Wolf Predation Essay Research Paper Effects of

Wolf Predation Essay, Research Paper

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Effectss of Wolf Predation

Abstraction: This paper discusses four hypotheses to explicate the effects

of wolf predation on prey populations of big hoofed mammals. The four

proposed hypotheses examined are the predation restricting hypothesis,

the predation modulating hypothesis, the marauder cavity hypothesis, and

the stable bound rhythm hypothesis. There is much research literature

that discusses how these hypotheses can be used to construe assorted

informations sets obtained from field surveies. It was concluded that the

predation restricting hypothesis tantrum most study instances, but that more

research is necessary to account for multiple marauder & # 8211 ; multiple quarry

relationships.

The effects of predation can hold an tremendous impact on the

ecological organisation and construction of communities. The procedures of

predation affect virtually every species to some grade or another.

Depredation can be defined as when members of one species eat ( and/or

putting to death ) those of another species. The specific type of predation between

wolves and big hoofed mammals involves carnivores feeding on herbivores.

Depredation can hold many possible effects on the interrelatednesss of

populations. To pull any correlativities between the effects of these

predator-prey interactions requires surveies of a long continuance, and

statistical analysis of big informations sets representative of the

populations as a whole. Depredation could restrict the quarry distribution

and lessening copiousness. Such restriction may be desirable in the instance

of pest species, or unwanted to some persons as with game

animate beings or endangered species. Depredation may besides move as a major

selective force. The effects of marauder prey coevolution can explicate

many evolutionary versions in both marauder and prey species.

The effects of wolf predation on species of big hoofed mammals have

proven to be controversial and elusive. There have been many different

theoretical accounts proposed to depict the procedures runing on populations

influenced by wolf predation. Some of the proposed mechanisms include

the predation restricting hypothesis, the predation regulation

hypothesis, the marauder cavity hypothesis, and the stable bound rhythm

hypothesis ( Boutin 1992 ) . The intent of this paper is to measure the

empirical informations on population kineticss and effort to find if one

of the four hypotheses is a better theoretical account of the effects of wolf

predation on hoofed population densenesss.

The predation restricting hypothesis proposes that predation is the

primary factor that limits prey denseness. In this non- equilibrium

theoretical account perennial fluctuations occur in the prey population. This

implies that the prey population does non return to some peculiar

equilibrium after divergence. The predation restricting hypothesis

involves a denseness independent mechanism. The mechanism might use to

one quarry & # 8211 ; one marauder systems ( Boutin 1992 ) . This hypothesis

predicts that losingss of quarries due to predation will be big plenty to

arrest prey population addition.

Many surveies support the hypothesis that predation bounds prey

denseness. Bergerud et Al. ( 1983 ) concluded from their survey of the

interrelatednesss of wolves and moose in the Pukaskwa National Park that

wolf predation limited, and may hold caused a diminution in, the elk

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

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

nutrient handiness. However, they go on to indicate out that this upper

bound will non be sustainable, but will finally take to resource

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

predation on reindeer in the Quesnel Lake country resulted in a diminution in

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

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

Quesnel Lake country remained high despite a 50 per centum diminution in the

caribou population, bespeaking that mortality due to predation was non

density-dependent within this scope of population densenesss. Dale et

Al. ( 1994 ) , in their survey of wolves and reindeer in Gates National

Park and Preserve, showed that wolf predation can be an of import

restricting factor at low reindeer population densenesss, and may hold an

anti-regulatory consequence. They besides province that wolf predation may impact

the distribution and copiousness of caribou populations. Bergerud and

Ballard ( 1988 ) , in their reading of the Nelchina reindeer herd

instance history, said that during and instantly following a decrease

in the wolf population, calf enlisting increased, which should

consequence in a future reindeer population addition. Gasaway et Al. ( 1983 )

besides indicated that wolf predation can sufficiently increase the rate

of mortality in a prey population to forestall the population & # 8217 ; s

addition. Even though there has been much support of this hypothesis,

Boutin ( 1992 ) suggests that & # 8220 ; there is small uncertainty that predation is a

restricting factor, but in instances where its magnitude has been measured,

it is no greater than other factors such as hunting. & # 8221 ;

A 2nd hypothesis about the effects of wolf predation is the

predation modulating hypothesis, which proposes that predation

regulates prey densenesss around a low-density equilibrium. This

hypothesis fits an equilibrium theoretical account, and assumes that following

divergence, prey populations return to their preexistent equilibrium

degrees. This marauder modulating hypothesis proposes that predation is

a density-dependent mechanism impacting low to intercede quarry

densenesss, and a density-independent mechanism at high quarry densenesss.

Some research supports predation as a regulation mechanism.

Messier ( 1985 ) , in a survey of elk near Quebec, Canada, draws the

decision that wolf-ungulate systems, if regulated of course,

stabilise at low quarries and low marauder population densenesss. In

Messier & # 8217 ; s ( 1994 ) subsequently analysis, based on 27 surveies where

elk were the dominant prey species of wolves, he determined that

wolf predation can be density-dependent at the lower scope of elk

densenesss. This consequence demonstrates that predation is capable of

modulating hoofed populations. Even so, harmonizing to Boutin ( 1992 )

more surveies are necessary, peculiarly at high elk densenesss, to

determine if predation is regulative.

