Predation and Predator management

PREDATIONAND PREDATORMANAGEMENT

ABSTRACTPredation and can be seen as a simple phenomenon of one animal killing and eating the other. But it is not the case since predationis very comprehensive due to processes involved, animal behavior, survival for the fittest, ecological balance and soon. Much will be explained in thisthesis.

Gwakisa KalingaPrinciples of Wildlife Parks and sites, Ecology Management.

Introduction

Definition of Predation

Predation can be generally defined as any interaction between two

organisms that result in a flow of energy between them. The

interaction can be positive or negative and includes both

predator-prey, herbivore-plant, and parasite-host interactions.

The process involved is, an organism have to spend some effort to

locate a live prey, plant or a host and in addition spend another

effort to mutilate or kill it and enhancing its survival. Many

people tend to generalize predation to carnivorous only but

predation is applicable to both animals and plants. It should be

noted that the whole food chain is the cycle of predation that is

from the source of life for all life which is the sun, Plants

utilize the sun’s energy, animals eat plants and utilize the

plants’ energy, and some animals eat other animals and utilize

their energy.

Mathematical models and logic suggests that a coupled system of

predator and prey should cycle that is predators increase when

1 | P a g e University of Dar es salaam Business School

Bachelor of commerce in Tourism and hospitality mangt. Author: Gwakisa Kalinga

Year of study: 2011-2014

prey are abundant, prey are driven to low numbers by predation,

the predators decline, and the prey recover, ad infinitum.

A sample of a common predator- Prey cycle

Source:http://en.wikibooks.org/wiki/Ecology/Predat

ion_and_Herbivory#ref_sih1985 (Cited on April 20, 2013)

This cycle forms a major driving force in evolution, as predator

density increases, the number of prey consumed also increases.

Thus preys adapt to avoid consumption by predators and live on

and reproduce and they pass their survival skills to their young.

The predator also adapt to become more efficient and the

individual which cannot capture any prey die off and better2 | P a g e University of Dar es salaam Business School



http://en.wikibooks.org/wiki/Ecology/Predation_and_Herbivory#ref_sih1985

http://en.wikibooks.org/wiki/Ecology/Predation_and_Herbivory#ref_sih1985

adapted population lives on. This continues as an evolutionary

predator-prey cycle.

Examples

Predators are animals like Lion, Cheetah, Hyena, Wild Dog, Tiger,

Panther and others also can be plants like carnivorous plants

such as Bladderwort, Sundew, Venus-fly trap and others. Preys can

be animals such as Zebras, Wild beast, Antelope, Gazelle, Rabbit

and others also.Preys can be plants such as Grasses, Plant

leaves, Tree barks and others.

Forms or Types of Predation

There are four major forms of predation which are Carnivory,

Herbivory, Parasitism and Mutualism. Each type of predation can

be categorized based on whether or not it results in the death of

the prey. Carnivory is lethal to the prey while herbivory and

parasitism may or may not be lethal to the prey. Mutualism is not

lethal to either predator or prey but, rather, benefits both

organisms.




http://en.wikipedia.org/wiki/en:Mutualism

http://en.wikipedia.org/wiki/en:Parasitism

http://en.wikipedia.org/wiki/en:Herbivory

Carnivory, this is the case to organisms which prefer meat over

plants, takes place when a predator consumes meat, rather than

plants and consequently kills its prey. Some types of carnivores

do not need to eat meat in order to survive, but do so any way.

Further categorization is made to Obligatory carnivores (cannot

survive without meat in their diet though they can eat plants

sometimes) and Hypercarnivores (are able to eat only meat duet to

restricted digestive capabilities).

Carnivorous habits can also occur in plants and fungi that feed

on insects or microscopic invertebrates. Such as Bladderwort and

Sundew.

Herbivory is a type of predation in which animals/organisms

consume autotrophs such as plants, algae, and photosynthesizing

bacteria. Herbivory is a term commonly used to describe the

consuming of plants by animals. Subcategories are Monophagous and

Polyphagous. Monophagous eat one plant species and their survival

depend on the survival of their promari source of food.

Monophagous are also immune to plant’s defenses both mechanical

and chemical. For example Monarch Butterfly that feeds on

milkweed is immune to its toxic defenses.4 | P a g e University of Dar es salaam Business School



Polyphagous feed on more than one type of plant species, most

herbivores are in this kind

Sub groups in Polyphagous are Frugivors (eat primarily fruits),

Folivors (eat leaves), Nectarivores (eat nectar) .The highest

rate of herbivory occur in rainforests.

Parasitism occurs when one organism (a parasite) benefits at the

expense of another (host). This type of interaction harms the

host but it’s not like in carnivory, doesn’t always result in

death of the host but the host can suffer infection sometimes.

