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Sperm whales live in the remote open ocean. Scientists have known for years that this is what sperm whales live in. The U.S. government’s 2010 recovery plan for sperm whales characterizes their range as “generally offshore.” A 2016 study of their Australian range describes the whales as foraging in “deep offshore areas of the world’s oceans.” This understanding goes way back. In Moby-Dick, published in 1851, the whaling ship Pequod chases sperm whales far from shore, days from port.
But this doesn’t mean that sperm whales want to limit themselves to open ocean. A new study that looks at records from the heyday of “Yankee whaling“–1792 to 1912–found that sperm whales used to hang out much closer to the coast. Although sperm whales require deep water for their food hunt, the area they chose to live in was closer to the coast. Tom B. Letessier (lead author of the study, and marine biologist with the Zoological Society of London), told me that sperm whales tend to seek out what is easily accessible. Those remote ocean habitats, in other words, aren’t the only places where sperm whales have always lived; they are the last hideouts of the whales that survived centuries of whaling that reduced their population by more than half. (The study focused on the Western Indian Ocean, but the pattern is likely the same around the world, Letessier said. )
A generation after the end of significant whaling in 1986, the ocean’s giants are still in hiding. If humans could stop hitting them with ship or trapping them in nets, then there shouldn’t be any reason for sperm whales to recolonize those areas. In places where the sea gets deep close to shore, like Monterey Bay, California, you could probably see them spout from the beach.
Sperm whales aren’t the only species for which our range maps might be all wrong. Experts told me that many species have a range that is not only determined by their climate tolerance, availability of food or distance from humans. Are we trying to protect animals from the wrong places? If our ideas about where species belong are based on relict populations that live as far from humans as possible, we risk boxing wildlife into limited, resource-poor areas. In a world where animals are already dealing with rising temperatures, hunting, fishing, and the commandeering of ever-larger chunks of their homes for agriculture and development, trying to conserve them in subpar habitat seems like a terrible idea.
Species conservation often relies on the idea of a “native range,” a somewhat amorphous concept that roughly means the area where a species normally or naturally occurs–not including any places where humans brought it. This is the most suitable habitat for any species. Protected areas may be built around it. It may be reintroduced to try and repopulate. And if species stray outside it, they may be considered “invasive” and possibly even targeted for removal. But, Brian Silliman from Duke University said that “using the notion of native range restricts us.” Silliman, who wasn’t involved in the sperm-whale study, believes that many maps of native ranges are off–and not by just a little bit. I was presented with an instance he had witnessed in an extremely visceral manner. He almost got eaten by an alligator while collecting data on snails at a barrier island off the coast of Georgia. He was collecting data on snails on a barrier island off the coast of Georgia and was ambushed by a 12-foot gator, a species not known for hanging out in or near the ocean. Silliman found himself pinned under the gator and fought back, punching its sides until it got spooked and fled. “Turns out alligators are all over the southeast shore in marine environments,” he told me. We didn’t know that gators can thrive at the beach. Because we had killed all the beach gators.
The same phenomenon has occurred with many animals. Calling a cougar a “mountain lion” suggests that it prefers the mountains, but Silliman says they used to prowl the lowlands, too, where there were more prey. He said, “There is no mountain lion.” We just invented that. “That’s where it was last seen.” Conservationists believed that sea otters would be able to live in the ocean when they tried to restore them to their natural habitat. But reintroduced otter populations are flourishing in salt marshes and seagrass beds, where they are protected from orcas and sharks.
Silliman thinks our assumed native ranges for many species are just a quarter of the total historical range. And in many cases, the “native range” that animals occupy now might be places where they can barely survive–because they are the harsh, marginal places that humans don’t want to go: steep slopes, high mountains, polar seas. Conservators may not be able to encourage animals to reproduce and live in the best possible environments, so they might end up wasting their resources.
Calling for conservation to take into account the “full” or “true” range of a species seems sensible, but nailing down what that range is gets complicated fast. It is possible to look back hundreds of years in order to determine where an animal lived “naturally”, but that can be difficult for some species. In others, it might mean turning back the clock thousands of years. One analysis of ancient-panda diets suggests that their mountain bamboo forests are not their ideal habitat; it calls for new panda protected areas in the lowlands, where their diets could be more varied. It would be possible to return to the same area they lived thousands of years before.
North America’s native ranges are defined as the places where animals lived prior to humans arriving and influencing ecosystems. Your maps will be from North America’s Pleistocene. It would not be possible to recreate a different world, such as a Midwest covered with glacial ice and populated by mammoths or giant ground sloths. Elk arrived from Eurasia only 15,000 years ago. The cattle egret arrived in North America, on its own wing power, in the mid-20th century. Ranges are also definitely going to keep changing in the future, especially as the climate warms. Are new areas that are colonized by plants seeking lower temperatures considered part of the native range?
Conservationists have typically focused on protecting and restoring species in their native range only, but if that range is often misunderstood and fundamentally dynamic, creating a single definitive map for each species may remain elusive. Although this is a minor view that I support, it does make sense because of its logic and coherence.
Instead of asking “Where does this species belong?” some conservationists are beginning to ask something more like “Where can this species thrive without causing unwanted effects?” They are looking at areas where the species can do well today–and in a warmer tomorrow. These areas are very likely to overlap significantly with a more traditionally defined native range, but they could include areas the species has never been before–or at least not in human memory. One broadly accepted approach that moves away from strict fealty to native ranges is to welcome new arrivals moving with warming as climate “refugees,” rather than labeling them as “invasive.” Another more controversial tactic is to physically move species to suitable habitats as the climate makes former habitats inappropriate, a practice called “assisted colonization.”
Learning about the environmental history of places and species will still be important, even if we move away from basing our conservation strategies on native ranges. Knowing that sperm whales love to be near the coast can help us imagine where we might find them flourishing in the future. It also helps us draw the boundaries of marine protected areas.
Given how much humans have changed the world, we are unlikely to be able to return everything to the way it used to be, even if we could agree on how far back to go. We can make a world in which wild animals thrive and are plentiful. The good news is they will bounce back if you don’t kill them and protect their habitats. Wolves recolonized Western Europe, and humpback whales and some populations of green sea turtles have seen population increases of more than 1,000 percent since being listed as endangered. Wild animals can return.
When and if animals recolonize ancient habitats or expand to new habitats that are now quite close to human spaces, there are likely to be some tension. Researchers are already documenting an uptick in human-wildlife contact as humans sprawl into wildlands, as animals move in response to climate, and as conservation succeeds in bringing species back to old haunts. While coexistence has its risks and benefits, it can also lead to conflict, loss of crops, and other issues. You might find it surprising how coexistence can be so beneficial.
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