How cougars and feral donkeys change desert wetlands: Novel interactions between native predators and non‐native megaherbivores shape trophic cascades in the Anthropocene

• Published in: The Journal of animal ecology 2022-12, Vol.91 (12), p.2342-2347
• Main Author: Raimundo, Rafael L. G.
• Format: Article
• Language: English
• Subjects: adaptive foraging; Animals; Anthropocene; Biodiversity; Biota; Community structure; Context; Desert animals; Ecological function; ecological naïveté; Ecology; Ecosystem; Environmental restoration; Equidae; Equus asinus; Food chains; Food webs; Herbivores; Heterogeneity; Humans; interaction rewiring; landscapes of fear; Megafauna; National parks; novel communities; Pleistocene; Pleistocene rewilding; Predation; Predator-prey interactions; Predators; Prey; Puma; Puma concolor; Spatial discrimination; Spatial heterogeneity; Structural stability; trait‐mediated indirect interactions; Wetlands
• ISSN: 0021-8790; 1365-2656
• DOI: 10.1111/1365-2656.13811

Research Highlight: Lundgren, E. J., Ramp, D., Middleton, O. S., Wooster, E. I. F., Kusch, E., Balisi, M., Ripple, W. J., Hasselerharm, C. D., Sanchez, J. N., Mills, M. & Wallach, A. D. (2022) A novel trophic cascade between cougars and feral donkeys shapes desert wetlands. Journal of Animal Ecology, (91, 2010‐2022). https://doi.org/10.1111/1365‐2656.13766. Despite being absent from most regions of the contemporary world, megafauna species dominated the dynamics of ecological communities until the late Pleistocene. Trophic rewilding is a promising approach to restoring megafauna interactions, their functional roles and the consequent trophic cascades. Unintentional rewilding with large non‐native herbivores, such as equids, offers outstanding opportunities for ecologists to understand the outcomes of using replacement species to restore the ecological functions of extinct native megafauna. In this context, it is relevant to understand the extent to which extant native predators can impose top‐down control on non‐native megaherbivores and how trophic cascades arising from novel predator–prey interactions influences biodiversity and ecosystem functions. In Death Valley National Park (United States), Lundgren et al. depict a natural experiment showing compelling evidence of native cougars overcoming ecological naïveté—that is, the mismatches between predator and prey species that do not share a common evolutionary history—and are now successfully preying on younger individuals of feral donkeys. These non‐native donkeys, whose growing wild populations threaten the native biota, became cougars' most frequent dietary item in that region. In areas with cougars, donkeys changed their spatiotemporal foraging patterns, becoming diurnal and less active. On the other hand, donkeys remain more active and forage throughout the day and night in areas without cougars. The cougar–donkey interaction triggered a behaviourally mediated trophic cascade emerging from a ‘landscape of fear’, that is, from the perception of spatial heterogeneity in predation risk by donkeys. Areas with cougars have less trampled ground, fewer donkey trails, and much more canopy cover and vegetation around water. Donkeys concentrate their activity mostly in topologically plain terrains lacking proper sites for the ambush behaviour of cougars and with more intense human presence, likely acting as a shield against the predators. Lundgren et al. present a promising model system for studying the effect