Invasion of an exotic species initiated by its local introduction is considered subject to predator-prey interactions and the Allee effect when the prey growth becomes negative for small values of the prey density. Mathematically, the system dynamics is described by two nonlinear diffusion-reaction equations in two spatial dimensions. Regimes of invasion are studied by means of extensive numeri...

We consider a general model for predator-prey interactions in which the instantaneous per unit growth rate j i — ft(Nv N2)(t) of each species at any time t is a functional of species densities N^s) at previous times s ^ t. We assume that the equation for prey density Nx obtained from the model in the absence of predators (N2 — 0) possesses at least one positive equilibrium c > 0 (which may or m...

Nonlethal indirect interactions between predators often lead to nonadditive effects of predator number on prey survival and growth. Previous studies have focused on systems with at least two different predator species and one prey species. However, most predators undergo extreme ontological changes in phenotype such that interactions between different-sized cohorts of a predator and its prey co...

Patchy distributions of organisms and environmental conditions are characteristic traits of aquatic environments. Yet biological and physical measurements are often averaged over large spatial scales when used in environmental models. From a fish's perspective, local rather than spatially averaged conditions determine available habitat. We found that a horizontal cell size of 40 m preserved env...

The combined effects of multiple predators often cannot be predicted from their independent effects. Emergent multiple predator effects (MPEs) include risk enhancement, where combined predators kill more prey than predicted by their individual effects, and risk reduction, where fewer prey are killed than predicted. Current methods for detecting MPEs are biased because they assume linear functio...

Geoffrey C. Trussell,* Patrick J. Ewanchuk and Mark D. Bertness Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, U.S.A. *Correspondence and present address: Department of Biology, College of the Holy Cross, 1 College Street, Worcester, MA 01610-2395, U.S.A. E-mail: [email protected] Abstract Studies on the implications of food web interactions to comm...

Diet, prey availability, and breeding success were studied in a population of Bonelli's eagle (Hieraaetus fasciatus) in the province of Granada, SE Spain. The densities of the main prey species, European wild rabbit (Oryctolagus cuniculus), red-legged partridge (Alectoris rufa), wood pigeon (Columba palumbus), and rock dove (Columba livia), representing 90.2% of the biomass, were analysed in 19...

trait effects in community dynamics is to incorporate dynamic state variable models [14] into community models. Also, the traits of predators and prey often depend on the traits of other predators and prey; for example, where and when prey forage is shaped by the distributions and behaviors of other prey and predators [15]. Thus, in these cases, prey behavior is not only a function of the densi...

FROM purely theoretical considerations Lotka (1920) and Volterra (1926) concluded that a biological system consisting of two interdependent species (predator and prey) will exhibit regular periodic fluctuations in respect to the absolute and relative abundance of each species, even when random fluctuations due to external environmental factors have been eliminated. So far as is known this concl...

The probability of prey encounter, attack, capture, and kill are often hypothesized to depend on habitat structure, but field evidence in terrestrial systems is rare. We tested whether predation efficiency by the American marten (Martes americana) and fear of predation by their primary prey, the red-backed vole (Clethrionomys gapperi), differed between 20- to 50-year-old regenerating forest sta...