Interbreeding of dingoes with other domestic dogs
Encyclopedia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. The current population of free ranging domestic dogs in Australia is now probably higher than in the past. However, the proportion of the so-called "pure" dingo
Dingo
The Australian Dingo or Warrigal is a free-roaming wild dog unique to the continent of Australia, mainly found in the outback. Its original ancestors are thought to have arrived with humans from southeast Asia thousands of years ago, when dogs were still relatively undomesticated and closer to...
es (dogs with exclusively dingo-ancestry) has been in the decrease over the last few decades and is regarded as further decreasing.
Because of this ongoing interbreeding of dingoes and other domestic dogs and the resulting hybrid
Mixed-breed dog
A mixed-breed dog, also known as a mutt or mongrel, is a dog whose ancestry is generally unknown and that has characteristics of two or more types of breeds. A mixed-breed may be a cross-breed dog, a random-bred dog, or a descendant of feral or pariah dog populations...
s, there is a much wider range of colours and body shapes today among the Australian wild dog population than in the time before the European colonization
History of Australia
The History of Australia refers to the history of the area and people of Commonwealth of Australia and its preceding Indigenous and colonial societies. Aboriginal Australians are believed to have first arrived on the Australian mainland by boat from the Indonesian archipelago between 40,000 to...
. The full extent of the impacts of this process is currently unknown and the possibility of potential problems, as well as the wish to preserve the "pure" dingo, often leads to a strong rejection of the interbreeding.
Causes, degree, and forms of interbreeding
According to present knowledge, the dingo arrived in Australia together with seafarers four millennia ago, and reverted to the wild there. The dingo has been proven to have existed on the continent for at least 3,500 years, which was confirmed by archaeological as well as genetic examinations and findings. Additionally, it was suspected that there was later no significant introduction of other domestic dogs before the arrival of the Europeans.European domestic dogs arrived in Australia in the 18th century, the European colonization. Since then, some of those dogs dispersed into the wild (both deliberately and accidentally) and founded feral populations, especially in places where the dingo numbers had been severely reduced due to human intervention. Although there are few records of such releases, their occurrence is supported by reports of free-living dogs of specific breeds being seen or captured in remote areas. The spread of farming and grazing activities in the 19th century led to a further spread of other domestic dogs, both pet and feral ones. Interbreeding with the native dingoes has probably been occurring since the arrival of other domestic dogs in the year 1788.
Causes and forms
Interbreeding of dingoes and other domestic dogs is not necessarily unintended and dingoes have been used for the breeding of certain dog breed
Dog breed
Dog breeds are groups of closely related and visibly similar domestic dogs, which are all of the subspecies Canis lupus familiaris, having characteristic traits that are selected and maintained by humans, bred from a known foundation stock....
s. These breeding attempts already started in the 19th century. The only attempt to date that was regarded as successful was the breeding of the Australian Cattle Dog
Australian Cattle Dog
The Australian Cattle Dog is a breed of herding dog originally developed in Australia for droving cattle over long distances across rough terrain. In the 19th century, New South Wales cattle farmer Thomas Hall crossed the dogs used by drovers in his parents' home county, Northumberland, with...
. It is possible that the Australian Kelpie
Australian Kelpie
The Kelpie is an Australian sheep dog successful at mustering and droving with little or no command guidance. They are medium-sized dogs and come in a variety of colours...
is descended from dingoes too, however that has not been proven.
Occasionally claims are made that interbreeding of dingoes and other domestic dogs together with successful rearing of hybrids is a rare phenomenon in the wild due to supposedly radical differences in behaviour and biology and the harshness of the wilderness. However, cases of dogs that came from human households but nonetheless manage to survive on their own (even by active hunting) and to successfully rear pups have been consistently proven. German behaviourist Eberhard Trumler (who is regarded as a nestor of cynology in the German speaking area) believed that cross-breeds of dingoes and shepherd dogs might have good chances of surviving in the wild. In addition Alfred Brehm
Alfred Brehm
Alfred Edmund Brehm was aGerman zoologist, natural history illustrator and writer, the son ofChristian Ludwig Brehm....
already reported of interbreeding of dingoes and other domestic dogs of both sexes. There are even reports of dingo-like wild dogs mating with restrained female domestic dogs.
