Predator interactions, mesopredator release and biodiversity conservation

Abstract

There is growing recognition of the important roles played by predators in regulating ecosystems and sustaining biodiversity. Much attention has focused on the consequences of predator-regulation of herbivore populations, and associated trophic cascades. However apex predators may also control smaller ÔmesopredatorsÕ through intraguild interactions. Removal of apex predators can result in changes to intraguild interactions and outbreaks of mesopredators (Ômesopredator releaseÕ), leading in turn to increased predation on smaller prey. Here we provide a review and synthesis of studies of predator interactions, mesopredator release and their impacts on biodiversity. Mesopredator suppression by apex predators is widespread geographically and taxonomically. Apex predators suppress mesopredators both by killing them, or instilling fear, which motivates changes in behaviour and habitat use that limit mesopredator distribution and abundance. Changes in the abundance of apex predators may have disproportionate (up to fourfold) effects on mesopredator abundance. Outcomes of interactions between predators may however vary with resource availability, habitat complexity and the complexity of predator communities. There is potential for the restoration of apex predators to have benefits for biodiversity conservation through moderation of the impacts of mesopredators on their prey, but this requires a whole-ecosystem view to avoid unforeseen negative effects.ÔNothing has changed since I began. My eye has permitted no change. I am going to keep things like this.Õ From ÔHawk RoostingÕ, by Ted Hughes.

Can we save large carnivores without losing large carnivore science?

“…When the individual empirical studies that form the content of these reviews are judged against Platt's (1964) criteria for strong inference, Hone's (2007) deconstruction of experimental design capabilities, or Sutherland et al' (2013) 20 tips for interpreting scientific claims, it is clear that even literature reviews (e.g. Ritchie and Johnson, 2009;Estes et al, 2011;Ripple et al, 2014b) seldom offer reliable guidance on the state of the literature addressing the MRH, TCH and BMTCH. These remain intriguing hypotheses, but they are each inadequately tested and not yet demonstrated for almost all large carnivores and contexts.…”

Biodiversity and ecosystem functioning in dynamic landscapes

“…In addition, most BEF experiments have manipulated plants or other low trophic levels [4]; whereas at global scales, species at higher trophic levels show the strongest reduction in population size and the highest risk for extinction [25][26][27][28]. Invasions, at the same time, occur predominantly at intermediate trophic levels [29], which also profit from the decline of top predators (a phenomenon called mesopredator release [30]). Thus, there is a clear mandate to analyse the functional consequences of biodiversity change in a multi-trophic food web context [28,31,32].…”

Focusing Ecological Research for Conservation

“…Restoration of top predators can benefit biodiversity by alleviating the effects of mesopredators on prey (Ritchie and Johnson 2009), but recent evidence suggests that once predators have been removed, ecosystems can require a long time to recover even when predator reintroductions are successful (Marshall et al 2013). However, ecosystem recovery rates must be assessed in other systems in order to allow generalization.…”