![At the drafting race from The Powerhouse Museum Collection](https://upload.wikimedia.org/wikipedia/commons/a/af/At_the_drafting_race_from_The_Powerhouse_Museum_Collection.jpg)
In
biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
, culling is the process of segregating organisms from a group according to desired or undesired characteristics. In
animal breeding
Animal breeding is a branch of animal science that addresses the evaluation (using best linear unbiased prediction and other methods) of the genetic value (estimated breeding value, EBV) of livestock. Selecting for breeding animals with superior E ...
, it is the process of removing or segregating animals from a breeding stock based on a specific trait. This is done to exaggerate desirable characteristics, or to remove undesirable characteristics by altering the genetic diversity of the population. For
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...
and
wildlife
Wildlife refers to undomesticated animal species, but has come to include all organisms that grow or live wild in an area without being introduced by humans. Wildlife was also synonymous to game: those birds and mammals that were hunted ...
, culling often refers to the act of
killing removed animals based on their individual characteristics, such as their sex or species membership, or as a means of preventing
infectious disease transmission.
In
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
s and
vegetable
Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, ...
s, culling is the sorting or segregation of fresh harvested produce into marketable lots, with the non-marketable lots being discarded or diverted into
food processing or non-food processing activities. This usually happens at collection centres located at, or close to farms.
Etymology
The word ''cull'' comes from the Latin verb ''
colligere'', meaning "to gather". The term can be applied broadly to mean partitioning a collection into two groups: one that will be kept and one that will be rejected. The cull is the set of items rejected during the selection process. The culling process is repeated until the selected group is of proper size and consistency desired.
Pedigreed animals
''Culling'' is:
In the breeding of
pedigreed
Purebreds are "cultivated varieties" of an animal species achieved through the process of selective breeding. When the lineage of a purebred animal is recorded, that animal is said to be " pedigreed". Purebreds breed true-to-type which means the ...
animals, both desirable and undesirable traits are considered when choosing which animals to retain for breeding and which to place as pets. The process of culling starts with examination of the conformation standard of the animal and will often include additional qualities such as health, robustness, temperament, color preference, etc. The breeder takes all things into consideration when envisioning their ideal for the breed or goal of their breeding program. From that vision, selections are made as to which animals, when bred, have the best chance of producing the ideal for the breed.
Breeders of pedigreed animals cull based on many criteria. The first culling criterion should always be health and robustness. Secondary to health, temperament and conformation of the animal should be considered. The filtering process ends with the breeder's personal aesthetic preferences on pattern, color, etc.
Tandem Method
The Tandem Method is a form of selective breeding where a breeder addresses one characteristic of the animal at a time, thus selecting only animals that measure above a certain threshold for that particular trait while keeping other traits constant. Once that level of quality in the single trait is achieved, the breeder will focus on a second trait and cull based on that quality.
[ With the tandem method, a minimum level of quality is set for important characteristics that the breeder wishes to remain constant. The breeder is focusing improvement in one particular trait without losing quality of the others. The breeder will raise the threshold for selection on this trait with each successive generation of progeny, thus ensuring improvement in this single characteristic of his breeding program.
For example, a breeder that is pleased with the muzzle length, muzzle shape, and eye placement in the breeding stock, but wishes to improve the eye shape of progeny produced may determine a minimum level of improvement in eye shape required for progeny to be returned into the breeding program. Progeny is first evaluated on the existing quality thresholds in place for muzzle length, muzzle shape, and eye placement with the additional criterion being improvement in eye shape. Any animal that does not meet this level of improvement in the eye shape while maintaining the other qualities is culled from the breeding program; i.e., that animal is not used for breeding, but is instead ]neutered
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. C ...
and placed in a pet home.
