Population Control

Different Strategies for Population Growth

Before we go directly into discussing population control, we first need to look at the two main population growth strategies. These are referred to as "K-selected" and "r-selected".

The populations of K-selected species are limited by their carrying capacity. In contrast, r-selected species are limited by environmental factors that affect their population's growth rate, such as temperature and moisture level. In general, K-selected species tend to be large and long-lived, with fewer offspring, while r-selected species are small, short-lived and have numerous offspring. Please see the table below for a comparison between the two types, along with some examples.

Population Control Theory

We often see population control methods being used to keep populations of certain wildlife species at manageable sizes.

These populations often become unmanageable in size due to the removal of a natural limiting factor, such as a natural predator. Several different methods can be used to control wildlife populations.

Methods Used to Control Population

In non-human animals, populations are usually controlled through the aforementioned limiting factors. However, in some cases, humans have modified the environment to such an extent that other methods are needed.

Humans can implement several methods to control the deer population, including the following three.

Hunting / Culling

Deer hunting is a popular past time in many parts of the U.S. Hunting and culling are methods of population control that have been employed for many species worldwide:

• some of which are overpopulated due to the removal of predators,

• some of which are non-native/invasive,

• others not overpopulated but deemed too common for human comfort (e.g., some large predators).

Hunting and culling can effectively mitigate overpopulation, but they fail to address the underlying cause.

In many cases, the underlying cause of overpopulation is removing one or more critical predator species.

All of these predators were eradicated from much of their range by humans. These eradications also had unexpected consequences, such as the expansion in the range of coyotes (Canis latrans) and black bears (Ursus americanus) due to a lack of competition from the larger, more dominant predators that were formerly present.

Reintroduction of Predators

Another effective form of population control involves the reintroduction of these predators.

Wolves have long been persecuted by humans and currently exist in only a fraction of their historical range worldwide. The wolves are a significant predator of elk (Cervus Canadensis), which had become overpopulated in the wolves' absence. Since the reintroduction of wolves, elk populations are now under control. This, in turn, resulted in a cascading effect on the ecosystem. With elk populations no longer decimating willows along river banks, beavers (Castor canadensis) have been able to build more dams and have access to more food. This is a fine example of the vital role apex predators play in ecosystems and how they can be utilised to bring ecosystems back into balance.

Habitat Management

The proper management of wildlife habitat can promote the natural population equilibrium of the wildlife present. The protection and management of habitat can allow predators to return to areas of formerly marginal habitat where they may have been eradicated or significantly reduced, allowing them to regulate the populations of prey species.

Humans can manage wildlife habitat by actively removing invasive animal and plant species, adding native plants and animals, and creating specific habitats that native species may use, such as piles of native brush and vegetation debris. This may include creating shelters for specific native species using native vegetation, such as cavities in trees and perching branches. Lastly, the habitat can be protected from the intrusion of livestock and other non-native species through fencing and better regulation of the human presence within the habitat.

Sterilisation / Neutering

Rendering animals unable to breed is another potentially effective way to control populations. Feral domestic animals, particularly cats and dogs, can breed unsustainably and wreak havoc on natural ecosystems. Feral cats, in particular, are voracious predators, and in areas where feral cats are numerous, wildlife populations suffer immensely. One humane way to curb the population of wild pets is through capturing, neutering, and releasing them.

When controlling the human population, things are much more complex for various reasons. Some methods can mitigate the negative impacts of global human population growth. We will go over these in the next section.

Human Overpopulation

Unlike other animals, humans have been able to extend their carrying capacity through the use of artificial technology. The creation of agriculture, in particular, has allowed human and domestic livestock populations to grow beyond their expected natural maximum sizes.

As you can imagine, this puts massive pressure on the Earth's natural resources and ecosystems. An unsustainably expanding human population has resulted in widespread habitat destruction to make way for agriculture, aquaculture, cattle farming, and housing to sustain such a large population. So what do we do about overpopulation?

Global Population Control

Given the significant negative impact that unsustainable human population growth has had and continues to have on the environment and the human quality of life in many countries, several methods of mitigating human population growth have been proposed.

Increased Access to Contraception and Family Planning Globally

On a global scale, nearly half of all pregnancies are unintended or unplanned. Increasing sexual education, access to contraception (including vasectomy), and family planning opportunities could significantly reduce the number of unwanted pregnancies.

While population growth has slowed in many developed countries, lifestyles have become much less sustainable, resulting in a more significant carbon footprint per person than in developing countries. On the flip side, population growth continues to increase in many developing countries, putting further pressure on already threatened ecosystems and facilitating the spread of disease and increased poverty.

One-child Policy

A more controversial form of human population control is implementing a one-child policy.

While theoretically effective, in practice, one-child policies can be tough to enforce and lead to human rights abuses, imbalanced sex ratios, and general discontent throughout a population. Some scholars claim that the one-child policy effectively curbed the country's population growth in China. In contrast, others argue that the reductions were due to increased education and economic development.

Wealth Redistribution

Another way to potentially curb human population growth is the redistribution of wealth. This is because birth rates tend to be lower in wealthier nations with better education and access to contraceptives.

Impact of Human Population Control on Biodiversity

By far, the most significant current threat to the planet's biodiversity is unsustainable human activity. Major industries are destroying large swaths of natural habitat, exacerbating climate change, and driving species to the brink of extinction. Such industries include:

• Palm oil

• Cattle farming

• Sand mining

• Coal mining

All of these industries exist to fuel the needs of an unsustainable human population. In addition, housing developments and farmland continue to encroach more and more into previously undisturbed ecosystems, resulting in further loss of biodiversity and increased human-wildlife conflict. If the human population curbs its growth and becomes more sustainable, biodiversity would likely rebound significantly.

Human Population Control's Effect on Climate Change

Specific industries have had a disproportionate effect on anthropogenic climate change. These industries include:

• Coal mining

• The automobile industry

• Oil drilling

• Cattle farming

These are all significant culprits of increased greenhouse gas emissions, and all of these industries exist to sustain an unsustainable population. A smaller, more sustainable human population combined with more sustainable fuels and technologies would render most of these problems inconsequential.