Pleistocene Rewilding: An Optimistic Agenda for Twenty‐First Century Conservation

Abstract

Large vertebrates are strong interactors in food webs, yet they were lost from most ecosystems after the dispersal of modern humans from Africa and Eurasia. We call for restoration of missing ecological functions and evolutionary potential of lost North American megafauna using extant conspecifics and related taxa. We refer to this restoration as Pleistocene rewilding; it is conceived as carefully managed ecosystem manipulations whereby costs and benefits are objectively addressed on a case-by-case and locality-by-locality basis. Pleistocene rewilding would deliberately promote large, long-lived species over pest and weed assemblages, facilitate the persistence and ecological effectiveness of megafauna on a global scale, and broaden the underlying premise of conservation from managing extinction to encompass restoring ecological and evolutionary processes. Pleistocene rewilding can begin immediately with species such as Bolson tortoises and feral horses and continue through the coming decades with elephants and Holarctic lions. Our exemplar taxa would contribute biological, economic, and cultural benefits to North America. Owners of large tracts of private land in the central and western United States could be the first to implement this restoration. Risks of Pleistocene rewilding include the possibility of altered disease ecology and associated human health implications, as well as unexpected ecological and sociopolitical consequences of reintroductions. Establishment of programs to monitor suites of species interactions and their consequences for biodiversity and ecosystem health will be a significant challenge. Secure fencing would be a major economic cost, and social challenges will include acceptance of predation as an overriding natural process and the incorporation of pre-Columbian ecological frameworks into conservation strategies.

Diversity and depletions in continental carnivore guilds: implications for prioritizing global carnivore conservation

“…Limited attention has been given to the effects of carnivore conservation on the ecosystem function of predator guilds (e.g. Dalerum et al 2008), except the bold suggestion to repopulate North America with non-native species to restore ecologically functional relationships among large vertebrates (Donlan et al 2006). Furthermore, although regional plans for carnivore conservation and restoration have been proposed (Carroll et al 2001;Mills et al 2001;Enserink & Vogel 2006), there is no current framework to make global prioritizations for such efforts.…”

What constitutes a ‘native’ species? Insights from the Quaternary faunal record

“…Such programmes may aim either to restore former regional species composition, or former ecosystem processes such as rooting of forest vegetation by boars. Indeed, the latter is often cited as the goal of many so-called 'rewilding' projects concerned with the effects of past human-caused removal of former keystone species (Zimov, 2005;Donlan et al, 2006;Griffiths et al, 2011), but which may be achieved using extant ecological substitutes rather than now-extinct native species.…”

The Rise and Fall of Biotic Nativeness: A Historical Perspective

“…Favouring natives over aliens as they propose would justify returning Europe to a pre -Neolithic condition, and the Americas to a pre -Columbian one. Such proposals (for example Popper & Popper 1987 ;Donlan et al 2006 ) have achieved notoriety but little traction. However, there are situations where conservation biologists have espoused a more limited version of such a view and attempted its implementation.…”