THE FLAWED AUSTRALIAN SAVANNAH STUDY
Copyright 2012, S Hartwell
This article analyses the comments made by the Invasive Animals Cooperative Research Centre (IA CRC) in response to the "Draft Environmental Assessment of the Suitability of the Import of the Savannah Cat (Domestic Cat X Serval Hybrid Specimens) Into Australia", issued under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) Part 13A on 19 June 2008. It also analyses "Pest animal risk assessment Hybrids of Leptailurus serval (serval) and Felis catus (domestic cat), including the ‘savannah cat’ (2009)" in Queensland, Australia.Introduction
Many of the references provided by the IA CRC were very recent and included a number of long-term studies. The studies reflected the state of knowledge about invasiveness at the time written. In the absence of additional data on impacts, the IA CRC felt it necessary to take a precautionary approach to the import of new hybrid species that were unknown entities.
The "Pest animal risk assessment Hybrids of Leptailurus serval (serval) and Felis catus (domestic cat), including the ‘savannah cat’ (2009)" (referred to as the "Queensland Pest animal risk assessment (Savannah)" for brevity) based its conclusions on the wild Serval and on early generation Savannahs that closely resemble the wild progenitor. However, cat breeders in Australia wished to import the F5 generation as this does not require CITES permits and is considered a domestic animal. The F5 Savannah, as defined by both CITES and The International Cat Association (TICA) is comparable to domestic cats in terms of size and behaviour. The Queensland study misunderstood the application of Filial generation numbers when backcrossing to a wildcat species. This renders a number of their conclusions unsound. The use of F1 to F5 generations is defined by both CITES and TICA and is shown diagrammatically in this report.
The IA CRC concurred with the Department of the Environment, Water, Heritage and the Arts (DEWHA) Draft Risk Assessment of the Suitability of the Import of the Savannah Cat into Australia, issued on 19 June 2008 that Savannah cats were unsuitable for import. They concluded that prohibiting import was the most cost-effective method of risk mitigation, to avoid potentially devastating consequences of the release of Savannah cats into the Australian environment. The reports believed that the genetic makeup of Savannah cats made it inappropriate for importation and that the Olsen and Jensz (2007) report was deficient in its analysis of the genetics of the F5 Savannah cats and media comment by potential importers of these animals in the past several weeks has indicated a lack of knowledge of animal genetics.
The IA CRC agreed with the DEWHA environmental assessment that Savannah cats represented an “extreme risk" to Australia’s environment. They supported the view that genes did not simply ‘dilute’ over generations of animals and that it was wrong to assert that F5 Savannah Cats had only 3.125% African Serval genes. The IA CRC and DEWHA have ignore breeding practices and the definition of the F5 generations and have ignored male sterility in the F1 to F4 generations that force breeders to outcross to domestic males.
The Australian argument included scare tactics i.e. the production of feral super-cats and used the Boolarra carp as a comparison study, but analysis of the spread of this invasive carp found the comparison to be flawed. Although hybridization between introduced plants is recognized as sometimes increasing invasiveness, this has not yet been confirmed in animals. In Helliconid butterflies, naturally occurring hybrids have proven more vulnerable to predation. The mixing of genes from multiple native sources of the same species may overcome the founder effect, producing genetic mixes and traits that may be suited to the introduced range. Natural selection in the new habitat will not necessarily favour those traits.
Although the Bengal (Asian Leopard cat hybrid breed) is already present in Australia, the same arguments and misconceptions are likely to be used in the future to prevent the importation of new Bengal breeding stock, other confirmed hybrid breeds and other breeds that superficially resemble wild species but which are wholly domestic (PixieBob). It may also impact the Toyger, a breed recently derived from the Bengal but with striped, rather than spotted, pattern.
According to the "Queensland Pest animal risk assessment (Savannah)" it is difficult to accurately predict the potential geographic distribution of the Savannah cat in Australia because it is a man-made hybrid. The report predicted its potential range as comparable to that of its progenitor species; the Serval and the domestic cat. The study correctly concluded that the Savannah would be suited to the same habitat types as feral domestic cats, but it suggested that the Savannah would still exhibit many of the Serval’s wild traits, such as size, agility and behaviour. This is true of early generation Savannahs, but the F5 Savannah (the generation breeders wished to import) is more comparable to the Oriental breeds of domestic cat, not to a pure Serval, in size, behaviour and physical ability.
Theories of Invasiveness
There are 3 general theories on invasiveness, all of which are applicable to Australia:
Phenotype and Genotype
According to the "Queensland Pest animal risk assessment (Savannah)" The common name "Savannah Cat" is a poorly defined marketing name used by a small number of professional cat breeders, generally applied to F5 hybrids of the African Serval and domestic cats. The report incorrectly states that such animals are also called "designer cats". The term "designer cat" is an umbrella term denoting any unregistered cross-breed with "mix and match characteristics" e.g. Sphynx x Munchkin cross-breeds.