A 3rd proposal to pattern the effects of wolf predation on quarry

populations is the marauder cavity hypothesis. This hypothesis is a

multiple equilibria theoretical account. It proposes that predation regulates quarries

densenesss around a low-density equilibrium. The prey population can

so get away this ordinance one time prey densenesss pass a certain

threshold. Once this takes topographic point, the population reaches an upper

equilibrium. At this upper equilibrium, the prey population densenesss

are regulated by competition for ( and or handiness of ) nutrient. This

marauder cavity hypothesis assumes that marauder losingss are

density-dependent at low quarry densenesss, but reciprocally

density-dependent at high quarry densenesss. Van Ballenberghe ( 1985 )

provinces that wolf population

ordinance is needed when a reindeer herd

population diminutions and becomes trapped in a marauder cavity, wherein

marauders are able to forestall caribou populations from increasing.

The concluding theoretical account that attempts to depict the effects of

predation on prey populations is the stable bound rhythm hypothesis.

This hypothesis proposes that exposure of quarry to predation

depends on past environmental conditions. Harmonizing to this theory,

persons of a prey population born under unfavourable conditions are

more vulnerable to predation throughout their grownup lives than those

born under favourable conditions. This theoretical account would bring forth clip slowdowns

between the proliferation of the marauder and the quarry populations, in

consequence bring forthing repeating rhythms. Boutin ( 1992 ) states that if this

hypothesis is right, the effects of nutrient handiness ( or the deficiency

of ) should be more elusive than straight-out famishment. Relatively terrible

winters could hold long- term effects by changing growing, production,

and exposure. Thompson and Peterson ( 1988 ) reported that there

are no documented instances of wolf predation enforcing a long-run bound

on hoofed populations independent of environmental influences. They

besides point out that summer moose calf mortality was high whether

marauders were present or non, and that snow conditions during the

winter affected the exposure of calves to predation. Messier

( 1994 ) asserts that snow accretion during back-to-back winters does

non make a cumulative impact on the nutritionary position of cervid and

elk.

All of the four proposed theories mentioned supra could depict

the interrelatednesss between the predation of wolves and their usual

north American quarry of big hoofed species. There has been ample

grounds presented in the primary research literature to back up any

one of the four possible theoretical accounts. The predation restricting hypothesis

seems to bask broad popular support, and seems to most accurately

describe most of the tendencies observed in predator-prey populations.

Most research workers seem to believe that more specific surveies need to be

conducted to happen an ideal theoretical account of the effects of predation. Bergerud

and Ballard ( 1988 ) stated & # 8220 ; A simple Numberss argument sing

quarry: marauder ratios overlooks the complexnesss in multi-predator-prey

systems that can affect excess killing, linear predation between

marauders, sweetening and intervention between marauder species,

switch over between prey species, and a treble fluctuation in nutrient

ingestion rates by wolves. & # 8221 ; Dale et Al. ( 1994 ) stated that farther

cognition of the factors impacting quarry exchanging, such as

density-dependent alterations in exposure within and between quarry

species, and farther cognition of wolf population response is needed

to pull any steadfast decisions. Boutin ( 1992 ) besides proposed that the

full impact of predation has rarely been measured because research workers

have concentrated on mensurating losingss of quarry to wolves merely.

Recently, bear predation on moose calves has been found to be

significant, but there are few surveies which examine this phenomenon

( Boutin 1992 ) . Messier ( 1994 ) besides pointed out that silvertip and black

bears may be of import marauders of moose calves during the summer.

Seip ( 1992 ) , excessively, provinces that bear predation was a important cause

of grownup reindeer mortality. These points emphasize that

multiple-predator and multiple-prey systems are likely at work in

the natural environment, and we must non over generalise a 1

marauder & # 8211 ; one quarry hypothesis in the effort to construe the overall

tendencies of the effects of predation of wolves on big hoofed mammal

populations.

Literature Cited

Bergerud, A. T. , W. Wyett, and B. Snider. 1983. The function of wolf

predation in restricting a moose population. Journal of

Wildlife Management. 47 ( 4 ) : 977-988.

Bergerud, A. T. , and W. B. Ballard. 1988. Wolf predation on reindeer:

the Nelchina herd instance history, a different reading. Journal of

Wildlife Management. 52 ( 2 ) : 344- 357.

Boutin, S.. 1992. Depredation and moose population kineticss: a review.

Journal of Wildlife Management. 56 ( 1 ) : 116-127.

Dale, B. W. , L. G. Adams, and R. T. Bowyer. 1994. Functional response

of wolves feeding on barren-ground reindeer in a multiple quarry

ecosystem. Journal of Animal Ecology. 63: 644- 652.

Gasaway, W. C. , R. O. Stephenson, J. L. Davis, P. E. K. Shepherd, and

O. E. Burris. 1983. Interrelationships of wolves, quarry, and adult male in

interior Alaska. Wildlife Monographs. 84: 1- 50.

Messier, F.. 1985. Social organisation, spacial distribution, and

population denseness of wolves in relation to moose denseness. Canadian

Journal of Zoology. 63: 1068-1077.

Messier, F.. 1994. Ungulate population theoretical accounts with predation: a instance

survey with the North American elk. Ecology. 75 ( 2 ) : 478-488.

Seip, D.. 1992. Factors restricting forest reindeer populations and Ir

interrelatednesss with wolves and moose in southeasterly British

Colombia. Canadian Journal of Zoology. 70: 1494-1503.

Thompson, I. D. , and R. O. Peterson. 1988. Does wolf predation entirely

bound the moose population in Pukaskwa Park? : a remark. Journal of

Wildlife Management. 52 ( 3 ) : 556-559.

Van Ballenberghe, V.. 1985. Wolf predation on reindeer: the Nelchina

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Bibliography