Urban area
An urban area is characterized by higher population density and vast human features in comparison to areas surrounding it. Urban areas may be cities, towns or conurbations, but the term is not commonly extended to rural settlements such as villages and hamlets.Urban areas are created and further...
centres, due to the prospect of easily accessible food resources. However, since interactions between dingoes and other feral domestic dogs in the bush differ greatly from those in urban places, so too do the rates of hybridisation. It is known that domestic dogs get lost in the bush time and again. However; it is assumed that the behavioural differences between dingoes and other domestic dogs are big enough to make it difficult for these dogs to be integrated into dingo-society and successfully breed, especially in remote areas. A further spreading of hybrids might hasten the process of interbreeding by reducing behavioural differences. This could partially explain the higher proportion of dingo-hybrids in Southeast Australia. The most likely possibility is that the territorial behaviour
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
of established dingo-packs, which keeps away all foreign dogs (dingoes included) and prevents them from breeding, curbs the rate of interbreeding. Dingoes owned by humans as pets are likely to use their owner’s home as a base from which to roam, or are abandoned when they reach adulthood. The result of this pet trend is that contacts between dingoes and other domestic dogs are increasing; because pet dingoes grow up without learning the social behaviours that curb mating and therefore crossbreeding. Many such hybrids are rejected by owners or stray to the bush where they may breed with “pure” dingoes. In addition it is proven that hybrids can appear when dingoes mate with livestock guardian dogs; interbreeding can even occur with dogs that were acquired by their owners to specifically kill dingoes.
There is currently no evidence that the known measures for the control of dingoes and other wild dogs are effectively able to slow the process of interbreeding. It seems rather to be that these controls hasten the process of interbreeding since it breaks up traditional pack structures and therefore causes some mechanisms of population control
Population control
Human population control is the practice of artificially altering the rate of growth of a human population.Historically, human population control has been implemented by limiting the population's birth rate, usually by government mandate, and has been undertaken as a response to factors including...
to disappear.
Degree of interbreeding
Dingo-samples that have been collected in the 1960s and 1970s indicated that half of the wild dogs of southern AustraliaSouthern Australia
The term southern Australia is generally considered to include the States and territories of Australia of New South Wales, Victoria, South Australia, Tasmania and the Australian Capital Territory...
were dingo-hybrids; analyses from the early 1980s supported the trend of increasing interbreeding. Based on skull features researchers found out that the proportion of “pure” dingoes in the highlands of the Southeast decreased from 49% in the 1960s to 17% in the 1980s. During examinations in the year 1985 in Southeast-Australia only 55% of the 407 studied “dingoes” weren’t hybrids. 36% of the dogs were dingo-hybrids and the rest wild dogs of other origin. In the middle of the 1980s the proportion of “pure” dingoes respectively dingo-hybrids in Central Australia
Central Australia
Central Australia/Alice Springs Region is one of the five regions in the Northern Territory. The term Central Australia is used to describe an area centred on Alice Springs in Australia. It is sometimes referred to as Centralia; likewise the people of the area are sometimes called Centralians...
was estimated (based on skull features) to be 97.5% and 2.4%. To the contrary, in Southeast-Australia the estimates were 55.3% respectively 33.92%. It was reasoned from these findings that mixed populations can be expected in areas were human settlements exist and wild dogs remain, furthermore that hybrids can be expected to be rarer in remote areas. Broken colour-patterns, red with white, black or bluish spots, completely black, brown or bluish, black-and-white and piebald striped patterns were also more prevalent in the second area (34.8%) than in the first (5.7%). In Southeast-Australia there were no differences between areas near farmlands and forest concerning the frequency of the colorations. Many of these colorations also occurred in breeding experiments of reddish dingoes with variously colored other domestic dogs. All in all about 50% of the populations in Eastern and Southern Australia consisted of hybrids in the 1980s. Depending on the area in Southeast-Australia it was estimated that the proportion of “pure” dingoes was at least 22% and at its most 65%. 100 dog skulls from the Queensland Museum
Queensland Museum
The Queensland Museum is the state museum of Queensland. The museum currently operates four separate campuses; at South Brisbane, Ipswich, Toowoomba and Townsville.The museum is funded by the State Government of Queensland.-History:...