Normally the parasite is much smaller than the host and has a

much faster reproductive rate. Example is the tapeworm in human

digestive system.

Mutualism is similar to parasitism except that the host is not

harmed. That is both species benefit from the interaction.

Example of this type of predation the endosymbiotic theory

stating that at some point in the past an anaerobic cell engulfed

a bacterium and a mutualist relationship resulted.




Therefore the whole process of predations is a form of

competition for survival. A predator tend to develop distinct

adaptive feature which will help to capture a prey while preys

too will develop distinct features for their own defense against

predators as explain in the following title.

The distinctive features of predators

Predatory behaviour is that which results in in to the killing of

another animals or prey for food. Some predators such as lions

and tigers are large and ferocious, while others can be small in

appearance such as lady bugs but however lady bugs can be seen

ferocious to their prey which is tiny insect sometimes called

aphids. There also some predators such as bears and crows eat a

mixed of diet that includes a lot of plant materials as well as

other animals. Other animals such as frog, lizards and most

species of wild cats are more strictly carnivorous and their diet

consists almost entirely of animals.

Predators usually possess senses to find their prey and special

abilities to capture those prey, for example predatory birds they




possess outstanding eye sight and often hearing as in the case of

owls, for example the peregrine falcon is a magnificent bird

hawk, it flies high up to the sky and in the air peregrine has

exceedingly keen vision when a potential prey is sighted flying

along below the peregrine closes its wings and dives or stoops to

make its ambush most effective. And it is estimated that the

peregrine falcon reaches a speed of 300km/hr almost 100m/sec.

most preys are killed instantly by the sudden jolt of the

peregrine falcon.

Other predators such as many species of mammals have very keen

sense of smell which helps them locate preys, also many predators

are fast and they use their speed so as to capture prey for

example cheetahs predators of the African savannah are the

world’s fastest runners also falcon, predators of other bird

species are the world’s fastest fliers and barracudas are very

fastest swimmers.

Predator-Prey interaction and impact on their populations




Predation can have direct effects on the population dynamics of

both the predator and prey populations. For example, an increase

in predator density increases the chances that a prey individual

will be captured and thus, decreases the survival rate of the

prey population. Lower prey survival leads to lower prey

abundance and this can decrease the survival rate of the predator

population. With few predators in the area, the prey population

recovers and the process repeats itself. This is called a

population cycle.

Predators may also have indirect effects on their prey. Prey

species often change their behavior and adopt defensive tactics

in the presence of a predator. For example, a prey individual may

be less likely to risk feeding in areas that are not protected by

cover even if those unprotected areas are rich in food. The

predator is therefore having a negative effect on the prey

without ever interacting with it. Other defensive tactics include

the schooling or herding behavior of prey animals and the

production of distasteful chemicals by plants to ward off

herbivores. Both tactics have costs associated with them and




thus, the predators are asserting indirect effects on their prey.

These defensive tactics, in turn, can indirectly effect predators

to evolve better capture techniques or resistance to plant

chemicals.

Adaptation of prey and predators in the ecosystem

Adaptation is a body party, body covering, or behavior that

enables an organism to survive in the environment. Adaptation can

be in terms of behavioral or physical characteristics which fall

into three main groups that is body parts, body covering and

behaviors. Adaptation under the predator-prey relationship

develop in which for the case of prey organisms aim at protecting

themselves against predators while for predators aims at

developing efficiency of obtaining their prey as a source of food

for their survival.

Prey animals are often well adapted in relation to the commonest

predators which excel in acuteness of senses, learn by experience

and highly selective among potential victims. Its natural

selection that favors prey to adopt and avoid being found, caught




and eaten while increases predator’s ability or efficiency of

finding, capturing and eating its prey. Those two selective

processes oppose each other because as the prey become more

adopting at escaping from predators the predators in turn evolve

efficient mechanism for capturing them.

Hence in the evolution of predator –prey relationship the

predator evolves so as dissociate itself from the interaction

while the predator continually maintains the relationship. Prey

have equally developed escape mechanism such as posting of

sentinels, predator alarm, background color matching and thorns

which help prey organisms to escape before they come close with

their predators, that is why most predators hunt by ambush.

Example in terms of body parts (physical adaptation) predators

and prey organisms have evolved wings, sharp claws, sharp teeth

and webbed feet in which for prey organism is for defense against

predators while for predators is for obtaining their prey. Wings

help the predators like black eagle or vampire bat to fly faster

and catch their prey, while the same wings are used by smaller

birds to run away from these predators.




