Climate change is altering the way some scientists are trying to save endangered plant and animal species from extinction.
For nearly 100 years, conservationists have focused preservation efforts on maintaining species' historical ranges and reintroducing captive-bred species to boost dwindling populations. Now, some scientists are experimenting with a new approach.
"What's changed over the years is we introduce [species] into areas where they have never been before," said Philip Seddon an associate zoology professor at Otago University in New Zealand. "It's acknowledging that there are no pristine habitats, it's not feasible to have them locked away from people."
The approach is called conservation translocation. Scientists move endangered species that are unable to shift their habitats on their own into new locations. That can mean moving species into areas closer to humans. Translocation is also used to correct an ecological void created by the extinction of another species, said Seddon, the lead author of a paper on translocation published in the journal Science last month.
As temperatures and sea levels rise, endangered species are especially vulnerable to losing habitat. An estimated 20 to 30 percent of the world's species will be at risk for extinction if global temperatures rise 2 to 3 degrees Celsius above preindustrialized levels in the next century, according to a report by the Intergovernmental Panel on Climate Change (IPCC).
Over the last six years, interest in translocating endangered plant and animal species into new habitats has exploded. More than 75 percent of 195 scientific articles on the subject were published after 2008, according to a study published last year in the Annals of the New York Academy of Sciences. The co-author of the study, Mark Schwartz, attributed the interest to the recent compelling evidence that climate change is causing species extinction.
Most face immediate threats from habitat loss, competition with invasive species and exploitation. Translocation could also remove endangered species from these threats as well, said Schwartz, who is the director of the John Muir Institute of the Environment at the University of California, Davis.
With climate change, Schwartz said, "People see something they can do [to stop extinction], and it's appealing."
Fla. tree moves to N.C.
Despite the buzz about species translocation, it is highly controversial. On one side are conservationists who prioritize saving endangered species. On the other are biologists who envision the introduced species becoming invasive in their new habitats.
The Torreya Guardians -- a grass-roots group determined to save the Torreya taxifolia, also known as the Florida torreya -- belong to the pro-translocation camp. The tree once populated the forests of the southeastern United States.
Today, the critically endangered evergreen tree grows in a small corner of the Florida Panhandle, since it was devastated by fungal infections and logging. The Torreya Guardians are planting seedlings in parts of North Carolina, where they believe the tree will be better able to withstand the effects of climate change.
Lee Barnes is one of the founding members of the Torreya Guardians and an ecologist by training. He said the group is an example of a low-risk effort to save "a tree that's survived the test of time."
The Florida torreya reaches maturity after 10 to 15 years, there is little chance of it becoming invasive, and the seeds are cheap and easy to transport, he said.
"You can't save the world without saving all the pieces," Barnes said when asked why preserving the tree was important.
Barnes said his group provides just one possible model, though its way was not necessarily the best or most efficient. Schwartz agreed the risks of planting the Florida torreya around the country were probably minimal. However, he warned that the effects may be worse with other species. In the United States, there is no regulation on bringing native plant species to different parts of the country, possibly allowing them to become invasive, he said.
"The ethically responsible thing to do is at least to bring an exit strategy," Schwartz said. "If you brought lions to an area, you could get them out if they caused problems, though even that would be difficult. But how would you get rid of a plant? Historically, we haven't had success getting rid of plants once they are established."
Filling an ecological void
Translocation is not only a way to preserve species, it can also be used to restore ecological function when important species in an ecosystem go extinct.
One example is the introduction of the Aldabra giant tortoise, Aldabrachelys gigantea, to Mauritian offshore islands. The giant tortoises replaced the grazing and seed-dispersal roles of the now-extinct Mauritian Cylindraspis species. Similar projects are already happening or are planned in Madagascar, the Galapagos, the Mascarenes, Seychelles and the Caribbean.
A number of conservationists agree that translocating top predators is the most valuable strategy because they play key roles within ecosystems. Some groups have explored reintroducing wolverines, lynxes and wolves to some areas of Europe, in part to control deer populations, Seddon said. However, managing predator translocation is the most expensive and complicated.
Conservationists not only have to pay for safely breeding, releasing and monitoring the predators, but also for damage the introduced species cause, according to updated translocation guidelines published by the International Union for the Conservation of Nature (IUCN).
Because very little untouched land remains, translocation of these species would also mean that top predators need to be introduced into areas where they would be relatively close to human populations, Seddon said. It's an idea he would like the general public to become more comfortable with, though he acknowledged that many people are frightened of possible attacks on people and domestic animals.
Helplessness and nostalgia
Species that are particularly vulnerable tend to be those in specialized habitats, surrounded by either geographical or man-made barriers. They may also have limited genetic capability to adapt to new environments, according to conservationists.
"Many of the threatened species are just the kind of species that can't [move] on their own," said Chris Thomas, a professor in the biology department at the University of York in the United Kingdom.
One example is the now-extinct golden toad that was once common in the high-altitude Costa Rican cloud forest of Monteverde. The toads would not have survived a migration to a new high-altitude habitat, but there is a chance they could have been saved if humans had assisted them, Thomas said.
Species that are less specialized are able to adapt more to changing climates.
"We have very strong evidence that species are shifting their distribution," Thomas said. In many cases, plants and animals are moving to higher elevation and toward the poles where the climate is cooler, suggesting that when they are able to, species are responding to climate change.
In Thomas' opinion, criticism of translocation is "driven by nostalgia, or a feeling that there was a romanticized period in the past when somehow humanity and nature were in balance."
In reality, he said, humans have continually manipulated other species, and the populations themselves are always changing. Even if we could identify a time when humans were more in sync with the natural world, we wouldn't be able to achieve it.
Instead, energy should be focused on at least trying to save endangered species and treat them as "innocent until proven guilty," Thomas said.
Vulnerability that is growing
In 2013, the IUCN, the oldest international conservation organization, compiled a detailed report outlining which endangered species of birds, amphibians and corals were likely to be the most at risk from rising global temperatures and changing weather patterns.
It found that 6 to 9 percent of endangered bird species, 11 to 15 percent of amphibians and 6 to 9 percent of corals were considered highly vulnerable to climate change and would be threatened with a greater risk of extinction if current climate trends continue.
The IUCN report was the first to look at the effects of climate change on various species on a global scale, said the study's lead author, Wendy Foden.
A team of more than 30 experts identified nearly 100 biological, ecological, physiological and environmental traits that contributed to species adaptability.
The report also listed a number of species that were very highly vulnerable to climate but had not previously been considered endangered, including 17 to 41 percent of bird species, 11 to 29 percent of amphibians and 9 to 22 percent of corals.