Population Control
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Population control is the practice of artificially maintaining the size of any
population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...
. It simply refers to the act of limiting the size of an animal population so that it remains manageable, as opposed to the act of protecting a
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
from excessive rates of
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
, which is referred to as
conservation biology Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an int ...
. While many abiotic and biotic factors influence population control, humans are notably influential against animal populations. Whether humans need to hunt animals for nourishment or simply neuter their pets to prevent reproduction from occurring, these activities actively manage populations. Specifically, population control plays an important role in wildlife populations. Based on the species being dealt with, there are numerous ways populations of the wild are controlled.
Wildlife contraception Wildlife contraceptives are contraceptives used to regulate the fertility of wild animals. They are used to control population growth of certain wild animals. Usage White-tailed deer may be controlled with contraceptives in suburban areas, whe ...
is the act of preventing reproduction in the wild, which subsequently decreases populations. An example of this includes the maintenance of deer populations with the use of vaccines. Other methods to maintain populations include lethal trapping, live trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization. Lethal trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization are methods used to eliminate animal populations and prevent reproduction, whereas live trapping captures species to remove them from a specific area.


Factors influencing population control

Population control can be influenced by a variety of factors. Humans can greatly influence the size of animal populations they directly interact with. It is, for example, relatively common (and sometimes even a legal requirement) to spay or neuter dogs. Spaying – removing the ovaries and uterus of a female animal – medical term =
ovariohysterectomy Neutering, from the Latin ''neuter'' ('of neither sex'), is the removal of an animal's reproductive organ, either all of it or a considerably large part. The male-specific term is castration, while spaying is usually reserved for female animals. ...
. Neutering - removing the testes of a male animal – medical term =
orchiectomy Orchiectomy (also named orchidectomy, and sometimes shortened as orchi or orchie) is a surgical procedure in which one or both testicles are removed. The surgery is performed as treatment for testicular cancer, as part of surgery for transgend ...
. Various humans activities (e.g. hunting, farming, fishing, industrialization, and urbanization) all impact various animal populations. Population control may involve
culling In biology, culling is the process of segregating organisms from a group according to desired or undesired characteristics. In animal breeding, it is the process of removing or segregating animals from a breeding stock based on a specific tr ...
, translocation, or manipulation of the reproductive capability. The growth of a population may be limited by environmental factors such as food supply or
predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...
. The main biotic factors that affect population growth include: *Food – both the quantity and the quality of food are important. The population growth and decline of species depends on the amount of their food availability. The more available food, the more the population grows to meet it. The less nutritious food, the less fertile a species of reproductive age becomes. Snails, for example, cannot reproduce successfully in an environment low in calcium, no matter how much food there is because they need this mineral for shell growth. *Predators – as a prey population becomes larger, it becomes easier for predators to find prey. If the number of predators suddenly falls, the prey species might increase in number extremely quickly. *Competitors – other organisms may require the same resources from the environment, and so reduce the growth of a population. For instance, all plants compete for light. Competition for territory and for mates can drastically reduce the growth of individual organisms. *Parasites – These may cause disease, and slow down the growth and reproductive rate of organisms within a population. Important
abiotic In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them under ...
factors affecting population growth include: *Temperature – Higher temperatures speed up enzyme-catalyzed reactions and increase growth. *Oxygen availability – affects the rate of energy production by
respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...
. *Light availability – for
photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
. light may also control breeding cycles in animals and plants. *Toxins and pollutants – tissue growth can be reduced by the presence of, for example, sulphur dioxide, and reproductive success may be affected by
pollutants A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like o ...
such as
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
like substances. Direct human impacts are not the only ways humans can control animal populations. Often times, humans are indirectly controlling animal populations, in other words, the humans are not aware that their actions are controlling animal populations. For example, new infrastructure and roads can lead to animals being displaced from their natural habitat. Their new habitats that they are forced to move to may not provide the same necessities to them that they require for survival. This will result in a decreasing population as a result of human actions.