"Savannah Cat" is not a marketing term, nor is it poorly defined. It is a recognised breed name with a breed standard registered with TICA. TICA define the Savannah as "a domestic breed which closely resembles its ancestral source, the African Serval, but is smaller in stature [...] with exceptionally long neck, legs, and tall ears" and note "The body on the Savannah is very long and the legs are quite long as well, creating a false image of a very large or heavy cat, but in reality, most Savannahs are just the size of a large domestic cat, and weigh less than another cat of similar size." TICA also state "Temperament must be unchallenging; any sign of definite challenge shall disqualify" which means that breeders must select for temperament as well as appearance. F5 and onwards (the generations Australian breeders wished to import) may be exhibited against this breed standard and are clearly defined in terms of size, conformation and temperament. The early generations are also properly defined; being prefixed F1, F2 etc by breeders in order to distinguish them from the exhibited Savannah.
The IA CRC wished to dispel the simplistic view that an F5 Savannah cat is only 3.125% African Serval. This is an average based on an F5 hybrid resulting from a simple halving of the Serval genes from 50% to 3.125% over 5 generations. This reduction would be seen only in the case where in each of the 4 generations of back-crossing, the hybrids chosen for mating to domestic cats were chosen at random without any regard to serval-like appearance.
They stated "almost all Savannah breeders market on the basis of the Savannah cat’s similarity to the African Serval. A Serval-like phenotype of breeding stock is therefore a paramount selection criterion. In other words, there is quite strong selection for serval appearance amongst the backcross hybrids, and inevitably this leads to the retention of a substantially higher proportion of serval genes at the F5 generation than expected with random selection. The stronger the selection for serval-like appearance amongst the backcross hybrids, the larger the proportion of serval genes that will be retained [...] It is seriously misleading to assert that F5 Savannah Cats have only 3.125% African Serval genes - the likely percentage is considerably higher due to phenotypic selection."
According to the "Queensland Pest animal risk assessment (Savannah)" the F (filial) number does not indicate the percentage of Serval genetic material contained within a particular animal and that it is not possible to scientifically measure the percentage of Serval genes in any given Savannah cat. While this is correct, the report erroneously states "Some breeders back-cross savannah cats with servals (as opposed to domestic cats) which results in later generation savannah cats (such as F5) having a higher ‘percentage’ of serval genes (Miller 2002)." Under both CITES rules and TICA Savannah breed development rules, a backcross of any F-generation Savannah to a Serval always results in F1 generation offspring; F1 denoting that one parent is a purebred Serval.
Backcrossing to domestic cats is necessary in Savannah breeding programmes because the first 3 - 4 generations of hybrid males are sterile. Even the most "wild looking" Savannahs have been diluted by 3 - 4 generations of breeding only with domestic cats (using breeds that maintain the overall look of the Savannah). Random assortment of genes means a mix of domestic and Serval genes are passed from generation to generation. Even if breeders select "typey" cats, the likelihood of F5 Savannahs retaining 50% Serval genes is remote.
Fertile males are produced at the F4 generation (more rarely at the F3 generation). Male fertility appears to be related to the percentage of domestic cat genes rising above a certain threshold. F4 males necessarily have a low percentage of wild genes due to several generations of backcrossing to domestic cats. Even if F5 males are used for mating to early generation females, the low percentage of wild genes in those males cannot seriously "upgrade" the next generation. Because the Serval genes are scattered through the chromosomes, it is unlikely that the males will pass on all of those Serval genes.
One American breeder planning to export to Australia boasted that her F5 Savannahs "look more like F3s". Apart from being advertising hyperbole (F3s are variable in type), this led the IA CRC to conclude that the F5s had substantially more than 3.125% Serval genes. The IA CRC claimed that, in theory, an F5 Savannah could be up to 50% Serval. In the absence of a genetic testing, the more an F5 animal looks like a Serval, the closer to 50% is its proportion of Serval genes likely to be.
This demonstrates ignorance of Savannah breed development under TICA rules. To get 50% Serval genes at the Fifth generation would require a backcross to a Savannah with a high percentage of Serval genes i.e. an earlier F-generation, or to the Serval itself. The resulting offspring would not be classed as F5. An F5 Savannahs is defined as 5 generations removed from the wild ancestor though repeated crossing to domestic cats. The exhibition Savannah commences at the F5 generation; earlier generations are registrable for use in breed development.
If the repeated backcrossing was to a Serval, the fifth generation would be approximately 96.8% Serval instead. Under CITES and TICA definitions the fifth generation are still F1 hybrids (albeit with a high percentage wild blood) because one parent is a pure Serval. After 5 generations crossing to domestic cats (bearing in mind male sterility in the early generations) the F5 generation would average 6% Serval genes.
