Predator satiation is an antipredator adaptation in which prey occur at high population densities

Population density

Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...

, reducing the probability of an individual organism being eaten.
When predators

Predation

In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

 are flooded with potential prey, they can consume only a certain amount, so by occurring at high densities prey benefit from a safety in numbers

Safety in numbers

Safety in numbers is the hypothesis that, by being part of a large physical group or mass, an individual is proportionally less likely to be the victim of a mishap, accident, attack, or other bad event...

 effect. This strategy has evolved in a diverse range of prey, from trees to insects. Predator satiation can be considered a type of refuge from predators.

As available food increases, a predator has more chances of survival, growth, and reproduction. However, as food supply begins to overwhelm the predator's ability to consume and process it, consumption levels off. This pattern is evident in the functional response

Functional response

A functional response in ecology is the intake rate of a consumer as a function of food density. It is associated with the numerical response, which is the reproduction rate of a consumer as a function of food density. Following C. S...

 of type III. There are also limits to population growth (numerical response

Numerical response

The Numerical response in ecology is the change in predator density as a function of change in prey density. The term numerical response was coined by M. E. Solomon in 1949. It is associated with the functional response, which is the change in predator's rate of prey consumption with change in prey...

), dependent on the generation time of the predator species].

This phenomenon is particularly conspicuous when it takes the form of masting, the production of large numbers of seeds by a population of plants.

Some periodical cicada

Cicada

A cicada is an insect of the order Hemiptera, suborder Auchenorrhyncha , in the superfamily Cicadoidea, with large eyes wide apart on the head and usually transparent, well-veined wings. There are about 2,500 species of cicada around the world, and many of them remain unclassified...

 (Magicicada) species erupt in large numbers from their larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

l stage at intervals in years that are prime numbers, 13 or 17. At high density sites, research finds that the number eaten by birds does not increase with the number of cicada individuals and the risk of predation for each individual decreases.

In contrast to predator satiation, a different pattern is seen in response to mutualistic consumers, which benefit an organism by feeding from it (such as frugivore

Frugivore

A frugivore is a fruit eater. It can be any type of herbivore or omnivore where fruit is a preferred food type. Because approximately 20% of all mammalian herbivores also eat fruit, frugivory is considered to be common among mammals. Since frugivores eat a lot of fruit they are highly dependent...

s, which disperse seeds). For example, a vine's berries may ripen at different times, ensuring frugivores are not swamped with food and so resulting in a larger proportion of its seeds being dispersed.