Webbed feet help predators to swim faster and catch their prey

organism while prey organism can use them to run from the

predators, sharp claws help predators like lion to kill easily

their prey as well as for tearing meat while prey use them to

warn their predators to back off like what happens with bears

that uses claws for defense, sharp teeth like for leopards help

them to kill, chew and tear their prey while gorillas can use

them to show power or fear to the leopard, that’s why predators

should have more resources at their disposal and should normally

be more fit than their prey and that is the reason why in many

occasions predators choose the easiest prey available like young,

sick, victims of accident, aging.

Also prey organism use camouflage and mimicry in which for the

case of camouflage animals blend in with its surrounding, its

shape, color and patterns of its coat which enables to look like

the environment and sometimes look like a tree bark or dead

leaves, this can be evidenced for the case of chameleon for the

purpose of defense, but the same can be used by predators so that

they cannot be seen by their prey and catch them easily. Mimicry




refers to the situation where by animal look similar to another

animal that is dangerous to the predators in which the dangerous

animal may have toxins making undesirable for the predators,

animals that copy appearance are called mimics and those having

toxins are called models.

Ecological role of predators

The health of natural systems relies on the presence of

predators, where by the intact healthy ecosystem provides

benefits or they are important to humans simply because they

provide clean water, forest regeneration, seed dispersal as well

as natural pest control, climate regulation, healthy native plant

communities in uplands which in turn they contribute to soil

fertility, stream bank stability, healthy fish and insect

population.

When predators are removed from their food webs, the system

becomes unbalanced and unhealthy, we simply cannot keep the

current pace of species and habitat reduction or elimination if

we want to maintain the ecological balance of nature. In fact the




predators are the keystone meaning that their presence or absence

has significant impact on the surrounding biological community.

Predator species greatly impact their environment simply because

they survive by preying on other organisms whereby they send

ripples throughout the food web, regulating the effects of other

animals have on that ecosystem. This cause and effect process is

called trophic cascade or the progression of direct {predation

driven} and indirect {fear driven} effects that predators have

across lower nutritional {trophic} levels in food chain.

Predators also have sideways and circular impacts throughout

their communities because they affect the behaviour of competitor

predators, or animals that eat the same prey they do. In some

cases, dominant predators even kill and eat their competitors

(termedintraguild predation). These effects in turn impact the

animals in the competitor’s food chain, which on the whole is an

overlapping yet different set of animals than in the dominant

predator’s food chain. One of the most frequently studied

dynamics between predators involves wolves and coyotes. Wolves

regulate the numbers, movement, and distribution of coyote




populations because wolves are dominant. When coyote populations

are held in check, animals lower down in the coyote’s food chain

tend to have higher survival rates, as has been found with

pronghorn and sage grouse. Thus, top predators support prey

species at lower levels, again in turn triggering a whole host of

other effects that contribute to the healthy functioning of a

natural area.

In addition to regulating natural systems as described above,

predators (especially large predators) serve as a measure of the

health of communities around them. Top predators are associated

with high biodiversity value because, they are sensitive to

ecosystem dysfunctions, such as pollution, habitat fragmentation,

and other human impacts that would affect many species. Also they

select sites with productive habitat and vegetation complexity

and lastly most have diets dominated by a few main prey species

but a large number of secondary prey species. Communities with

many prey species are richer and allow for prey-switching if

necessary, which helps prey populations persist yet still allows

for top-down regulation of the area by the predator.




Conclusively, Top predators typically need large areas for

foraging and breeding and are thus considered umbrella species

that is, if an area supports a large predator, it will encompass

the requirements of less demanding species. Finally, because of

their large area requirements, many predator species serve as a

draw for tourists, encouraging the protection of wild spaces

while generating income and employment.

Predators Management

Predators management refers to the process of balancing predation

of organisms in the animal populations. The predation management

is of significant importance if you take into account the threats

of unbalanced relationship to the surrounding social communities

near by the parks, game reserve or conservation area particularly

farmers, livestock owners and other villagers.

Most of the government authorities tend to manage predators

particularly large predators like lions, leopards, hyenas,




cheetahs, crocodiles and etc., below their biological carrying

capacity because it’s better for predators to be minimal than

preys instead of predators to be maximum than preys. Potential

threats to predators includes loss of habitat and land use

change, retaliatory killing and unregulated tourism may pose

important threat to predator conservation management.

Control alternatives for managing predation on wildlife

It’s important to develop a control strategy that will address

the followings;

Species to be controlled

The scale of control

The season and length of control

Lethal and non-lethal methods to be used

The cost benefit ratio

There are two control alternatives for managing predation in

wildlife;.16 | P a g e University of Dar es salaam Business School



Lethal methods

Non-lethal methods

Under lethal methods includes; Foothold traps (wide range of

applications), Neck snares (easily used but not selective),

Calling/Shooting (highly selective but time consuming), Aerial

gunning (highly effective for some species and situations but can

be expensive).