There is no evidence that a female hybrid at any generation can selectively pass on all 50% of the Serval genes inherited from the initial hybridisation. It is unlikely in the extreme that this would happen in every backcross such that the F5 descendent retains the 50% of wild genes.
The IA CRC claims are fallacious. An F5 with 50% Serval genes is not possible because males with a high percentage of Serval genes have proven sterile, and backcrossing to an earlier generation or to a wild parent does not result in F5 offspring. F5 (five generations removed) are likely to have between 3% and 6% Serval genes, even allowing for genetic shuffling, because of the necessity to cross the F1 - F3 generation females to domestic males. The "50% scenario" is unrealistic and a scare tactic.
According to the "Queensland Pest animal risk assessment (Savannah)" "Since back-crossing of Savannah cats to servals is known to occur, it could be expected that fertility at F4 should increase and possibly even appear in F3 as it did in the Bengal cat breed." The fertility of the males appears to occur when the percentage of genes from one or other parental species rises above a certain threshold. Backcrossing of Savannahs to Servals could, therefore, result in fertile F3 males, but when these are bred to domestic cats their male offspring are likely to have infertility issues.
The IA CRC asserts that breeders can accelerate or decelerate the change in genetic composition by applying phenotypic selection during backcrossing. However breeders are restricted in their choice of backcross males by the problem of hybrid sterility. Genetic markers across the genome could theoretically be used to track the residual level of Serval genes in F5 cats (Marker Assisted Introgression). At the time of the reports, no Australian genetic laboratories had the capability to conduct such tests. So, the precise proportion of Serval genes in the Savannah cats proposed for import remains uncertain. They considered claims that F5 Savannahs were only 3.125% Serval to be contradicted by their appearance.
The IA CRC concluded that the 3.125% was over-simplified and based on a simple "divide by 2" formula. Genes are shuffled before being passed on and some offspring will inherit more Serval genes than others. However F1 to F3 males are sterile so F1 to F3 females must be bred to domestic cats, greatly reducing the Serval genes in the next generation. Only recently have fertile F4 Savannah males appeared (this being a young breed), having approximately 3% - 6% Serval genes due to 4 generations of backcrossing to domestic breeds.
Any claim that F5 generation Savannahs can have up to 50% Serval blood is unsubstantiated and is contradicted by TICA's registration rules. The F5 generation is, under cat registry definition, 5 generations REMOVED from the wild parent.
In the F5 Savannah population, the average percentage of Serval genes for that population would be 3.125% unless there is selective breeding from cats genetically identified as having higher or lower percentages. Due to natural variation, individual cats may have higher or lower percentages, but not the 50% claimed by the Queensland report or the IA CRC. The domestic outcrosses are chosen so that desirable traits (ear size, lithe conformation, colour and pattern) are maintained in the breed. Therefore physical appearance alone is not a guide to the percentage of Serval genes present. Feline geneticist Roy Robinson noted that "colour or size variations cannot be construed as evidence of hybridity".
In order to maintain an average of 3.125% African Serval genes, the F5 Savannahs must be bred among themselves with no outcrosses to other domestic breeds. If an F5 Savannah is allowed to breed with other domestics, the Serval genes in its offspring will be reduced. Each succeeding generation that is outcrossed to other domestic cats will see a reduction in Serval genes. There is no evidence that Savannahs will, of their own accord, select only other Savannahs to mate with or that F5 Savannah males will out-compete other males when fighting for mating rights.
In a free-breeding situation, generations of crossing to the more numerous feral domestics will virtually eliminate the influence of the Serval genes due to them being "swamped out". Unless an escaped hybrid finds its way into a small, isolated domestic cat population and its progeny are fully fertile, fears of a self-perpetuating strain of notably large hybrids are very wide of the mark. For example, Waipiti have been introduced into Red Deer herds to improve Red Deer type (for hunting trophies). The Red Deer type degenerated and the introduced "improving" genes were swamped out. Savannahs and other hybrids must be selectively bred using the best specimens from each generation (this does not necessarily mean the highest percentage of wild blood, it means "closest to the breed standard") fixing these traits in the population by preventing free breeding. Left alone, nature breeds out the influence of introduced individuals (who are usually in a minority) until the norm is restored. As Roy Robinson noted, over the succeeding generations there will be a selective return to the original genetic combination prevalent in the area (unless there is selective pressure that favours the "new" type genes).
The IA CRC felt that the very dilute amount of Serval genes from the F5 Savannah entering the Australian feral cat population could confer a fitness benefit that would be highly selected and/or result in hybrid vigour. New genes can ‘supercharge’ a feral population through hybrid vigour and/or by generating advantageous phenotypes outside the previous range. However their conclusions appear based on the phenotype of early generation hybrids rather than on the F5 and later generations. They considered proposed confinement procedures to be unenforceable over the longer term with these animals in private homes. Studies in Helliconid butterflies and in Mule Deer/White-tailed Deer hybrids found the hybrid phenotypes to be at greater risk of predation.