Independent levels
Independent levels is a method where any animal who falls below a given standard in any single characteristic is not used in a breeding program. With each successive mating, the threshold culling criteria are raised thus improving the breed with each successive generation.[
This method measures several characteristics at once. Should progeny fall below the desired quality in any one characteristic being measured, it will not be used in the breeding program regardless of the level of excellence of other traits. With each successive generation of progeny, the minimum quality of each characteristic is raised thus ensuring improvement of these traits.
For example, a breeder has a view of what the minimum requirements for muzzle length, muzzle shape, eye placement, and eye shape they are breeding toward. The breeder will determine what the minimum acceptable quality for each of these traits will be for progeny to be folded back into their breeding program. Any animal that fails to meet the quality threshold for any one of these criteria is culled from the breeding program.
]
Total score method
The total score method is a selection method where the breeder evaluates and selects breeding stock based on a weighted table of characteristics. The breeder selects qualities that are most important to them and assigns them a weight. The weights of all the traits should add up to 100. When evaluating an individual for selection, the breeder measures the traits on a scale of 1 to 10, with 10 being the most desirable expression and 1 being the lowest. The scores are then multiplied by their weights and then added together to give a total score. Individuals that fail to meet a threshold are culled (or removed) from the breeding program. The total score gives a breeder a way to evaluate multiple traits on an animal at the same time.[
The total score method is the most flexible of the three. it allows for weighted improvement of multiple characteristics. It allows the breeder to make major gains in one aspect while moderate or lesser gains in others.
For example, a breeder is willing to make a smaller improvement in muzzle length and muzzle shape in order to have a moderate gain in improvement of eye placement and a more dramatic improvement in eye shape. Suppose the breeder determines that she would like to see 40% improvement in eye shape, 30% improvement in eye placement, and 15% improvement in both muzzle length and shape. The breeder would evaluate these characteristics on a scale of 1 to 10 and multiply by the weights. The formula would look something like: 15 (muzzle length) + 15 (muzzle shape) + 30 (eye placement) + 40 (eye shape) = total score for that animal. The breeder determines the lowest acceptable total score for an animal to be folded back into their breeding program. Animals that do not meet this minimum total score are culled from the breeding program.
]
Livestock and production animals
Livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...
bred for the production of meat or milk may be culled by farmers. Animals not selected to remain for breeding are sold, killed, or sent to the slaughterhouse.
Criteria for culling livestock and production animals can be based on population or production (milk or egg). In a domestic or farming
Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...
situation, the culling process involves the selection and selling of surplus stock. The selection may be done to improve breeding stock—for example, for improved production of eggs or milk—or simply to control the group's population for environmental and species preservation. In order to increase the frequency of preferred phenotypes
In genetics, the phenotype () is the set of observable characteristics or phenotypic trait, traits of an organism. The term covers the organism's morphology (biology), morphology or physical form and structure, its Developmental biology, dev ...
, agricultural practices typically involve using the most productive animals as breeding stock.
With dairy cattle, culling may be practised by inseminating cows—considered to be inferior—with beef breed semen and by selling the produced offspring for meat production.
Approximately half of the chicks of egg-laying chickens are males who would grow up to be roosters. These individuals have little use in an industrial egg-producing facility as they do not lay eggs, so the majority of male chicks are killed shortly after hatching.
Culling of farmed animals is considered a necessary practice to prevent the spread of damaging and fatal diseases such as foot-and-mouth disease, avian flu
Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds. , Influenza A virus subtype H5N1
Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus which can cause illness in humans and many other animal species. A bird-adapted strain of H5N1, called HPAI A(H5N1) for highly pathogenic avian influenza virus of type ...
and bovine spongiform encephalopathy
Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is an incurable and invariably fatal neurodegenerative disease of cattle. Symptoms include abnormal behavior, trouble walking, and weight loss. Later in the course of t ...
("mad cow disease").
Wildlife
In the United States, hunting licenses and hunting seasons are a means by which the population of game animals is maintained. Each season, a hunter is allowed to kill a certain amount of wild animals, determined both by species and sex. If the population seems to have surplus females, hunters are allowed to take more females during that hunting season. If the population is below what is desired, hunters may not be permitted to hunt that particular species, or only hunt a restricted number of males.
