Predators are animals or organisms that consumes all or part of another living organism, thereby benefiting itself but reducing the growth, fecundity, or survival of the prey.
- In the process of completing development to the adult stage, an immature predator will consume a number of prey.
- Except for the egg, the predator is free living in all life stages
- Usually the eggs are laid in the vicinity of the prey.
- Larvae or predator nymphs actively seek out, capture, kill, and consume prey upon hatching from the egg,
- Many predators are carnivorous in both the immature and adult stages
The relationship between the average number of prey eaten by each predator per unit time vs. prey density
The increase in the number of predators by reproduction and immigration with increases in the prey population
Type I Functional Response
Explanation: Each individual predator takes a fixed fraction of the prey population each time period. If prey density double, the number each predator eats per day doubles Assumptions
Assumptions: Encounter and kill rate is simple fraction of prey population, V No “saturation” or “satiation” of predator No “handling” or “processing” time No “switching” from one prey species to another
Biological Basis: Likely valid for the lower range of prey densities for some species
Type II Functional Response
Explanation: “Saturating functional response” As prey density increases, the number of prey each predator eats per day reaches a constant number.
Assumptions: Encounter rate initially limits predation, but processing/handling time (including digestion) or satiation eventually limits food intake No “switching” from one prey species to another
Biological Basis: Likely applies to most predators, and a nearly Type I response occurs over lower range of prey density.
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