were measured and analysed, to determine the frequency of dingoes in the dog-populations of Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
. The highest frequency of dingoes (95%) was found among skulls from central Queensland
Central Queensland
Central Queensland is an ambiguous geographical division of Queensland that centres on the eastern coast, around the Tropic of Capricorn. Its major regional centre is Rockhampton and the Capricorn Coast and the area extends west to the Central Highlands at Emerald, north to the Mackay Regional...
and the highest frequency of other domestic dogs and dingo-hybrids (50%) was found in the Southeast of the state. Fraser Island had only a low frequency of hybrids (17%) that were mostly limited to the southern half of the island. It was estimated back then that the proportion of dingo-hybrids in the continent-wide population was about 78%. At the turn of the millennium only 74% of 180 skulls from seven main areas of Australia could be classified as dingo-skulls during measurements and none of the populations consisted exclusively of dingoes. According to Laurie Corbett some examined wild dog populations in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
consisted entirely of hybrids.
Kakadu National Park
Kakadu National Park is in the Northern Territory of Australia, 171 km southeast of Darwin.Kakadu National Park is located within the Alligator Rivers Region of the Northern Territory of Australia. It covers an area of , extending nearly 200 kilometres from north to south and over 100 kilometres...
or parts of the Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
, dingo-hybrids now exist respectively appear on the border zones of bush and settlements. In addition, hybrids have been spotted in northern Australia
Northern Australia
The term northern Australia is generally known to include two State and Territories, being Queensland and the Northern Territory . The part of Western Australia north of latitude 26° south—a definition widely used in law and State government policy—is also usually included...
and in remote regions.
According to some sources, the dog population of Southeast Australia and along the East Coast now consists to 90% of dingo-hybrids, other sources state that the dog population along the East Coast consists to 80% of hybrids and only 15% to 20% of the dingoes in Southeast-Australia and South-Queensland are supposed to be “pure”. In the Southwest of Australia and the interior of Queensland the 90-95% of the dingoes might be “pure“. Genetic analyses during the last years came to the conclusion that the populations of wild dogs in the southern Blue Mountains consists of 96.8% dingo-hybrids. The statements (respectively estimations) on how many dingo-hybrids there are in the whole of Australia are very high but not homogeneous. Sometimes statements appear saying that most populations contain 80% hybrids or that 80% or 90% of all Australian wild dogs are dingo-hybrids.
However, these hybrids don’t necessarily have to be of low dingo-content. During an analysis of 56 wild dogs in Southeast-Queensland the researchers found that these dogs had a dingo-content of more than 50% or were “pure” dingoes. “Pure” feral dogs of other origin or hybrids with low dingo-content could not be found. Therefore it was reasoned that the wild dogs of Brisbane
Brisbane
Brisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...
and the Sunshine Coast
Sunshine Coast, Queensland
The Sunshine Coast is an urban area in South East Queensland, north of the state capital of Brisbane on the Pacific Ocean coastline. Although it does not have a central business district, by population it ranks as the 10th largest metropolis in Australia and the third largest in...
are the descendents of dingoes, instead of escaped or rejected dogs. During studies on wild dogs of the Kosciuszko national park
Kosciuszko National Park
Kosciuszko National Park covers 690,000 hectares and contains mainland Australia's highest peak, Mount Kosciuszko for which it is named, and Cabramurra the highest town in Australia...
, many hybrids were found but these dogs were of relatively high dingo-content.
