Wolf Predation Essay Research Paper Effects of

Wolf Predation Essay, Research Paper

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

relationships.

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 increase.

Many studies support the hypothesis that predation limits prey

density. Bergerud et al. (1983) concluded from their study of the

interrelations of wolves and moose in the Pukaskwa National Park that

wolf predation limited, and may have caused a decline in, the moose

population, and that if wolves were eliminated, the moose population

would increase until limited by some other regulatory factor, such as

food availability. However, they go on to point out that this upper

limit will not be sustainable, but will eventually lead to resource

depletion and population decline. Seip (1992) found that high wolf

predation on caribou in the Quesnel Lake area resulted in a decline in

the population, while low wolf predation in the Wells Gray Provincial

Park resulted in a slowly increasing population. Wolf predation at the

Quesnel Lake area remained high despite a fifty percent decline in the

caribou population, indicating that mortality due to predation was not

density-dependent within this range of population densities. Dale et

al. (1994), in their study of wolves and caribou in Gates National

Park and Preserve, showed that wolf predation can be an important

limiting factor at low caribou population densities, and may have an

anti-regulatory effect. They also state that wolf predation may affect

the distribution and abundance of caribou populations. Bergerud and

Ballard (1988), in their interpretation of the Nelchina caribou herd

case history, said that during and immediately following a reduction

in the wolf population, calf recruitment increased, which should

result in a future caribou population increase. Gasaway et al. (1983)

also indicated that wolf predation can sufficiently increase the rate

of mortality in a prey population to prevent the population’s

increase. Even

Внимание, отключите Adblock

Вы посетили наш сайт со включенным блокировщиком рекламы!
Ссылка для скачивания станет доступной сразу после отключения Adblock!

Скачать