This is a typical shape of functional response of many predator species. This function indicates the number of prey killed by 1 predator at various prey densities. The graph of functional response that corresponds to this equation is shown below: The last step is to find the number of attacked prey H a: Parameter a is often called "area of discovery", however it can be called "search rate" as well.Īfter spending time T search for searching, a predator examines the area = a T search, and captures aHT search prey where H is prey density per unit area: A predator examines area a per time unit (only search time is considered here) and captures all prey that were found there. Where T h is time spent on handling of 1 prey.Ĭapturing prey is assumed to be a random process. Handling time should be proportional to the number of prey captured: Total time equals to the sum of time spent on searching and time spent on handling::Īssume that a predator captured H a prey during time T. Prey handling which includes: chasing, killing, eating and digesting.Ĭonsumption rate of a predator is limited in this model because even if prey are so abundant that no time is needed for search, a predator still needs to spend time on prey handling.It assumes that a predator spends its time on 2 kinds of activities: This model illustrates the principal of time budget in behavioral ecology. Mathematically, this model is equivalent to the model of enzime kinetics developed in 1913 by Lenor Michaelis and Maude Menten. This model is often called "disc equation" because Holling used paper discs to simulate the area examined by predators. Holling (1959) suggested a model of functional response which remains most popular among ecologists. Holling considered these effects as 2 kinds of responses of predator population to prey density: (1) the functional response and (2) the numerical response. This resulted from 2 effects: (1) each predator increased its consumption rate when exposed to a higher prey density, and (2) predator density increased with increasing prey density. Holling (1959) studied predation of small mammals on pine sawflies, and he found that predation rates increased with increasing prey population density.
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