Large Predators’ Habitat Expanding Into Unexpected Territories Is A Complicated Matter

A paper published Monday in the journal Current Biology sheds light on large predators in various parts of the world moving into habitats they had once occupied, before human activity pushed them into small geographical areas and drove them to near-extinction. But it may be somewhat premature to celebrate this development as a definite conservation success.

A team of researchers, led by Duke University’s Brian Silliman, published a paper titled “Are the ghosts of nature’s past haunting ecology today?” in which they cite various examples of large animals moving outside the areas they were known to traditionally inhabit, and using historical data, they said “rather than occupying them for the first time… many of these animals are in fact recolonizing ecosystems.”

The paper says: “Sea otters along the northeast Pacific coast have expanded into estuarine marshes and seagrasses, and alligators on the southeast US coast have expanded into saltwater ecosystems, habitats presently thought beyond their niche space. There is also evidence that seals have expanded into subtropical climates, mountain lions into grasslands, orangutans into disturbed forests and wolves into coastal marine ecosystems.”

According to Silliman, a large part of this reclamation of their old territories by these species is a consequence of conservation, and that it goes against the widely-held belief that many of these animals lived in specific habitats because they were specialized to live in those particular ecosystems.

“We can no longer chock up [sic] a large alligator on a beach or coral reef as an aberrant sighting. It’s not an outlier or short-term blip. It’s the old norm, the way it used to be before we pushed these species onto their last legs in hard-to-reach refuges. Now, they are returning,” he said in a statement. “Now that they are rebounding, they’re surprising us by demonstrating how adaptable and cosmopolitan they really are.”

While it cannot be denied that conservation has a large role to play in the spread of these species to areas they had formerly occupied, it cannot be seen as an unquestionable success of conservation itself. For instance, just because a large predator species has moved from its traditional habitat to a newer one does not mean that the entire ecosystem it was a part of moves with it. And there are various other species, large and small, who live in that ecosystem, which continues to suffer as a consequence of human activity.

Further, expansion into newer habitats, especially those closer to human habitations, are fraught with danger, even if humans did not directly and intentionally present that danger. For instance, there are live wires that can electrocute animals, or plastic and toxic objects they could unwittingly consume.

Also, a large predator entering a new territory would upset the ecological balance that already existed there, maybe by displacing the existing top predator in that area, which would then face survival issues of its own.

While there is no doubt the study shows an important success story as a result of conservation measures, it should not be seen as enough done.