Identification of dingo-hybrids
There are a couple of external features that can be used to distinguish “pure” dingoes from other “pure” domestic dogs. However this might not be the case when concerning mixed-breed dogs and especially dingo-hybrids.Distinguishing characteristics
Dingo-like domestic dogs and dingo-hybrids can be generally distinguished from “pure” dingoes because of coat colour, since they have a wider range of colours and patterns than dingoes. Additionally the dog-typical form of barking appears among dingo-hybrids.
Nasal bone
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, "the bridge" of the nose.Each has two surfaces and four borders....
s.
To determine the possibility of dingo-hybrids in the wild, hybrids were bred in captivity in the 1970s and the start of the 1980s. Thereby differences in skull features were all the bigger the nearer the hybrid was genetically to other domestic dogs. Even a non-dingo content of about 25% to 12.5% lead to a significant difference when compared to the 8 dingo parents.
Unlike dingoes other feral domestic dogs and dingo-hybrids are theoretically capable two come in heat twice annually and tend to have a breeding cycle less influenced by the seasons. However, it is considered to be unlikely that they are capable of rearing two litters per year in the wild since this would require much time and energy. Successful rearing of two successive litters would probably only be possible in the wild under very favourable conditions and there is currently no proof that it ever happened in the wild.
During observation at the start of the 1990s captive hybrids did not show the same breeding pattern like “pure” dingoes and many testicle
Testicle
The testicle is the male gonad in animals. Like the ovaries to which they are homologous, testes are components of both the reproductive system and the endocrine system...
-parameters did not show the same seasonal variations. Furthermore they had bigger litters and some were able to reproduce over the whole year. Concerning the duration of the pregnancy there was no evidence for any differences.
Although hybrids may have a weight up to 60 kg (supposedly even up to 70 kg), most hybrids do not weigh more than 20 kg, which is considered to be within the normal range for dingoes. Furthermore during breeding-experiments there could be no differences in growth patterns of dingoes and similar sized crossbreeds found. Additionally, the average age of wild living domestic dogs in Australia is also not higher than what is considered normal for dingoes.
A genetic discrimination
Genetic discrimination
Genetic discrimination occurs when people are treated differently by their employer or insurance company because they have a gene mutation that causes or increases the risk of an inherited disorder. People who undergo genetic testing may be at risk for genetic discrimination.The results of a...
is possible but difficult, since there are only a few genetic characteristics that differentiate dingoes from other domestic dogs. A couple of years ago, some scientists from the University of New South Wales
University of New South Wales
The University of New South Wales , is a research-focused university based in Kensington, a suburb in Sydney, New South Wales, Australia...
developed a relatively reliable method with 20 genetic “fingerprints” using DNA-Material of skin and blood-samples to determine the “purity” of a dingo. If one of these “fingerprints” would be found, this would indicate that the examined dog is possibly a hybrid and not a “pure” dingo. The reference group for this test was a group of captive dingoes, thought to cover the whole range of the dingo population. Samples that lay outside of this range would be regarded as hybrids. With increasing development this method might be possible to use on hair and scat-samples and provide more exact results.
Problems with identification
Despite all the characteristics that may be used to differentiate a dingo from other domestic dogs, there are several problems that should not be underestimated.To break the first ground there is the fact that there is no clarity on the subject from which point on a dog is considered a “pure” dingo. There are conflicting opinions in literature on what defines a dingo. The following problems occurred frequently:
- Geographic variations in the allometry of dingo skulls were not taken into account, when dingoes from Central Australia were used as standard for the “purity” of dingoes
- Genetic variations of dingoes in captivity were not taken into account, when the genetic markerGenetic markerA genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify cells, individuals or species. It can be described as a variation that can be observed...
s for “purity” were selected - Methods for the collection of samples, to determine a dingo via genetic testingGenetic testingGenetic testing is among the newest and most sophisticated of techniques used to test for genetic disorders which involves direct examination of the DNA molecule itself. Other genetic tests include biochemical tests for such gene products as enzymes and other proteins and for microscopic...
