Our model predators were custom-made, to match photographs of the real predators, and positioned in their natural resting or hiding position [30] (see fig. 3).
If no real predator was encountered during this 2-hour period, a predator model was positioned so that the subjects could not observe the procedure.
Azar et al. [19] studied the Lotka Volterra type two prey one predator model where the predator is harvested with two different schemes: (i) constant harvesting quota and (ii) constant harvesting effort, and one reported that a constant harvesting quota on the predator may destabilize the system.
While predator-prey models with free boundary have attracted great attention, almost all of the studied models assume that the predator is a specialist, which means that the predator will certainly go to extinction in the absence of the focal prey.
This can occur both in models in which the top predator is a specialist, completely dependent upon the herbivore, and in models in which the top predator is a generalist, inflicting mortality upon the focal prey species, but itself sustained in numbers by alternative prey.
Leslie model is a predator-prey model where the carrying capacity of the predator is proportional to the number of prey, stressing the fact that there are upper limits to the rates of increase in both prey x and predator y, which are not recognized in the Lotka-Volterra model.
Birds of prey, such as the sparrowhawk, were chosen as model predators because they are one of the most common and important predators of great and blue tits [ 33, 35, 55- 59].
However, in many cases, when predators have to search for food and, therefore, have to share or compete for food, the functional response in prey-predator model should be predator-dependent.
Some biologists have argued that in many instances, especially when predators have to hunt for food and, therefore, have to share or compete for food, the functional response in a prey-predator model should be predator-dependent.
In addition, both voles and predators were modeled through an individual-based approach, thus emergent population patterns were the result of intra- and inter specific interactions between individuals, not pre-assumed population characteristics.
