Extinction as predator removal: Intraguild competitive cascades, mesopredator release, and a paleoecological perspective for conservation biology

A conceptual model of one representative North American predator guild—the canids—provides a tool for the management of carnivores and their prey and suggests: (1) that mesopredator release in North America, rather than representing a recent ecological novelty, was typical during the Pleistocene and (2) that ecological restoration efforts aimed at a Pleistocene benchmark could in some respects benefit from excluding rather than introducing the largest predators. More generally, the model suggests (3) that restoration efforts aimed at a pre-European North American benchmark would benefit threatened mesopredator prey species, while a Pleistocene restoration strategy would provide them with little or no advantage over current conditions. These conclusions emphasize the value of a paleoecological perspective in conservation biology and the need for caution in restoration efforts, particularly those that call for the introduction of Old World megafauna as analogs for extinct Pleistocene species. Since the major conservation challenge for the foreseeable future will continue to be the limited availability of wildlife habitat, priority should be given to protecting extant North American species and understanding their ecology. Such a prioritization will inform the discussion about whether a pre-Columbian or pre-human Pleistocene standard is preferable for North American restoration. Megafaunal introductions, should they ever be deemed desirable, would necessarily follow this more fundamental ecological research.