Living on the edge: Building Noah's Ark
Part four of the 'Living on the Edge'series looks at how rising human population, tourism and development is affecting wildlife on barrier islands.
The goal was simple. Protect sea turtles by raising them in captivity during their most vulnerable stage as hatchlings, then release them back into the ocean.
“The idea was if you could raise a hatchling to be about two years old, making it the size of a frisbee, and then release it into the wild, instead of most of them being eaten, maybe most of them will survive,” said David Godfrey, executive director of Gainesville-based Sea Turtle Conservancy.
That was the theory. It was a complete and utter failure.
As threats such as climate change decimate animal habitats on barrier islands and other vulnerable areas, humans question if we should intervene. Wildlife relocation, also known as assisted migration or managed relocation, involves moving a species to a new environment, and often requires breeding wild animals within captivity before they are released. While there have been success stories such as saving the California condor from extinction, other species become an invasive nuisance or struggle to adapt to an unfamiliar ecosystem.
The sea turtle researchers, then working in Costa Rica, discovered that when hatchlings drift around the ocean, they are developing a very clear map of the world. They use this mental map to migrate, to find their way back to nesting beaches and to fulfill their ecological role. When young turtles were released from captivity, they lost their ability to survive in the wild.
“After over six decades of trial and error, we’ve found that the thing that works is reducing threats as best you can and then just letting turtles be themselves,” Godfrey said.
Florida’s archipelagos and barrier islands are home to a rich variety of animals that are especially vulnerable to rising seas. When sandbars break away from the mainland and become isolated islands, wildlife living there adapt into specialized subspecies. Islands also host essential nesting sites for turtles and birds.
“Florida’s islands are really special in the sense of wildlife. Their adaptions to living on those islands are very unique,” said Richard O’Connor, Sea Grant extension agent for Escambia County in the Florida Panhandle. “Many of our islands have mice that live on them, what we’d call beach mice. There are five different species in the state of Florida and four of those are actually listed as endangered, because they only exist on that island.”
Only 300 to 400 Perdido Key beach mice remain. The beach mice carry out vital ecological functions such as dispersing seeds, which vegetates islands and slows the movement of sandbars.
“Anybody interested in developing the sandbars, they don’t want the mice to go anywhere, if you have a house on them. The mice keep the dune system in place,” O’Connor said. “They play a pretty specific role in what they do.”
But islands are epicenters of extinction. An estimated 75 percent of mammal, reptile, bird and amphibian extinctions play out on islands.
The infamous dodo bird once resided on the island of Mauritius, 500 miles off the coast of Madagascar. Living on an island with no natural predators, the bird became flightless as well as fearless. When humans discovered the dodo in the late 1600s, the eccentric island species quickly went extinct.
“A lot of invasive species get to an island, and then the animals there, we call them naïve —– they don’t know how to protect themselves from predators,” conservation scientist Sarah Skikne said. “So the local species will be devastated by a new predator or a new herbivore.”
Scientists have found that invasive species have played a role in 86% of island extinctions. Once humans introduce non-native animals such as rats or domestic cats, carefully balanced ecosystems begin to crumble. A seemingly simple study involving releasing a beetle to combat an invasive plant can involve up to 10 years of testing to be approved.
“An island is like an upside-down lake because it’s surrounded by the ocean, and the lake is isolated because it’s surrounded by land, and it creates another kind of similar situation where you have unique species that are easily threatened,” Skikne said.
Wildlife relocation is one option that could protect Florida’s island species from being lost to extinction. “Usually, we are thinking about restoring places or preserving things the way they used to be, but when the climate is changing, it’s changing what can live where,” said Jessica Hellmann, executive director of the University of Minnesota’s Institute on the Environment. Hellmann, along with Sikne, were co-authors on a major wildlife climate adaptation study designed to guide the National Park Service on how to evaluate the risks associated with wildlife relocation.
“Climate change sort of changes our whole orientation between a way in which people and nature are interconnected,” Hellmann said.
The study offers five critical points to evaluate when deciding on managed relocation. They include ecological justification; how feasible it is to carry out the relocation; the wildlife-management priority; whether the ecological risk is acceptable; and if society will deem the translocation acceptable.
“It really allows us to think about what we want these ecosystems to look like, what constitutes a healthy ecosystem and what are human priorities in conservation,” Hellmann said.
When translocation is worth the risk, scientists still grapple with figuring out when a species should be relocated. There needs to be a large enough pool of genetically diverse individuals to choose from.
“Are you trying to move them in advance of something or are you trying to move them in response to something?” Skikne said. “It’s a moving target. So when do you shoot the gun?”
Florida’s charismatic Key deer are threatened by sea level rise consuming their habitat. This tiny subspecies of white-tailed deer is endangered, with only 800 animals left in the wild.
“They’ve evolved in this marine environment that’s almost a hundred miles out in the middle of the ocean, on this string of islands known as the Florida Keys,” said Key deer expert Roel Lopez, a wildlife ecologist at Texas A&M University. “What makes them unique is that they’re a product of this very unique environment. So if that environment disappears, or is limited, it’s going to make translocation that much harder to look at.”
Key deer have adaptations different from their cousins on the mainland, such as stronger swimming skills and a higher tolerance for drinking brackish water. If relocated, they would have to compete with their larger relatives for resources, possibly causing overconsumption of valuable plants.
“There isn’t a really viable managed relocation option for them because as soon as they’re not island deer, they’ve sort of lost what it is that made them distinct in the first place,” Hellmann said. “They’re an excellent case study because you can see how the islands would be threatened by climate change, but on the other hand there might be a certain amount of climate change where moving Key deer just doesn’t seem like it should be a priority if they can’t be in the Keys anymore.”
The 1995 reintroduction of gray wolves into Yellowstone National Park is applauded as a prime example of conservation translocation. The wolves were driven to extinction within the region by humans nearly 100 years prior.
“There were very serious, very explicit series of studies and a very clear conservation objective. It was not just the wolves that were looking to be reintroduced, it was the role of the wolves in the ecosystem to achieve a series of conservation outcomes,” Hellmann said. “So I would say not only do you have the beauty of the wolf, but the very clear intention about what function in the ecosystem the wolf plays and why it’s desirable.”
Certain species pose a higher risk when being transported to a new environment, especially predators or freshwater species being moved into a different water basin. Despite extensive research on projected outcomes, it’s always a gamble on how the relocated species will adapt.
“We may feel like it’s a great, important thing to intervene in the reproductive process of an animal. For some period of years we may do a great job, because we’ve destroyed their habitat so much that they simply can’t survive on their own,” Godfrey said. “So we manipulate them in some way. We bring them into hatcheries, we grow them in incubation tanks. At some point we’re going to become tired of doing that. And is it a hundred years later we’re going to get tired of it? Is it a thousand years later we’re going to get tired of it? It’s not going to be a priority at some point.”
Advocates are urging politicians to pass legislation that will slow climate change, and to save wildlife habitats before it’s too late. A majority of Americans, too, want to see greater action from the government on climate change.
“There’s still so much work to do,” Hellmann said. The key is to “work towards finding and implementing those solutions,” she said. “You can’t just throw your hands in the air and quit.”
From coyotes to gopher tortoises and beach mice, many animals make their home on Florida’s barrier islands. Humans helped draw animals to these fragile habitats. Now, we’re squeezing them out. Read the previous article in the ‘Living on the Edge’ series here.