Populations of game animals such as elk
The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
may be informally culled if they begin to excessively eat winter food set out for domestic cattle herds. In such instances the rancher will inform hunters that they may hunt on their property in order to thin the wild herd to controllable levels. These efforts are aimed to counter excessive depletion of the winter feed supplies. Other managed culling instances involve extended issuance of extra hunting licenses, or the inclusion of additional "special hunting seasons" during harsh winters or overpopulation periods, governed by state fish and game agencies.
Culling for population control is common in wildlife management, particularly on Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
n game farm
A game farm is a place where game animals are raised to stock wildlife areas for hunting. The term also includes places where such animals are raised to be sold as food or for photography. Their existence has been exemplified within the South Afr ...
s and Australian national parks. In the case of very large animals such as elephants, adults are often targeted. Their orphaned young, easily captured and transported, are then relocated to other reserves. Culling is controversial in many African countries, but reintroduction of the practice has been recommended in recent years for use at the Kruger National Park in South Africa
South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...
, which has experienced a swell in its elephant population since culling was banned in 1995.
Arguments against wildlife culling
Culling acts as a strong selection force and can therefore impact the population genetics
Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as Adaptation (biology), adaptation, ...
of a species. For example, culling based on specific traits, such as size, can enforce directional selection
In population genetics, directional selection, is a mode of negative natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. Under dir ...
and remove those traits from the population. This can have long-term effects on the genetic diversity of a population.
Additionally, culling can act as a selection force intentionally implemented by humans to counteract the selection force of trophy hunting
Trophy hunting is a form of hunting for sport in which parts of the hunted wild animals are kept and displayed as trophies. The animal being targeted, known as the " game", is typically a mature male specimen from a popular species of collectab ...
. Hunting typically enforces selection towards unfavorable phenotypic traits because of the strong hunting bias for specific traits, such as large antler size. Culling "low-quality" traits can counteract this force.
Animal rights
Animal rights is the philosophy according to which many or all Animal consciousness, sentient animals have moral worth that is independent of their Utilitarianism, utility for humans, and that their most basic interests—such as avoiding s ...
activists argue that killing animals for any reason (including hunting) is cruel and unethical.
Birds
Some bird species are culled when their populations impact upon human property, business or recreational activity, disturb or modify habitats or otherwise impact species of conservation concern. Cormorants are culled in many countries due to their impact on commercial and recreational fisheries and habitat modification for nesting and guano deposition. They are culled by shooting and the smothering of eggs with oil. Another example is the culling of silver gull
The silver gull (''Chroicocephalus novaehollandiae'') is the most common gull of Australia. It has been found throughout the continent, but particularly at or near coastal areas. It is smaller than the Pacific gull (''Larus pacificus''), which ...
s in order to protect the chicks of the vulnerable banded stilt
The banded stilt (''Cladorhynchus leucocephalus'') is a nomadic wader of the stilt and avocet family, Recurvirostridae, native to Australia. It belongs to the monotypic genus ''Cladorhynchus''. It gets its name from the red-brown breast band fo ...
at ephemeral inland salt lake breeding sites in South Australia. The gulls were culled using bread laced with a narcotic substance. In the Australian states of Tasmania and South Australia, Cape Barren geese
The Cape Barren goose (''Cereopsis novaehollandiae'') is a large goose resident in southern Australia.
Etymology
The species' common name is derived from Cape Barren Island, where specimens were first sighted by European explorers. It is known ...
are culled to limit damage to crops and the fouling of waterholes. Cape Barren Geese remain one of the rarest geese in the world, though much of their habitat is now regarded as secure.