Methods for active population control

Animal euthanasia Animal euthanasia ( euthanasia from el, εὐθανασία; "good death") is the act of killing an animal or allowing it to die by withholding extreme medical measures. Reasons for euthanasia include incurable (and especially painful) conditi ...
is often used as a final resort to controlling animal populations. In
Tangipahoa Parish, Louisiana Tangipahoa Parish (; French: ''Paroisse de Tangipahoa'') is a parish located in the southeast corner of the U.S. state of Louisiana. As of the 2010 census, the population was 121,097. The parish seat is Amite City, while the largest city is ...
, the parish performed mass euthanasia on the entire
animal shelter An animal shelter or pound is a place where stray, lost, abandoned or surrendered animals – mostly dogs and cats – are housed. The word "pound" has its origins in the animal pounds of agricultural communities, where stray livestock would ...
population, including 54 cats and 118 dogs that were put to death due to a widespread disease outbreak that spread among the animals.
Neutering Neutering, from the Latin ''neuter'' ('of neither sex'), is the removal of an animal's reproductive organ, either all of it or a considerably large part. The male-specific term is castration, while spaying is usually reserved for female animals. ...
is another option available to control animal populations. The annual
Spay Day USA World Spay Day advocates spaying, or neutering, advocating it "as a proven means of saving the lives of companion animals, community (feral and stray) cats, and street dogs who might otherwise be put down in a shelter or killed on the street." It is ...
event was established by the
Doris Day Animal League The Doris Day Animal League was an animal advocacy group based in Washington, D.C. It established the annual observance Spay Day USA in 1994, which the group uses to bring attention to the pet overpopulation problem in the United States. On Sep ...
to promote the neutering of pets, especially those in
animal shelter An animal shelter or pound is a place where stray, lost, abandoned or surrendered animals – mostly dogs and cats – are housed. The word "pound" has its origins in the animal pounds of agricultural communities, where stray livestock would ...
s, so that the population remains controllable.


Wildlife population control

Wildlife contraception Wildlife contraceptives are contraceptives used to regulate the fertility of wild animals. They are used to control population growth of certain wild animals. Usage White-tailed deer may be controlled with contraceptives in suburban areas, whe ...
is used to regulate populations of animals in the wild and halt reproduction. For example, vaccines are currently being used in deer populations. GonaCon, which was developed by the US Department of Agriculture, encourages the production of antibodies in the sex drive hormones. Specifically, it is said to remove the oestrous cycles from the females, which initially attracts the males; without the oestrous cycles, males are not interested in mating. Another type of vaccine that is being used in deer is called porcine zona pellucida (PZP). PZP works by blocking sperm with antibodies on the deer's egg surface. When preventing reproduction fails to control populations, methods such as lethal trapping, live trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization are used to maintain populations. Lethal trapping is a method used to kill animals. This type of method is usually monitored in order to ensure no ethical or public concerns arise. While this tactic is most commonly used on small animals, populations of larger animals such as beavers and foxes are also controlled with this type of method. Live trapping is a method used to capture a variety of animals. From small animals to large animals, this type of population control method uses barrel traps, restraining snares, and leg-hold devices. Just like the lethal trapping method, this tactic also needs to be regularly monitored to ensure no ethical concerns arise, as well as reduce animal distress. Specifically, this type of population control method is popular with capturing birds. Egg/roost site manipulation is used on birds to prevent them from nesting in prohibited areas. Water spray is popular in urban and agricultural areas as it uses sprinklers to omit surfactants. The surfactants then control bird populations by killing and preventing future birds from nesting. Live-ammunition shooting uses firearms to eliminate animals such as birds and bears. Because this type of population control method is restricted in many parts of the world, it is only to be used when other control methods have failed.   Chemical euthanization refers to the use of chemicals to cause an easy or painless death and is divided into three categories: acute toxins, anticoagulants and decalcifiers, and fumigants. Acute toxins only require a single dose to kill animals, whereas anticoagulants and decalcifiers require numerous doses over time. Fumigants are used to suffocate animals underground. While this type of population control method poses ethical concerns, the World Society for the Protection of Animals (WSPA) believes it is necessary when human health or the safety of other animals are at risk.https://caninerabiesblueprint.org/IMG/pdf/Link72_Euthanasia_WSPA.pdf To ensure this control method is humane, WSPA states that it must be painless, achieve rapid unconsciousness followed by death, minimize animal fear and distress, and be reliable and irreversible. Population control also plays a significant role in managing and controlling invasive species so that they are eliminated before becoming abundant and causing any ecological harm.


Examples

Several efforts have been made to control the population of
tick Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s, which act as vectors of a number of diseases and therefore pose a risk to humans. Efforts are also continuously being made to control wildlife populations near airports. Specifically, control measures have been approved for bald eagles and deer.


See also

*
Animal trapping Animal trapping, or simply trapping or gin, is the use of a device to remotely catch an animal. Animals may be trapped for a variety of purposes, including food, the fur trade, hunting, pest control, and wildlife management. History Neolithi ...
*
Hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
*
Malthusianism Malthusianism is the idea that population growth is potentially exponential while the growth of the food supply or other resources is linear, which eventually reduces living standards to the point of triggering a population die off. This event, ...
*
Overpopulation in wild animals Overpopulation or overabundance is a phenomenon in which a species' population becomes larger than the carrying capacity of its environment. This may be caused by increased birth rates, lowered mortality rates, reduced predation or large scale m ...
* Trap-neuter-return for feral cats *
Wildlife management Wildlife management is the management process influencing interactions among and between wildlife, its habitats and people to achieve predefined impacts. It attempts to balance the needs of wildlife with the needs of people using the best availabl ...


References


Further reading

* {{DEFAULTSORT:Population Control Animal culling Animal welfare Birth control Population density