, are susceptible for flaws in the identification (e.g. mistakes during collecting of the samples) - Microsatellites have been used to determine the “purity”; however an examination of microsatellite data indicated that they are only useful for making conclusion on relatedness
- newly research results show, that chemicals can influence the gene expressionGene expressionGene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...
and development of the neural crestNeural crestNeural crest cells are a transient, multipotent, migratory cell population unique to vertebrates that gives rise to a diverse cell lineage including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia....
during the early stages of the embryonic developmentEmbryogenesisEmbryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...
From this data it was reasoned that characteristics of dingoes from geographic isolated areas differ from each other and different populations might not be consistent with common description of a dingo.
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
. Biology and behaviour of dingoes and other wild dogs are generally considered to be so similar, that it is difficult to discriminate between them. Furthermore much of the information on dingoes might just as likely apply to any other wild dog in Australia. In addition, the external characteristics of living dingoes cannot always be reliably distinguished from dingo-hybrids; since many hybrids are visually indistinguishable from “pure” dingoes (e.g. hybrids resulting from mating with Australian Cattle Dogs). Even the colour variations, which are regarded as characteristics of the “pure” dingo, can be a hindrance when identifying hybrids and other domestic dogs, when they show the same colourations. Furthermore historical records report black dingoes but did not mention black-and-tan ones. This colouration might have been overlooked; if not than this would be another feature of hybrids. During breeding experiments with dingoes and other domestic dogs, dogs were born that could not be distinguished from dingoes based on external features but had two heat-cycles annually even down to the third and fourth generation. In the case of skull features there is the problem that they don’t discriminate between the different degrees of dingo-content in the hybrids, are less and less effective the further the hybrid is genetically away from other domestic dogs and can only be used on already dead specimen. Methods like X-ray and CAT-Scans are possible, but impractical. Also signs of dingo attacks on livestock aren’t reliable as a distinguishing characteristic, since the attack methods and the success rate possible depends the most from the experience and motivation of the attacker and the reactions of the prey.
Although genetic testing can theoretically determine whether an individual is a hybrid, “pure” dingo or another domestic dog; mistakes respectively false results cannot be excluded. To get reliable data from genetic testing, suitable and sufficient genetic material from the period before the European colonization should be available for comparison, which is currently not the case (state of knowledge in 2006). Even genetic testing is less effective, the further away the non-dingo is in the dogs ancestry and it is possible that the hybrid had not inherited any genes which were ascribed to other domestic dogs during examinations. Furthermore, even in the case of a “pure” dingo, genetic testing might show results that were not present in the used reference group.
Besides, the different methods for identification of hybrids (DNA, skull features and fur colour) can lead to different results that might be in conflict with each other. During the before mentioned analysis of 56 wild dogs in Southeast-Queensland there were only 17.9% conformity between the three used methods for determine the “purity”. The conformity between DNA and skull features was lowest. During this a hitherto unknown form of the “pure” dingo was discovered (based on DNA and skull features): a white dog with orange spots on the fur. This variant was considered as a single mutation or the result of interbreeding with an isolated dingo population.
Contrary to constantly recurring claims of radical differences in behaviour and biology, a single annual breeding cycle, seasonal adapted oestrus, monogamy, parental care by the males, regulation of breeding via ecological and social factors, and howling have all been observed among domestic dogs of most diverse backgrounds. In fact howling is considered normal for all wild dogs of Australia. Hybrids as well as other domestic dogs have been observed in tight pack structures and free-ranging domestic dogs in Southeast-Australia have been observed hunting and foraging in groups. Free-ranging dogs in Victoria were generally observed in pairs (54%) or alone (34%), with packs of three to seven dogs in 12% of the sightings. Furthermore there are also reports of dingoes with more than average size and weight and cases where hybrids were successfully used as working and companion dogs and the Australian Cattle Dog was proven to have dingo-ancestors. A generally higher aggression of hybrids could not be confirmed by owners, who worked with respectively investigated them; furthermore hitherto observations and encounters with hybrids in the wild did not reveal any evidence, that hybrids are generally more aggressive than “pure” dingoes.