Seals
In South Australia
South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
, the recovery of the state's native population of New Zealand fur seals (''Arctocephalus forsteri
''Arctocephalus forsteri'' (common names include the Australasian fur seal, South Australian fur seal, New Zealand fur seal, Antipodean fur seal, or long-nosed fur seal) is a species of fur seal found mainly around southern Australia and New Z ...
'') after severe depletion by sealers in the 1800s has brought them into conflict with the fishing industry. This has prompted members of Parliament to call for seal culling in South Australia. The State Government continues to resist the pressure and as of July 2015, the animals remain protected as listed Marine Mammals under the state's ''National Parks and Wildlife Act 1972
Protected areas of South Australia consists of protected areas located within South Australia and its immediate onshore waters and which are managed by South Australian Government agencies. As of March 2018, South Australia contains 359 sepa ...
''.
Sharks
Shark culling occurs in four locations : New South Wales
)
, nickname =
, image_map = New South Wales in Australia.svg
, map_caption = Location of New South Wales in AustraliaCoordinates:
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, es ...
, Queensland
)
, nickname = Sunshine State
, image_map = Queensland in Australia.svg
, map_caption = Location of Queensland in Australia
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, establishe ...
, KwaZulu-Natal and Réunion. Between 1950 and 2008, 352 tiger sharks and 577 great white sharks were killed in the nets in New South Wales—also during this period, a total of 15,135 marine animals were caught and killed in the nets, including whales, turtles, rays, dolphins, and dugongs. From 2001 to 2018, a total of 10,480 sharks were killed on lethal drum lines
A drum line is an unmanned aquatic trap used to lure and capture large sharks using baited hooks. They are typically deployed near popular swimming beaches with the intention of reducing the number of sharks in the vicinity and therefore the prob ...
in Queensland. In a 30-year period up to early 2017, more than 33,000 sharks were killed in KwaZulu-Natal's shark-killing program—during the same 30-year period, 2,211 turtles, 8,448 rays, and 2,310 dolphins were killed. Authorities on Réunion kill about 100 sharks per year. All of these culls have been criticized by environmentalists, who say killing sharks harms the marine ecosystem
Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the sur ...
.
In 2014, a controversial policy was introduced by the Western Australia
Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...
n state government which became known as the Western Australian shark cull
The Western Australian shark cull is the common term for a former state government policy of capturing and killing large sharks ( shark culling) in the vicinity of swimming beaches by use of baited drum lines. The policy was implemented in 20 ...
. Baited hooks known as drum lines
A drum line is an unmanned aquatic trap used to lure and capture large sharks using baited hooks. They are typically deployed near popular swimming beaches with the intention of reducing the number of sharks in the vicinity and therefore the prob ...
were to be set over several consecutive summers to catch and kill otherwise protected great white sharks
The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocean ...
. The policy's objective was to protect users of the marine environment from fatal shark attack. Thousands of people protested against its implementation, claiming that it was indiscriminate, inhumane and worked against scientific advice the government had previously received. Seasonal setting of drum lines was abandoned in September 2014 after the program failed to catch any great white sharks, instead catching 172 other elasmobranchii
Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including sharks (superorder Selachii), rays, skates, and sawfish (superorder Batoidea). Members of this subclass are characterised by having five to seven pairs of ...
, mostly tiger sharks.
Deer
White-tailed deer
The white-tailed deer (''Odocoileus virginianus''), also known as the whitetail or Virginia deer, is a medium-sized deer native to North America, Central America, and South America as far south as Peru and Bolivia. It has also been introduced t ...
(''Odocoileus virginianus'') have been becoming an issue in suburbs across the United States of America due to large population increases. This is thought to be caused mainly by the extirpation
Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...
of most of their major predators in these areas. In response to these population booms, different management approaches have been taken to decrease their numbers mainly in the form of culls. Culls of deer are often partnered with exclusions with fencing and also administering contraceptives.
