The influence of the trade-off between consumer-foraging and predation risk on tritrophic food chain dynamics

• We analyze the consequences of a trait characteristic related to consumer foraging behavior on two tri-trophic food chain models.
• Trait and density effects seem to act synergistically, promoting stability.
• The analysis is amenable to other dynamical multispecies models under trait and density mediated interactions.

Ecological interactions may be mediated by density, trait characteristics or both. In trophic interactions, density mediated indirect effects are related to consumption among trophic levels, whereas trait mediated indirect effects are known to interfere substantially in the foraging process by changing behavior, physiology and/or morphology of the species involved, thereby affecting the species’ overall consumption rate. Empirical works report the existence of trait mediated indirect effects in natural systems and their marked influence on food web dynamics. The present study shows that trait and density effects can significantly alter transient phase, long-term dynamics, species coexistence and stability of two specific multispecies chains: (i) a tritrophic food chain; (ii) a tritrophic food chain with allochthonous input to the consumer level. This may point to the important role of density and trait mediated interactions in food web theory.