The IA CRC considered it fanciful to assert that the African Serval’s genes would be diluted and have no effect in a feral population. Although it admitted the outcome is not a certainty, it believed that those genes would be favoured rather than diluted. This contradicts evidence in wild situations involving mammals. In Wapiti/Red Deer hybrids the "superior" conformation of the introduced animals was quickly lost. In natural Mule Deer/White Tailed Deer hybrids, they were at greater risk of predation. Beneficial phenotype changes might occur if individuals with the highest percentage of Serval genes (from genetic shuffling) always bred with each other. While this might fix certain traits it would not reintroduce Serval traits that had been bred out during the F1 to F4 generations.
Even if the Savannah males got first mating rights with females, the offspring are frequently fathered by subsequent mates. Unlike the fish and dingoes used in the IA CRC's comparison, cats are induced ovulators. Females ovulate AFTER mating. The first mating would cause her to ovulate. She then needs to mate several times with the same male for him to fertilise the eggs. Unless she remains with the same male for subsequent matings, most of her mates are likely to be the more prevalent moggies, limiting the number of "hybrid" offspring produced.
Should a Savannah enter the feral cat population and breed, the introduced genes would become diluted with each succeeding generation unless selective breeding occurred. Where there is already a stable "type" adapted to its environment, natural selection acts to preserve or restore that type. Domestic cats are adapted to hunting small mammals and birds and there is no evidence that a change of phenotype would be advantageous to free-breeding feral cats in Australia unless that change is driven by, or supported by, changes to the cats' environment or to the type of prey available.
According to the "Queensland Pest animal risk assessment (Savannah)" the major concern is the potential for genetic material from the Savannah hybrid (and therefore from the wild Serval) to enter the existing feral cat population in Australia. Given the size and agility of the wild serval and the Savannah (the report bases this on the large early generation hybrids, not on the F5 generation), it seemed reasonable to the report's compilers to expect that cross-breeding with feral domestic cats could result in considerably larger feral cats. In addition, they believed the high kill-rate of the wild Serval (almost 50% of hunts being successful) (Geertsema 1985), in comparison to feral cats (only 10%), that such cross-breeding could result in increased hunting efficiency within the feral cat population, exacerbating the threat to Australia's small to medium sized mammals.
According to the "Queensland Pest animal risk assessment (Savannah)" "Savannah cats are approximately twice the weight of feral cats in Australia and so have the potential to take prey similar to the size taken by foxes in southern Australia." This applies only to early generation Savannahs, not the show quality (F5 onwards) Savannah that Australian breeders wished to import. The TICA breed standard states "The body on the Savannah is very long and the legs are quite long as well, creating a false image of a very large or heavy cat, but in reality, most Savannahs are just the size of a large domestic cat, and weigh less than another cat of similar size."
The "Queensland Pest animal risk assessment (Savannah)" report admits that its predictions are speculative and based on the wild Serval, there being no available published information on impacts of the new Savannah breed. This raises the question whether there should be specific impact assessments on two large, heavy cat breeds already present in Australia: the Ragdoll and the Maine Coon. If a cat's weight is used as a measure of superior hunting ability, obese domestic cats also present an increased danger to medium sized mammals.
While an "escaped, dumped or promiscuous" F5 Savannah could pass Serval genes onto a population are those genes sufficient to convey a degree of fitness over the general population such that they are selected in future generations? The Serval’s efficiency as a hunter is partially attributed to its superior hearing in the ultrasonic range. This does not mean that a cat 5 generations removed from the wild Serval inherits this trait. Part of the Serval's superior hearing ability is due to ears that are large in relation to body size. The F5 Savannah's ears are comparable in size to those of the rather "bat-eared" modern Siamese cat already bred in Australia (but are set closer together on the top of the head). While owners report they are unable to surprise their pet Savannahs, this is not necessarily an indicator of superior hearing inherited from a wild ancestor, but of alertness in individual cats, and can be found in other pure-bred and random-bred cats. The IA CRC claims Savannah cats are renowned for their ability to jump much higher than domestic cats and that this would be quickly selected for in a feral population, conveying superior hunting skills. Earlier generation Savannahs are larger and able to jump much higher; while "leggy" the much smaller F5 Savannahs have agility and athleticism comparable to Siamese/Oriental breeds.
Unless large numbers of large, fertile F4 males were released into a feral population where they out-competed existing feral domestic males and impregnated large numbers of females, any exotic genes would be very dilute within the feral population. Those genes may not confer any advantage over the existing feral cats that have adapted over many generations to the Australian environment. Reports dwell on the legginess and large ear size of Savannahs, but those attributes are already found in Oriental/Siamese breeds of domestic cat. The purported large size is not consistent with the TICA breed standard that applies to F5 Savannahs.
Breed Foundation Cat Welfare
"Savannah cats are derived from unsound animal welfare practices which are at odds with the Australian Animal Welfare Strategy, endorsed by all Australian governments."