The effectiveness of these deer culls has been debated and often criticized as only a temporary fix to the larger problem of deer overpopulation and argue that the use of culling will increase fertility of remaining deer by reducing competition. Those in favor of the culls argue that they can be used to combat the selection pressure
Any cause that reduces or increases reproductive success in a portion of a population potentially exerts evolutionary pressure, selective pressure or selection pressure, driving natural selection. It is a quantitative description of the amount of ...
that is imposed by hunting that creates smaller antler and body sizes in deer. People in favor of the culls recommend that they not be random and actively select for smaller individuals and bucks with smaller antlers, specifically "button bucks" or bucks with only spiked antler in their first year as opposed to forked antlers.
Culling of deer can also have benefits in the form of disease prevention and in places that the white-tailed deer is an invasive species such as New Zealand culling of deer has added benefits for native species. Diseases are density dependent factors and decreases in the density of the deer populations through culling causes diseases, such as chronic wasting disease
Chronic wasting disease (CWD), sometimes called zombie deer disease, is a transmissible spongiform encephalopathy (TSE) affecting deer. TSEs are a family of diseases thought to be caused by misfolded proteins called prions and include similar dis ...
and Lyme disease
Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the ''Borrelia'' bacterium, which is spread by ticks in the genus ''Ixodes''. The most common sign of infection is an expanding red rash, known as erythema migran ...
, to spread less quickly and effectively.
Zoos
Many zoo
A zoo (short for zoological garden; also called an animal park or menagerie) is a facility in which animals are kept within enclosures for public exhibition and often bred for conservation purposes.
The term ''zoological garden'' refers to zoo ...
s participate in an international breeding program
A breeding program is the planned breeding of a group of animals or plants, usually involving at least several individuals and extending over several generations. There are a couple of breeding methods, such as artificial (which is man made) and ...
to maintain a genetically viable population and prevent inbreeding. Animals that can no longer contribute to the breeding program are considered less desirable and are often replaced by more desirable individuals. If an animal is surplus to a zoo's requirements and a place in another zoo can not be found, the animal may be killed. In 2014, the culling of a young, healthy giraffe Marius raised an international public controversy.
Zoos sometimes consider female animals to be more desirable than males. One reason for this is that while individual males can contribute to the birth of many young in a short period of time, females give birth to only a few young and are pregnant for a relatively long period of time. This makes it possible to keep many females with just one or two males, but not the reverse. Another reason is that the birth of some animal species increases public interest in the zoo.
Germany's ''Animal Welfare Act 1972'' orders that zoo animals cannot be culled without verification by official veterinary institutes of the Landkreis
In all German states, except for the three city states, the primary administrative subdivision higher than a '' Gemeinde'' (municipality) is the (official term in all but two states) or (official term in the states of North Rhine-Westphalia ...
or federated state
A federated state (which may also be referred to as a state, a province, a region, a canton, a land, a governorate, an oblast, an emirate or a country) is a territorial and constitutional community forming part of a federation. Such states d ...
.
In the UK, there is no general prohibition on 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 ...
, which is allowed when overcrowding compromises the well-being of the animals.
Ethics
Jaak Panksepp
Jaak Panksepp (June 5, 1943 – April 18, 2017) was an Estonian-American neuroscientist and psychobiologist who coined the term " affective neuroscience", the name for the field that studies the neural mechanisms of emotion. He was the Baily End ...
, an American neuroscientist, concludes that both animals and humans have brains wired to feel emotions, and that animals have the capacity to experience pleasure and happiness from their lives.
Culling has been criticized on animal rights grounds as speciesist
Speciesism () is a term used in philosophy regarding the treatment of individuals of different species. The term has several different definitions within the relevant literature. A common element of most definitions is that speciesism involves t ...
—it has been argued that killing animals for any reason is cruel and unethical, and that animals have a right to live.
Some argue that culling is necessary when biodiversity
Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
is threatened. However, the protection of biodiversity argument has been questioned by some animal rights advocates who point out that the animal which most greatly threatens and damages biodiversity is humanity, so if we are not willing to cull our own species we cannot morally justify culling another.