Importance and impact of interbreeding
Interbreeding with other domestic dogs is regarded as the greatest threat to the survival of the “pure” dingo. Genetic analyses, observations and skull measurements over the course of several years strongly indicate that in approximately 50 years the “pure” dingo will have disappeared in the wilderness of the continent and that it is no longer possible to preserve them there. The dingo researcher Laurie Corbett considers that, given the current rate of interbreeding, there will be no more “pure” dingoes in the wilderness of Victoria in 20 years. The president of the Dingo Conservation Association Barry Oakman was in an interview in the year 2003 of the opinion that without appropriate measures the “pure” dingo would be extinct in the wild in 30 years, in New South Wales possibly in less than 10 years. According to other statements the “pure” dingoes are either close to extinction or they will be close to it over the course of the next 20 years. It is assumed that, should the process go on unhindered, the increasing number of genes from other domestic dogs will effectively lead to the extinction on the Australian continent of the dingo as a separate subspecies by 2100 and that the dog population will then consist of hybrids and other feral dogs.Opinions about this phenomenon
Fear of interbreeding of dingoes with other domestic dogs is no phenomenon of the last years and already led to a ban on the import of German Shepherd DogGerman Shepherd Dog
The German Shepherd Dog , also known as an Alsatian or just the German Shepherd, is a breed of large-sized dog that originated in Germany. The German Shepherd is a relatively new breed of dog, with its origin dating to 1899. As part of the Herding Group, the German Shepherd is a working dog...
s to Australia by the Commonwealth of Nations
Commonwealth of Nations
The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...
in 1929. It was feared that the German Shepherds (partly due to the old Name “Alsatian Wolfdog”) would be a danger to sheep, become friendly with dingoes and possibly interbreed with them. This ban was first relaxed in 1972 and repealed in 1974.
This phenomenon is a problem for some people and for others not. In the scientific area there two main positions concerning the process of interbreeding:
- The “pure” dingo should be preserved
- Populations of wild dogs should be preserved, no matter whether they are hybrids or not.
The first position is probably the most common one. It means that the “pure” dingo should be preserved via strong control measures and only “pure” or mostly “pure” dingoes should get protection.
The second position is relatively new and was first officially stated by Laurie Corbett and Mike J. Daniels. They represented the opinion that you have to accept that the dingoes have changed and that it is not possible to bring the “pure” dingo back. Furthermore historical definitions and the protective legislation based on them, have been rendered “obsolete” by anthropogenic environmental change. Thus interbreeding only means that the dingo today exists in a different form than its ancestors - some researchers now use the term evolving dingo. Protection for these dogs should be based on how and where they live, as well as on their cultural and ecological importance, instead of concentrating on precise definitions or concerns about genetic “purity”. This approach was generally agreed to, but also hinted that it would be difficult to prove that a species shapes its environment. Essentially the genetic integrity of the dingo is already lost due to interbreeding; however, the importance of this phenomenon is disputable according to Corbett and Daniels, since the genes come from a domesticated version of the same species.
This view point is rejected or at least controversially discussed by those who want to preserve the “pure” dingo. Here for instance the molecular biologist
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...
Alan Wilton from the University of New South Wales argues that a maximizing of the “genetic purity” is an essential aspect of the dingo conservation. Dingo-hybrids would supposedly increase the predation on native species, because they would have more litters per year and therefore would have to raise more pups and some of them would be bigger than the average dingo. He also argued that its for instance not sufficient to regard a wild dog with a little non-dingo-content as a “pure” dingo if it more or less acts the same way. Wilton was of the opinion that the scale had to be set higher and that you should not be satisfied with a replacement when “pure” dingoes are available. Corbett and Daniels agreed that it is practical and desirable to minimize the impact of other domestic dog genes. By this it would first be possible to find areas were the process is slower and to be able to limit it later; and second the populations would be able to develop accordingly to their natural environment
Natural environment
The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....
. Furthermore, hybrids and other feral domestic dogs would probably not have the same tourist effect, because they don’t correspond with the current expectations on wild dingoes.
