Hypotheses Of The Effects Of Wolf Predation

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Hypotheses of the Effects of Wolf Predation

Abstract: This paper discusses four hypotheses to explain the effects of wolf

predation on prey populations of large ungulates. The four proposed hypotheses

examined are the predation limiting hypothesis, the predation regulating

hypothesis, the predator pit hypothesis, and the stable limit cycle hypothesis.

There is much research literature that discusses how these hypotheses can be

used to interpret various data sets obtained from field studies. It was

concluded that the predation limiting hypothesis fit most study cases, but that

more research is necessary to account for multiple predator - multiple prey


The effects of predation can have an enormous impact on the ecological

organization and structure of communities. The processes of predation affect

virtually every species to some degree or another. Predation can be defined as

when members of one species eat (and/or kill) those of another species. The

specific type of predation between wolves and large ungulates involves

carnivores preying on herbivores. Predation can have many possible effects on

the interrelations of populations. To draw any correlations between the effects

of these predator-prey interactions requires studies of a long duration, and

statistical analysis of large data sets representative of the populations as a

whole. Predation could limit the prey distribution and decrease abundance. Such

limitation may be desirable in the case of pest species, or undesirable to some

individuals as with game animals or endangered species. Predation may also act

as a major selective force. The effects of predator prey coevolution can explain

many evolutionary adaptations in both predator and prey species.

The effects of wolf predation on species of large ungulates have proven to be

controversial and elusive. There have been many different models proposed to

describe the processes operating on populations influenced by wolf predation.

Some of the proposed mechanisms include the predation limiting hypothesis, the

predation regulating hypothesis, the predator pit hypothesis, and the stable

limit cycle hypothesis (Boutin 1992). The purpose of this paper is to assess the

empirical data on population dynamics and attempt to determine if one of the

four hypotheses is a better model of the effects of wolf predation on ungulate

population densities.

The predation limiting hypothesis proposes that predation is the primary factor

that limits prey density. In this non- equilibrium model recurrent fluctuations

occur in the prey population. This implies that the prey population does not

return to some particular equilibrium after deviation. The predation limiting

hypothesis involves a density independent mechanism. The mechanism might apply

to one prey - one predator systems (Boutin 1992). This hypothesis predicts that

losses of prey due to predation will be large enough to halt prey population
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