbers and genetic diversity, which improves their ability to withstand change and disease. Reintroductions are attempts to restore populations after they have gone locally extinct.
More risky and uncertain is the controversial technique of conservation introductions. The two techniques are assisted colonisation, in which species are moved from their native range where they are threatened to somewhere they have never naturally inhabited in order to preserve them, and ecological replacements, where a suitable substitute species is introduced to perform the ecological role of one that has become extinct.
Understandably, given the history of terrible consequences from ill-planned species introductions – perhaps most obvious in Australasia – these are seen as extreme methods and not actions to be undertaken lightly. The key challenge is therefore to understand and manage the risks involved. It’s also necessary to have an exit strategy – to be sure you can reverse the releases if things do not go as planned. For threatened species at low-population densities released into confined areas of habitat this would be feasible.
There are already great gains being made using conservation translocations of all kinds. Reintroductions are restoring whole suites of species – mostly mammals and birds, but increasingly plants, reptiles, amphibians, fish and invertebrates are being released into suitable areas. For example some 55 species of birds have been translocated in more than 1,000 projects, and populations of reptiles and amphibians are now also being restored in New Zealand.
Assisted colonisation is also used in Australia and New Zealand, where native species have been moved beyond their normal range in order to protect them from the threats posed by exotic mammals. And on islands in the Indian Ocean giant tortoises have been introduced as ecological replacements for extinct species, to restore the seed dispersal and vegetation grazing functions that had been lost.
Early conservation translocations have had low success rates, but as techniques are developed and refined, results are getting better and we are seeing an exponential increase in the number of translocation projects worldwide. There is however still a bias towards the more charismatic species of birds and mammals, but this is slowly changing.
But there is a major challenge facing conservation translocations. If we are seeking to restore wildlife populations we must ask the question: restore to what? What is the target state, the ideal we are seeking? In the New World, perhaps in the past the answer would have been to restore the environmental balance to how things were before (European) human settlement. But there is a growing awareness that pre-European landscapes were not the pristine wilderness of our imagination. It is unrealistic to seek such ideals in the anthropocene, our modern human-dominated world.
We need to move away from the idea of having free-ranging wild species roaming over large areas of wilderness untouched by human influences. We must understand now that virtually every ecosystem on earth has been modified by humans, and some of those modifications go back to prehistory. An obvious example is the extinction of megafauna species or massive deforestation across Europe after the first arrival of humans in the Pleistocene period, many tens of thousands of years ago.
We need instead to think about how we can restore “wildness” rather than the unobtainable “wilderness”. By that I mean finding a place for wildlife to persist in areas alongside humans, both for their sake and ours. Too quickly we can lose a sense of how much we have lost, with each generation handed a natural world to grow up in that is progressively more impoverished than the last. Species restorations give people a chance to experience, appreciate and learn to cherish their natural heritage.