Getting to Know Overpopulation Picture a small herd of deer grazing in a pasture Of course it is always nice to see wild animals living free in the environment However in many places the deer populations have increased to several times their natural levels In an urban or suburban neighborhood this overpopulation by deer is a real problem

Deer living in the city can be a danger to humans and to themselves

What is overpopulation All living organisms need food water and a safe place to live In any ecosystem the amount of available resources determines the ecosystemrsquos carrying capacity or the number of individuals than can be supported within a given area Overpopulation occurs when the population of a species exceeds the carrying capacity and all of the individuals cannot find the resources they need

What causes overpopulation In all species there is normally a balance between the birth rate which is the number of offspring born and the mortality rate which is the number of deaths that occur This balance keeps the population stable over time Changes in the environment however will upset the balance and change the population If there are extra food and other resources available the number of deaths will decrease and the population will grow

Does overpopulation always result from high numbers of individuals

Some species are naturally very numerous but if their environment can support them they do not suffer from overpopulation For example insects are abundant but they are small and the habitat can normally support such high numbers Large animals however require more food and other resources for each individual It may be possible for an ecosystem to support only a few of these larger individuals before it is overpopulated by that species

It is natural for bees to exist in very high numbers

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What might cause deaths to decrease or births to increase

One primary reason that populations surge is the sudden availability of larger amounts of food Another is the disappearance of a predator T he deer population for example has increased steadily in the eastern United States over the past 100 years because mountain lions and other natural predators are no longer present in the ecosystems in which deer now live Modern agriculture has improved diets

which has contributed to lower mortality rates in humans What are the consequeces of

overpopulation All the organisms living in an ecosystem whether they are in the same species or not compete for resources As population numbers increase food is used up at a greater rate and will eventually run short The population decreases again as the resources are depleted by the high numbers of organisms using them

Increases in the populations of prey also support the growth of predatory populations This means that more of the prey is consumed which also helps bring their numbers back down again Over time the population of the predators will decrease again too as their food supplies return to normal levels

How can overpopulation be prevented Overpopulation is a natural response to changes in the environment It cannot be prevented entirely However sometimes overpopulation occurs because human activities have caused changes that affect entire ecosystems It is important that humans to consider whether their activities will increase food supplies diminish predator populations or cause other imbalances that contribute to overpopulation

In this lesson you will learn more about the causes and effects of overpopulation

Misconception 1 Overpopulation is primarily a problem for humans

Overpopulation is a biological event that can affect any species in any part of the world Human populations often experience overpopulation especially in cities where a great number of individuals must rely on a limited number of resources in a small amount of space Plants animals and other organisms however regularly experience cycles of increased and decreased population numbers

Concept Overpopulation Getting to Know wwwdiscoveryeducationcom

2copy Discovery Education All rights reserved

Discovery Education is a subsidiary of Discovery Communications LLC