With all breeds of cats and dogs there are rogue breeders who put profit above animal welfare. It is believed there are rogue breeders who put "any available female" with a male Serval that is not sufficiently imprinted on domestic cats and who hope that some of the females survive the experience and become pregnant. These breeders aim to mass-produce hybrids as pets and are no different from kitten farms. Their "product" is not produced with a breed standard in mind and is rarely registerable with a cat registry. The tighter controls on ownership of exotic animals has thus far prevented this scenario in the UK. Because the proposal was to import F5 Savannahs, the creation of F1 hybrids in other countries is beyond the scope of the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), but the IA CRC believed the derivation of the Savannah breed to be contrary to the Australian Animal Welfare Strategy (AAWS), which is endorsed by all Australian Governments. The AAWS vision is that the welfare of all animals in Australia is promoted and protected by the development and adoption of sound animal welfare standards and practices.
The IA CRC considers that mating an African Serval with a domestic cat is not a sound animal welfare practice. The TICA Breed Standard for the Savannah cat allows the creation of new foundation lines and permits outcrosses to the Serval. While TICA allows crossing back to Servals (which produces F1 hybrids), it does not mandate it. The TICA practice does not mean that Australian breeders must also follow this practice. Because Servals are not kept as pets in Australia, such practices could not occur.
The crux of their welfare argument is that the species have gestation periods that differ by 10 days. Because F1 Savannahs are the result of a male Serval to female domestic cat mating, the kittens may be miscarried, stillborn or premature (by Serval standards), requiring intensive post-natal attention for survival. IA CRC states that "Savannah cat websites often describe the birth and survival of Serval-cat offspring as a ’miracle‘ because of its rarity. We suggest that it is entirely predictable that mating animals with significantly differing gestation periods will result in poor welfare outcomes and therefore should not be practised."
Other Savannah breeders have experienced none of the reported issues and the kittens have been born full-term and reared by their own mothers. The report fails to recognize the fact that gestational differences do not invariably result in problems because there is some natural variation in the domestic cat's gestation period. This conclusion is a red herring because Australian breeders sought to import existing Savannah hybrids which do not experience any of the gestation differences reported in some Serval/domestic matings.
It should be noted that the Savannah originated from an unintended mating between a pet male Serval and a domestic cat female and that live offspring resulted. Savannah cat websites may also overstate the "miraculous" nature of kitten survival to enhance the image of rarity (and therefore its desirability).
"Much has been made in the media of the fact that TICA registers the Savannah breed. It is our understanding that the three other large international registries expressly exclude the possibility of registering this breed, or any other derived from wild-domestic matings"
TICA is a worldwide registry that defines what a Savannah is and provides a sound methodology for breed development and advancement. TICA reiterate that an F5 Savannah is 5 generations removed from the wild species ancestor, and that backcrossing an F4 Savannah to an earlier generation (F1, F2 or F3) does not result in F5 offspring. By allowing hybrids to be developed under TICA auspices, it makes breeders less likely to use "paper registries" (that do not have committees, shows or affiliated breed clubs) that may recognise anything and everything with the risk of legitimising back-yard breeders.
Each cat registry sets its own policies. The Cat Fanciers Association (USA) policy on the breeding of domestic and non-domestic cats was set on February 7-8, 1998 by unanimous approval from their board of directors. The board reconfirmed that the CFA is a registry of Felis catus species of domestic cats and therefore does not accept hybrid breeds: "The Cat Fanciers' Association, Inc., does not encourage or promote the breeding of non-domestic (wild) cats of any species to any domesticated cats. Furthermore, The Cat Fanciers' Association, Inc. will not consider for registration the offspring of such a breeding. "
The France-based Fédération International Féline (FIFe) recognised the Bengal breed but does not intend to recognise further hybrid breeds. The situation in continental Europe is further complicated by European companion animal legislation; it imposes restrictions that override registry policies.
The Governing Council of the Cat Fancy (GCCF - UK) recognised the Bengal breed but decided further breeds derived from wild cats would not be considered for registration. It should be noted that the GCCF polices remain rooted in the late 19th Century and deficiencies were highlighted in the 1990s when the GCCF's lacked a mechanism to recognise anything other than new colour mutations within established breeds (e.g. it cannot recognise a spontaneous rex mutation in an existing breed). The GCCF's shortcomings causes an increasing number of British breeders to look for more progressive and flexible registries or to register their cats with TICA. The Savannah and the Toyger (a Bengal derivative)and other hybrid breeds have been accepted into Britain, regardless of GCCF sensibilities.
The Savannah (as defined in the breed standard) is not a currently recognised breed with either of Australia's cat registries (the Co-ordinating Cat Council of Australia (CCCA) or the Australian Cat Federation Inc. (ACF)) or with their affiliated associations in Australian states. However, if the breeding of Savannahs becomes established in Australia, the major associations will probably recognise the Savannah breed, as they have previously done for Bengal hybrids.