Foothold traps; Is versatile and available in sizes and shapes

appropriate for coyotes, lions, wild dogs, etc. The size or

number of the traps should correspond with the size of the

predator. Stakes or drags must be attached to the trap to anchor

the trapped predator. When doing traps the trapper should wear

the gloves when handling clean traps and when setting traps

because many predators (especially canines) have a keen sense of

smell and can detect human’s odors on buried traps. Pick trap

sites wisely to avoid catching non target animals. Good places

where predators travel regularly including roads and trail

intersections, water holes, fence corners, ‘crawls’ under




fences, pasture gates, stream crossing and fresh animal

carcasses.

Snares; Are rather simple mechanical devices. They are

economical, effective and do not require as much skills or

training to use correctly. Any animal travelling through a snare

is likely to be caught so they must be used with extreme care.

When tripped the snare start to close around the head or body and

the locking device keep the loop tight. Snares are used where

there’s net wire fencing. They are setting under the fence or

between wires where animals pass through.

Shooting; It is the most lethal control method because the

predator is seen before it is taken. Shooting can be done with or

without calling. Most predatory species can be calling within a

short distance concealed hunter. Calling is done with a mouth

blown call or with an electronic device that imitates the sound

of the animal. A caller must blend with the background. Decoys

and scents can be useful in attracting predator’s attention away

from the caller. Remember predators may show up from any




direction and disappear as quickly as possible. Predators can

become call shy which means they will not respond to the calling.

Probable causes are too much calling in the area, improper

calling, missed shots, or carelessness on the part of the caller

or hunter.

Aerial gunning; Is the use of the aircraft (fixed wing or

helicopters) to take target animals that are causing problems or

to quickly reduce the number of predators. Aerial gunning is most

effective in area with open, flat terrain and little brush. A

fixed wing air craft is most often used over flat or gently

rolling terrain with little brush cover, where as a helicopter

can be used for all types of terrain and cover. A12 semiautomatic

short gun is the weapon of choice for aerial hunting from either

types of aircraft.

In non-lethal methods include; Habitat enhancement (usually first

line of defense, examples are improving nest cover), Fencing

(most effective for free ranging animals), Cage traps ‘live




traps’ (effective for many species but not coyotes), Conditioned

Taste Aversion, Immuno-contraception (experimental).

Habitat enhancement is the most natural way to minimize

predation. This involves manipulating the habitat to favor prey

species. Generally the more cover available to the prey species

the letter its odds of survival. Habitat enhancement ranges from

strategic brush removal to subtle changes in grazing.

Fencing; This can restrict or funnel predator movement. This

method cannot be applied in national parks or large game reserve

but can be applicable in zoo. Sometimes can involves the use of

modifying net wire fences with electrified trip wire and buried

aprons and make them a greater different to predators and keep

them from avoid to crossing fence lines. Maintaining such

electrical fencing sometimes require sometimes considerable time

and effort, especially if vegetation is dense.

Conditioned taste aversion; Is the process by which animals come

to associate the taste of a food with an acute gastric illness

that occurs soon after consumption. It is largely experimental




and it’s not likely to become a tool for controlling predation on

game animals, but it may someday useful in controlling nest

predation, especially when predators are small and also when

occupy small overlapping ranges.

Cage traps; are in expensive available in many sizes, easy to use

and can be used almost anywhere. They are also called live traps

because trapped animals are not harmed and non-target animals can

be released. Cage traps is not usually used to catch coyotes. The

size of the trap and the bait used should corresponding to the

size of the target. Baits include corns, pet food, meat, fish and

eggs. Large cage traps that can hold several animals are also

good in catching wild animals but there are hazards when wild

animals are trapped you must be cautious when releasing it.




References

1. L.J Milne, The Arena of Life, 1972

2. L. Martin and Diamond M., Ecology and Evolution of

communities, 1975 The Belknap Press of Harvard university

press.

3. http://en.wikibooks.org/wiki/Ecology/

Predation_and_Herbivory#endnote_Preston2009 (cited on April

19, 2013)

4. Michael Grahm, Natural Ecology, 1973




http://en.wikibooks.org/wiki/Ecology/Predation_and_Herbivory#endnote_Preston2009

http://en.wikibooks.org/wiki/Ecology/Predation_and_Herbivory#endnote_Preston2009

5. Pianka R. Eric, Evolutionary Ecology 1978, Harper and Row

publishers.

6. http://www.globalchange.umich.edu/globalchange1/current/

lectures/predation/predation.html ( April 20/2013)

7. Bolen, Eric G. and Robinson, William L. Wildlife ecology

and management, 5th edition 2003.




Predation and Predator management

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