To label this process, apart from the word interbreeding/hybridization, also terms like dilution of the dingoes or weakening of the genetic line are in usage. Even in the scientific area the process was called a sort of genetic pollution
Genetic pollution
Genetic pollution is a controversial term for uncontrolled gene flow into wild populations. This gene flow is undesirable according to some environmentalists and conservationists, including groups such as Greenpeace, TRAFFIC, and GeneWatch UK.-Usage:...
(itself a controversial term).
A demand for control of this process is based on the principle of caution and effective control measures are regarded as necessary. However this faces problems that are not negligible. To separate the “pure” dingo from other domestic dogs is difficult, if it is possible at all. The costs would be enormous, and even if you would want to kill all hybrids, there are currently no methods to tests the dingoes in the field. Furthermore, control measures usually do not discriminate between dingoes and other domestic dogs. According to the biologist David Jenkins from the Australian National University
Australian National University
The Australian National University is a teaching and research university located in the Australian capital, Canberra.As of 2009, the ANU employs 3,945 administrative staff who teach approximately 10,000 undergraduates, and 7,500 postgraduate students...
there is little that can be done to reverse the process of interbreeding. Even if you would go and kill every wild dog that does not look like a dingo, it would be of no use. And if you would selectively search for the dingo-hybrids during the killings, it would only disrupt the pack structure and therefore have an impact on the breeding rate of the dogs. For instance, if you kill the alpha-dog, the breeding-rate of the remaining dogs would increase.
Possible changes in behaviour and biology
The exact impact of domestic dogs from human households on the social structure of free living dogs in Australia is not well documented. However, it is regarded as likely that the same factors, that influence the social organization of dingoes in different areas also influence the social behaviour other feral domestic dogs and dingo-hybrids.The biology and ecology of dingo-hybrids has only been insufficiently researched, because most studies were limited on the topic of controlling these dogs. However, some changes in the wild dog population could be observed.
It is proven that there is a much wider range of fur colours, skull features and body sizes among the modern day wild dog population than in the times before the European colonization. Within Queensland for instance the different dog populations vary significantly, depending on the extent of interbreeding, while a bigger diversity of characteristics led to classification problems in Victoria and the term “wild dog” is now often used to label the current dog population. Evidence from south-eastern populations of Australian wild dogs indicates that the regular breeding rhythm of the dingo is interrupted, when a high number of dingo-hybrids and other domestic dogs, exists.
According to a five-year study of 2000 wild dogs from all states of Australia by Ricky Spencer from the University of Western Sydney
University of Western Sydney
The University of Western Sydney, also known as UWS, is a multi-campus university in the Greater Western region of Sydney, New South Wales, Australia...
some populations consist to 80% of dingo-hybrids and this enrichment of genes has provided a catalyst for the selection and micro-evolution
Microevolution
Microevolution is the changes in allele frequencies that occur over time within a population. This change is due to four different processes: mutation, selection , gene flow, and genetic drift....
of bigger wild dogs. Over the course of the last 40 years there was an increase of the average wild dog body mass of about 20%, with 40% of the adult wild dogs in the Southeast of the continent now weighing more than 17 kg. This larger dog size has led to a higher efficiency with which wild dogs kill major prey and models indicate that a pack of wild dogs today requires almost a quarter more daily energy intake than an average pack of wild dogs prior to 1980. Furthermore, due to the high number of kangaroos and livestock, the wild dogs have been given the necessary environment to reach larger sizes.
On the topic of possible changes in behaviour did Ricky Spencer commented that it is not predictable how the interbreeding will affect the behaviour of the dingoes; he assumed that there could be potential problems since supposedly only dingoes are not accustomed to humans. According to David Jenkins, the claims stating that hybrids are bigger, more aggressive and a risk to public safety have so far not been supported by data and personal experience. He mentioned that there are reports of one or two unusually big dogs captured each year, but that most hybrids are close to what's considered to be the normal weight range of dingoes. In addition, Jenkins has encountered wild dingoes and hybrids and reported that "there's something really going on in that hard-wired brain", but also that the dogs "tend to be curious, rather than aggressive."