The "Queensland Pest animal risk assessment (Savannah)" erroneously asserts that "[recognised] Breeds developed from the serval include spotted-tabby oriental shorthair, Egyptian Mau and the Ocicat. All these breeds have a spotted coat. Identification on morphological grounds may be problematic." No other breeds have been developed from the Serval (the putative Ashera breed was a rebadged Savannah). The Oriental Shorthair, Egyptian Mau and Ocicat are all wholly domestic breeds. The Oriental Shorthair is the crossing the Abyssinian and Siamese. Claims that the Egyptian Mau resulted from Serval hybrids in the Pharaonic Age are anecdotal. These spotted breeds have previously been used as outcrosses when developing the Savannah.
Heritage Value of Domestic Animals
"As a new breed only established in the last two decades, there is no heritage value of Savannah cats. It is extremely unlikely any immigrants to Australia have left behind a valued pet from this breed. Denying ownership of a Savannah cat to any Australian is of insignificant consequence."
There is no heritage value in most of the cat breeds now perpetuated in Australia. This argument is inconsistent. Equally, recently developed home-grown breeds equally have no heritage value. However, immigration into Australia is ongoing and recent immigrants to Australia may be forced to leave behind a valued Savannah cat pet.
"The benefit of Savannah cats to Australia is exceptionally small and cannot justify the risk involved. Consequently, the Invasive Animals Cooperative Research Centre strongly opposes the importation of Savannah cats into Australia."
It should be noted that, in environmental terms, there is no benefit in importing any new breeds of any non-native species into Australia (including breeds of livestock). It is a decision that can be swayed by economic benefits of the animal to humans, in which case the impact on the environment will almost certainly take second place. For example native kangaroos are culled in areas where large populations compete for grazing with economically more valuable introduced sheep.
Domestic cats are listed under the Environment Protection and Biodiversity Conservation Act 1999 Section 303 EB(1) as ‘Specimens Taken to be Suitable for Live Import Part 1’, which is the list of animals that do not require an import permit. However, this excludes any specimen of Felis catus derived from cross-breeding with: (a) a Felis serval or (b) a savannah cat (Felis catus × Felis serval). In Queensland, servals and their hybrids have pre-emptively been declared pests under the Queensland Land Protection (Pest and Stock Route Management) Act 2002 and cannot be kept without a permit. Permits are not available for animals kept as pets.
Desirability of Creating Hybrids
The desirability of creating hybrids is a matter of debate. The Serval stock from which the Savannahs are derived were captive-bred for the pet trade and not taken from the wild. Pet trade Servals are mongrelised and do not belong to any single subspecies, therefore have little conservation value. It is arguable that no exotic animals, including wild cat species, should be kept as pets or in private menageries.
Felids exhibit a trait called hypersexuality. If there is no mate available of their own species, they will mate with a closely related species resulting in sterile males and fertile females. In captivity, wild cats species that were raised or housed together have produced unplanned hybrid offspring, often to the surprise of the keepers. This includes serval/caracal hybrids (at a zoo), jaguar/lion hybrids (at a rescue facility) and ocelot/puma hybrids (in a private menagerie). These selected examples were all accidental. The original Savannah cat also resulted from an accidental mating where a pet male Serval was kept in a home that also had domestic cats. The same has occurred where a male Oncilla and a male Ocelot were kept in the home alongside domestic cats, in each case resulting in unplanned hybrid offspring. The hybrids were not "created" in that the mating of two species was not engineered by the keepers.
Hybridisation is surprisingly widespread in the wild where it may have a survival benefit as the fertile females ensure valuable genes are preserved. The fertile female hybrids may naturally breed with a male of either parental species. Some species have "overlap" zones where hybrids occur. Oncillas and Geoffroy's Cats may hybridise in parts of southern Brazil where their territories overlap. Lynxes and bobcats have also formed natural hybrids. All of the F silvestris wildcats can interbreed and also hybridise naturally with the domestic cat (which is a domestic form of F silvestris lybica). Free-ranging domestic cats also form natural hybrids with several wild species including the Rusty-Spotted cat (Prionailurus rubiginosus, around Indian villages), the Jungle Cat (F chaus) and Caracal (Caracal caracal, in Moscow Zoo). The domestic x Caracal hybrid (apparently resulting from a feral cat infiltrating the caracal enclosure) is comparable to domestic x Serval breeding in terms of size and gestation differences.
Exotic-looking hybrid pet cats allow people to own a wild-looking spotted domestic cat as a safe alternative to owning a potentially dangerous wild species that requires specialist knowledge and housing. This also reduces the demand for the wild species for the pet trade where they may not thrive. While some humans may consider the creation of hybrids undesirable, nature has no such scruples.
