Want good conservation? Treat animals like trees, and 'plant' them in new areas

Much of modern conservation is characterised by an unspoken philosophy of “build it and they will come”. If we plant the trees and restore the habitat, the animals will return. Right?

Over the past couple of decades this philosophy, nicknamed the Field of Dreams hypothesis, had led many conservation practitioners to focus purely on plants. Then they simply cross their fingers and hope that other elements of the original ecosystem will eventually come back, just like the crowds who come to watch the baseball game and save the farm from ruin in the movie.

Unfortunately, we now know that this hypothesis only applies in some circumstances, primarily involving mobile animals that can colonise these recreated habitats from afar. So while conventional restoration may work for birds, bats and butterflies, what happens to everything else?

For many animals that are unable or unwilling to colonise isolated habitat patches, the outlook is doubly grim. To begin with, as they are unable to move into recreated and regenerated habitats, they are effectively stranded. Then, in those areas where populations persist, crowding increases and survival diminishes as scant resources become stretched.

This can lead to a paradoxical situation in which increasing amounts of high-quality habitat remain unoccupied, while occupied sites become progressively worse as their resources dwindle. It is a recipe for the extinction of local populations, which in turn brings the entire species closer to dying out completely.

Saving species while they’re still healthy

Our solution to this predicament is to apply the adage that prevention is better than cure. By moving common animals into unoccupied habitat patches well before their population health begins to decline, we can help to ensure that they stay common.

The idea of moving animals around isn’t new. But it has traditionally focused only on vulnerable, threatened and endangered species, often using expensive interventions with captive-raised individuals, and carried out by highly trained staff inside pristine reserves. These “species reintroductions” are seen as a last-ditch bid to avert imminent extinction, rather than as a way to keep populations healthy.

A fat-tailed dunnart, one of many native marsupials that would benefit from a helping hand.David M Watson, Author provided

Instead of reintroducing captive-bred animals into the wild, we propose moving already-wild animals from populated areas into other suitable areas of habitat where they don’t currently live. As well as alleviating pressure in those areas where the species remain, this will help the species to disperse and allow its population to increase.

We call our proposal “wildlife restoration”, because it helps species overcome the problems of habitat fragmentation, much as forest restoration does the same thing for trees.

Species and cities

While the larger habitat patches in agricultural landscapes are likely to yield more successful outcomes in terms of animal populations, we see urban landscapes as ideal places for wildlife restoration. Our cities and suburban centres are not randomly located; they occupy areas with fertile soil and reliable rainfall, and because of this they often overlap with areas of high biodiversity.

Far from being barren concrete wastelands, urban landscapes can support a surprising variety of wildlife, but only if those animals can find the right habitats. Once we start moving animals around to new areas, we can see what strategies will work and what won’t, and local communities can become involved and learn as they go.

If this sounds like meddling with nature, well, it is. But it is mindful meddling with a very clear purpose, unlike the changes wrought on natural systems by accident over the years. Exotic animals have become invasive pests, garden plants have spread and dominated bushland; household and agricultural chemicals have poisoned entire food webs.

Candidate critters

So, what kind of animals are we talking about? Familiar, widespread animals like blue-tongue lizards and sugar gliders in Australia, common shrews and fire salamanders in Europe, stinkpot turtles and bumblebees in North America.

Candidates for restoration need to be sufficiently abundant in areas close to potential release sites that the removal of individuals has no negative effect on the population. There also needs to be a careful assessment of the risks and potential threats – simple common sense would rule out introducing venomous snakes to an urban park, even though it might make great ecological sense!

Urban landscapes contain lots of high-quality habitats where animals might be released: cemeteries, golf courses, easements and buffers around airports, landfills and industrial sites, parks, established gardens, school grounds and university campuses. Many agricultural landscapes also contain vegetated hilltops, gullies, roadside strips and other useful habitat pockets.

Beyond that, rehabilitated mines or industrial sites, freeway buffer strips, or even green roofs or street trees could offer useful places for wildlife restoration.

The ultimate aim is to play an active role in creating a future with more wildlife and functioning ecosystems in the places where we live and farm. This future complements the idea of rewilding, but at the scale of communities rather than continents. We need to continue revegetating and building habitats everywhere we live, and we must also recognise that many animals need a helping hand.

David M Watson receives funding from the Australian Research Council.

Maggie J. Watson receives funding from Conservation Evidence.