LETTER LETTER

From Pleistocene to trophic rewilding: A wolf in sheep’s clothing

Nearly 10 y ago, we (1) critiqued the idea of large tracts to bring back communities of should stop talking about trophic or Pleis- Pleistocene rewilding (2), a misguided attempt disrupted cascades is a luxury. tocene rewilding, or its next rebadging. We to resurrect bygone ecosystems. Much has As the metaanalysis of Svenning et al. (3) were criticized (5) for drawing the analogy happened to the Earth’s biodiversity over the shows, rewilding—especially when trophic to Jurasssic Park (1). However, Svenning et al. decade since the term “Pleistocene rewilding” cascades are reinstated—can alter ecosystem (3) argue for “a framework for integrating syn- was coined, most of it bad. More than half a function, often for the better, even if the thetic biology and trophic rewilding science.” billion people have been added to the world’s mechanism is incompletely understood. How- It is time to be practical, not sensational. It is population, and ecosystems continue to be ever, using proxy species when mechanisms time to move on. degraded at an alarming rate. A sixth mass are uncertain to recreate ancient ecosystems Dustin R. Rubensteina,1 and Daniel I. extinction is underway, and poaching of could have many unintended consequences Rubensteinb megafauna has increased across sub-Saharan (1). Simply repackaging Pleistocene rewilding Africa. Unfortunately, one thing that has not as trophic rewilding does nothing to change aDepartment of Ecology, Evolution and happened is any serious attempt to scientifically this fact. Without good science, such large- Environmental Biology, Columbia University, study Pleistocene rewilding. Despite a number scale reintroductions could be as untested as New York, NY 10027; and bDepartment of of publicized Pleistocene rewilding projects dumping iron into the sea, or placing particles Ecology and Evolutionary Biology, Princeton (Oostvaardersplassen in The Netherlands and in the sky to attenuate the effects of climate University, Princeton, NJ 08544 Pleistocene Park in Siberia), we have yet to see change. We cannot afford to co-opt good sci- anyquantitativedataconcerningtheimpactsof ence (research on trophic cascades) to justify

megafauna reintroductions. bad science (Pleistocene rewilding) at a time 1 Rubenstein DR, Rubenstein DI, Sherman PW, Gavin TA (2006) Svenning et al. (3) again revive the Pleistocene when species are in peril. Pleistocene park: Does re-wilding North America represent rewilding debate. No longer calling it Pleisto- There is no doubt that today’s ecosystems sound conservation for the 21st century? Biol Conserv 132: 232–238. cene rewilding, they repackage the sensational are different from those of 10,000 y ago. 2 Donlan J, et al. (2005) Re-wilding North America. Nature into something more palatable: “trophic However, they are also quite different from 436(7053):913–914. ”“ ” “ 3 Svenning J-C, et al. (2015) Science for a wilder Anthropocene: rewilding. Trophic refers to a trophic the ecosystems of just 10 y ago, when rhinoc- Synthesis and future directions for trophic rewilding research. Proc cascade”—when the removal of a top predator eros and elephant poaching in Africa seemed Natl Acad Sci USA, 10.1073/pnas.1502556112. or herbivore has indirect and cascading effects under control. In another 10 y, there may be 4 Searchinger TD, et al. (2015) High carbon and biodiversity costs from converting Africa’s wet savannahs to cropland. Nat Clim on lower tropic levels. Over the past decade, no rhinoceros left. Rather than continuing to Change 5:481–486. there has been much scientific study of trophic promote the sensational by repackaging a failed 5 Donlan CJ (2007) Restoring America’s big, wild animals. Sci Am cascades, including those created by the re- conservation strategy in shiny new clothing, 296(6):70–77. moval of megafauna. However, even these we should direct our efforts toward preserv- studies recognize that ecosystems are no ing the ecosystems and wildlife that remain. Author contributions: D.R.R. and D.I.R. wrote the paper. longer pristine, especially those harboring We should focus on ways to feed the millions The authors declare no conflict of interest, though they are related. ’ large mammals. Today s reality is that wild- of new mouths appearing each year with- 1To whom correspondence should be addressed. Email: dr2497@ life and people must coexist. Setting aside out destroying more biodiversity (4). We columbia.edu.

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