Anti-Hybrid Propaganda from the USA
A great deal of misinformation about domestic hybrid cat breeds, including the Savannah, has been disseminated by the US organisation Big Cat Rescue (BCR) to support their anti-hybrid agenda. Their status as a Rescue means that their erroneous claims have been repeated as fact.
BCR erroneously labels the Savannah and other recognised hybrid breeds (e.g. Bengal, Chausie) as "exotics” alongside lions, tigers and big cat hybrids. This conflicts with US federal law, which defines F1 hybrids as "domestic" not "exotic". It should be noted that US local laws vary; wild/domestic small cat hybrids are considered "domestic pets" at either F1, F2, F3, F4 or F5 generations depending on state/county/municipality legislation. Some states prohibit private ownership of hybrids entirely, or selectively prohibit certain breeds and/or generations. Outside of the USA, restrictions on owning and housing of earlier generation hybrids vary according to country and wildcat species involved
Savannahs are bred for a “wild” look, using selected domestic breeds to perpetuate the large ears, long legs and black spots into later generations. Their "wild" appearance often misleads people into assuming their temperament and/or behaviour is also wild. BCR do not understand that appearance is deceptive (or are inept at interpreting small cat behaviour). Regardless of their appearance, the Savannah behaves like any other high-energy, interactive domestic cat. They are comparable to Abyssinians and Orientals in wanting to interact with their owners and being toy-oriented. Any domestic cat will scratch or bite if frightened or aggravated, but there are no documented cases of Savannahs attacking their owners, small children, pet dogs or other domestic cats. Despite this, fallacious claims that Savannahs will attack small children, little old ladies and domestic dogs (including large dogs) have been repeated verbatim on Australian blogs and websites opposed to the Savannah. The Bengal breed was previously subject to similar false allegations .
BCR assert that Savannah cats belong in a cage, not in the home. They claim the cats are essentially wild in nature and unsuitable as pets, requiring raw meat diets and wild cat habitats. Purebred and random-bred cats with no hybrid ancestry also enjoy raw meat diets and wild cat habitats and this is not in itself an indicator of "wildness" or "non-domesticity".
As part of their anti-hybrid stance, BCR have a YouTube video showing an F1 Savannah cat “rescued” from a wildlife sanctuary that didn’t know what to do with it. Because the cat appeared happy living in an enclosure eating raw meat and whole prey, this was used to prove that it was wild and should be treated the same way as captive wild species. In the USA, large numbers of cat (and dog) owners feed their domestic pets a supplemented raw meat diet in preference to feeding commercial cat foods that contain large quantities of cereals and additives. This is called the "raw diet revolution" and includes the "BARF - Bones And Raw Food" diet and is gaining popularity around the world. In Australia, some veterinarians advise the feeding of raw bones and raw chicken wings to improve dental health of pet cats - supposed wildness of the cat not being a factor.
Due to the prevailing culture of keeping cats as "indoor only" pets in the USA, BCR appear to forget that most domestic cats enjoy outdoor access and that cats are indoor/outdoor pets in most countries. Domestic cats unable to have unrestricted outdoor access, from pedigree Persians and show-ring Siamese to rescued randombreds, may also enjoy outside enclosures. Indeed, large outdoor pens are provided by many domestic cat owners in countries such as Australia and South Africa where free access to outdoors is unsafe for either the cat or the local wildlife. Many cat shelters around the world also provide outdoor enclosures to enrich the lives of wholly domestic cats in their care.
BCR's anti-hybrid propaganda points to the few US states and counties that restrict or ban the ownership of domestic/wildcat hybrid breeds. In most of those cases, the aim of the legislation is to ban "exotics" “and hybrids thereof”; the phrase "hybrids thereof" being intended to close a loophole that made it legal to own big cat hybrids (ligers, tigons) in states or counties that banned private ownership of lions and tigers. In cases where hybrid breeds, or certain generations of hybrid breeds, are banned or restricted, it is usually due to misconceptions of what a hybrid cat is like. Most legislators would not have researched the hybrid breeds themselves, or met one in the flesh at a cat show or breeder's home, but would have relied on seemingly plausible reports from biased sources that misrepresent hybrids.
BCR calls domestic hybrid breeds such as Savannahs, Bengals and Chausies “unnatural” in that they don’t occur in the wild and therefore should not be bred. The modern Persian cat is equally unnatural, having been produced through selective breeding. It is also false that wild/domestic hybrids do not occur in the wild. Free-ranging domestic cats have hybridised with several wild species including the Jungle Cat (F chaus - used in developing the Chausie) and even the much larger Caracal, the latter apparently being due to a feral cat infiltrating the caracal enclosure at Moscow Zoo. Anecdotally, domestic cats have naturally bred with Asian Leopard cats (resulting in the Ussuri in Russia). There is speculation that Servals may have bred with female domestic cats when both species were kept as pets and rodent controllers in ancient Egypt. Some believe that the Egyptian Mau (possibly the oldest domestic cat breed) originated from a Serval-domestic cross. Although DNA evidence is lacking, a naturally occurring hybrid is not impossible: the modern Savannah originated from a male Serval that was raised among female domestic cats and later mated with a Siamese cat, producing viable kittens.
