A recent review of published studies revealed that predators generally have lower population densities than non-predators in a variety of communities. We report here similar results for a highly replicated study of macroinvertebrates that colonized very uniform detrital microcosms in an old field. This pattern persisted even though predators usually were smaller than non-predators, as determine...

Invasive species threaten biodiversity globally, and invasive mammalian predators are particularly damaging, having contributed to considerable species decline and extinction. We provide a global metaanalysis of these impacts and reveal their full extent. Invasive predators are implicated in 87 bird, 45 mammal, and 10 reptile species extinctions-58% of these groups' contemporary extinctions wor...

That predators attack and prey defend is an oversimplified view. When size changes during development, large prey may be invulnerable to predators, and small juvenile predators vulnerable to attack by prey. This in turn may trigger a defensive response in adult predators to protect their offspring. Indeed, when sizes overlap, one may wonder "who is the predator and who is the prey"! Experiments...

Calls of avian predators potentially predict danger for murine rodents. Indeed, exposure of field-experienced rodents to owl calls induces defensive behavior suggesting that recognition of vocalizations of avian predators is innate. To address this hypothesis, we investigated whether laboratory-reared and predator-naive rodents (mice, gerbils, rats) express defensive behavior in response to cal...

Behavioral ecology and population ecology are two separate branches of ecology; studies linking the effect of individual behavior and population dynamics are rare. This paper connects a stochastic optimal foraging model of insect predators with an age structured population model of its prey. I modeled syrphid larvae feeding on cereal aphids, an interaction critical to cereal crops in Germany. T...

Although biologists routinely label animals as predators and prey, the ecological role of individuals is often far from clear. There are many examples of role reversals in predators and prey, where adult prey attack vulnerable young predators. This implies that juvenile prey that escape from predation and become adult can kill juvenile predators. We show that such an exposure of juvenile prey t...

Coevolution may be defined as an evolutionary change in a trait of one species in response to a change in a trait of a second species, followed by an evolutionary response by the second species to the changes in the first. Yet, more complex evolutionary relationships are known to occur, such as Batesian mimicry, where three or more separate species interact along their evolutionary history. Do ...

The abundance of predators and their impact on ecosystem dynamics is a vividly discussed topic in current ecology. In my studies, incorporating field observations, field experiments and theoretical modeling, I explored the importance of predators and predation in a low arctic tundra ecosystem in northern Norway. This involved observing the abundance and spatial activity of predators (raptors an...