Non-lethal alternatives
There are non-lethal alternatives which may still be considered culling, and serve the same purpose of reducing population numbers and selecting for desired traits without killing existing members of the population. These methods include the use of wildlife contraceptive
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 ...
s and reproductive inhibitors. By using such methods population numbers might be reduced more gradually and in a potentially more humane fashion than by directly lethal culling actions.
Currently, wildlife contraceptives are largely in the experimental phase and include such products as Gonacon, an adjuvant In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to:
* Adjuvant therapy in cancer management
* Analgesi ...
vaccine which delivers a high dosage of a competitor ligand of the hormone
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are require ...
GnRH
Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and releas ...
to female mammals (e.g. whitetail deer). The complex formed of GnRH and the Gonacon molecule promotes production of antibodies against the animal's own GnRH, which themselves complex with GnRH. This encourages an extended duration of the drug's effects (namely, reduction of active/unbound GnRH in the animal's system). Though the endocrinology
Endocrinology (from '' endocrine'' + '' -ology'') is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as hormones. It is also concerned with the integration of developmental event ...
behind Gonacon is sound, the need for multiple lifetime doses for full efficacy make it a less-guaranteed and less-permanent solution for wildlife than lethal culls. Even among domestic animals in controlled conditions, Gonacon cannot ensure 100% reduction in the occurrence of pregnancies.
Reproductive inhibitors need not act on the parental individuals directly, instead damaging reproductive processes and/or developing offspring to reduce the number of viable offspring per mating pair. One such compound called Nicarbazin
Nicarbazin is a coccidiostat used on meat chickens. It is also used as a contraceptive for population control of Canada geese and feral pigeons.
It is also a wide-spectrum anti-parasitic drug approved for veterinary use, effective on ''Toxocar ...
has been formulated into bait for consumption by Canada Geese
The Canada goose (''Branta canadensis''), or Canadian goose, is a large wild goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is o ...
, and damages egg yolk formation to reduce the viability of clutches without harming the adult geese.
See also
* Badger culling in the United Kingdom
Badger culling in the United Kingdom is permitted under licence, within a set area and timescale, as a way to reduce badger numbers in the hope of controlling the spread of bovine tuberculosis (bTB).
Humans can catch bTB, but public health con ...
* Brumby
A brumby is a free-roaming feral horse in Australia. Although found in many areas around the country, the best-known brumbies are found in the Australian Alps region. Today, most of them are found in the Northern Territory, with the second ...
- feral horse
A feral horse is a free-roaming horse of domesticated stock. As such, a feral horse is not a wild animal in the sense of an animal without domesticated ancestors. However, some populations of feral horses are managed as wildlife, and these ...
s in Australia
* Eugenics
Eugenics ( ; ) is a fringe set of beliefs and practices that aim to improve the genetic quality of a human population. Historically, eugenicists have attempted to alter human gene pools by excluding people and groups judged to be inferior o ...
, the selective breeding of human populations
* Experimental evolution
Experimental evolution is the use of laboratory experiments or controlled field manipulations to explore evolutionary dynamics. Evolution may be observed in the laboratory as individuals/populations adapt to new environmental conditions by natura ...
* Feral camels in Australia
Australian feral camels are feral populations of dromedaries (''Camelus dromedarius'') in Australia. Imported from British India and Afghanistan during the 19th century for transport and construction during the colonisation of the central an ...
* Feral cats in Australia
Cats are an invasive species in Australia. Because they are not native to Australia and were only introduced by colonisers as pets in the early 1800s, native Australian animals did not co-evolve with them. , some 3.8 million domestic cats and u ...
References
External links
Dictionary.com definition for Culling
{{Animal rights
Animal culling
Animal killing
Animal rights
Animal welfare
Cruelty to animals
Intensive farming
Livestock