Do short-term behavioural responses of consumers in tri-trophic food chains persist at the population time-scale?

We present a theoretical study of individual response to the feeding efficiency-predation risk trade-off in tri-trophic food chains where consumers (the species at the intermediate trophic level) choose their activity level to maximize their fitness. We derive the optimal level of foraging activity as a function of resource abundance and predation risk, and we study the long-term effects of these behavioural traits on population dynamics. We compare different models of population dynamics and we show that long-term predictions depend heavily on the model description. In particular, linear functional responses lead to maximal foraging activity of consumers at the population equilibrium, while Holling type II functional responses can lead to moderate or low levels of consumer activity at the population equilibrium.