Most attacks of wild dogs on livestock are supposedly caused by dingo-hybrids and not “pure” dingoes, however the impact of wild dogs on the cattle industry is very variable, generally low (0-10% losses per year) and the majority of the much more susceptible sheep industry is located in the areas south of the Dingo fence
Dingo Fence
The Dingo Fence or Dog Fence is a pest-exclusion fence that was built in Australia during the 1880s and finished in 1885, to keep dingoes out of the relatively fertile south-east part of the continent and protect the sheep flocks of southern Queensland. It is one of the longest structures in the...
, were the majority of the area has no stable wild dog populations and many of the remaining populations tend to have a high number of hybrids.
Ecological impact
Bush Rat
The bush rat is a small Australian nocturnal animal. It is an omnivore. It is one of the most common species of rats and is found in many heathland areas of Victoria and NSW...
s, where it is also seen as unlikely that there could be problems due to the dingo-hybrids, because these rodents had been exposed to the influence of the dingoes for thousands of years.
During studies on the efficacy of baits with 1080 (a deadly poison for canids
Canis
Canis is a genus containing 7 to 10 extant species, including dogs, wolves, coyotes, and jackals, and many extinct species.-Wolves, dogs and dingos:Wolves, dogs and dingos are subspecies of Canis lupus...
) in the Kosciuszko national park in the middle of the 1980s, the local dogs (which were not classified as dingoes) have been observed with home ranges of similar sizes like dingoes from Southeast-Australia. In addition these dogs also showed a preference for living prey, which lessened the efficacy of the baits. During studies in the Blue Mountains from March 2005 to April 2006 the main prey of the studied dogs consisted of Red-Necked Wallabies, Swamp Wallabies
Swamp Wallaby
The Swamp Wallaby is a small macropod marsupial of eastern Australia. This wallaby is also commonly known as the Black Wallaby, with other names including Black-tailed Wallaby, Fern Wallaby, Black Pademelon, Stinker , and Black Stinker...
, Grey Kangaroos, Common Wombat
Common Wombat
The common wombat , also known as the coarse-haired wombat or bare-nosed wombat, is a marsupial, one of three species of wombats and the only one in the genus Vombatus. The common wombat grows to an average of long and a weight of .- Taxonomy :The common wombat was first described by George Shaw...
s, Common Brushtail Possum
Common Brushtail Possum
The Common Brushtail Possum is a nocturnal, semi-arboreal marsupial of the family Phalangeridae, it is native to Australia, and the largest of the possums.Like most possums, the Common Brushtail is nocturnal...
s and European Rabbit
European Rabbit
The European Rabbit or Common Rabbit is a species of rabbit native to south west Europe and north west Africa . It has been widely introduced elsewhere often with devastating effects on local biodiversity...
s. The results indicated at a big hybrid-population that exerted significant pressure on Swamp Wallabies and controlled outbreaks of the rabbit-populations. According to David Jenkins, studies on wild dogs from the Kosciuszko National Park proofed that these dogs had about 75-80% content of dingo-genes and filled in the role of the apex-predator. Similar to “pure” dingoes, these hybrids hunted alone as well as in coordinated packs. The same ecological role was officially reported for the hybrids of the Namadgi-national park
Namadgi National Park
Namadgi National Park is located in the southwestern part of the Australian Capital Territory, bordering Kosciuszko National Park in New South Wales. It lies approximately 40 km southwest of Canberra, and makes up approximately 46% of the ACT's land area....
who filled the place of the apex-predator and kept kangaroo-numbers low.
Literature
- Lawrence K. Corbett: The Dingo in Australia and Asia. Cornell University Press, Ithaca, 1995, ISBN 0-8014-8264-X.
- Claudio Sillero-Zubiri, Michael Hoffmann and David W. Macdonald (editors): Canids: Foxes, Wolves, Jackals and Dogs. IUCN – The World Conservation Union, 2004
- Peter Fleming, Laurie Corbett, Robert Harden and Peter Thomson: Managing the Impacts of Dingoes and Other Wild Dogs. Bureau of Rural Sciences, Commonwealth of Australia, 2001