Most people are attracted to spotted wild cats, but owning such a cat, even one of the smaller species such as the Ocelot or Margay, is a huge responsibility and requires specialist knowledge and facilities. In contrast, hybrid domestic breeds provide the opportunity to own a cat that resembles its wild ancestor, but behaves like a domestic cat and presents no danger to humans, dogs or other cats in the household. This makes it less likely that wildcat kittens end up in the hands of people who find themselves unable to cope when it reaches adulthood. Owning a hybrid breed instead of a wild species reduces the number of wildcats relinquished to wild animal rescue organisations. This may contribute to BCR's opposition to hybrids - without relinquished or confiscated wild species, there would be less need for BCR. Opposing hybrid domestic breeds also gives them a wider audience (the general cat lover/cat fancier) and opportunities to publicise their facility in mainstream, rather than niche, media.
BCR erroneously claim that hybrid domestic cat breeding is wrong, because all first-generation hybrids are wild and uncontrollable and hence end up in a Rescue. According to Savannah Rescue, those that are relinquished by their owners are mostly F3 and F4 Savannahs and are surrendered for exactly the same reasons as any other domestic cat: family members developing allergies; moving to a "no-pets" apartment; new partner hates cats; old wives' tales that the cat will smother the new baby; moving to an area where hybrids are restricted/banned. As with rescued cats of any breed, a rescued Savannah may be traumatised or even poorly socialised, but this is a result of its individual circumstances and is not an indication the Savannah breed is intrinsically wild, dangerous or vicious. The author of this article has come across feral Burmese and feral Persians resulting from lack of early socialisation/poor ownership.
Unfortunately, the misinformation from BCR's has been widely reproduced and is used to underpin opposition to the Savannah, despite the body of evidence to the contrary available from Savannah owners.
Who Defines the Point at Which a Hybrid Breed is "Domestic"
The Servals used in Savannah breeding are not a single subspecies, but are mongrels originating from the pet trade, not from the wild. Under the Convention on International Trade in Endangered Species (CITES), international trade in Servals and Serval products (including hybrids) is "controlled", not "prohibited".
"The CITES definition of an animal hybrid is used correctly in DEWHA’s Risk Assessment to determine that F5 Savannah Cats fall outside that convention. However, it has been incorrectly applied elsewhere to argue that an F5 Savannah Cat is domestic. It is important to note that the Convention on International Trade in Endangered Species (CITES) does not define what constitutes a domestic animal. The hybrid definition (attached as Appendix 3 of the Draft Risk Assessment) is merely to determine coverage of the Convention. DEWHA’s assessment correctly deals with this matter. However, Olsen and Jensz (2007) state that ‘…the United Kingdom applied the F5 CITES requirements in regards to the import of wild cats or their hybrids, that is, fifth generation hybrids were considered to be domestic’."
"We strongly disagree that the CITES hybrid definition - intended to stop international trade in endangered species - should be used to determine in any way which animals can be freely traded and privately owned in Australia. Even if the United Kingdom uses the definition for importation purposes into that nation, it does not follow that this use is appropriate for Australia, with our unique fauna and flora."
"DEWHA’s draft assessment uses the CITES definition simply to determine the status of an F5 or later Savannah cat under the convention, in line with the Terms of Reference provided under Part 13A of the EPBC Act. Unfortunately, it is clear from media statements by Savannah cat importers and the Pet Industry Association of Australia that an expectation has been built that the F5 somehow represents the point at which these animals can be regarded as domestic and therefore ‘safe’."
Under CITES, the F5 generation can be traded without import or expert permits. By this stage - 3-4 generations of outcrossing to domestic cat males - the percentage of domestic cat genes becomes so high and that of Serval genes so low that there is no good reason to consider the cats anything other than wholly domestic. The IA CRC scenario of F5 Savannahs with a high proportion of Serval genes is unrealistic because of lack of fertile hybrid males in the F1-F3 generations. Backcrossing to an earlier generation (e.g. F4 male to F2 female) increments the lowest F-number, not the highest F-number (F4 x F2 gives F3 offspring, not F5 offspring).
As a comparison, the long-established Bengal, derived from hybrids between Asian Leopard Cats and domestics, has been found to be wholly domestic at the F5 generation. That breed was also subject to scare stories and hype about their purported "wildness". Despite sensationalist stories by journalists, F5 Bengals proved comparable in size, behaviour, activity level and temperament to other "active" breeds such as the Burmese, Tonkinese, Siamese and other cats in the Oriental/Foreign category.
The "Queensland Pest animal risk assessment (Savannah)" notes that Savannahs are very active and can leap 2.5 m high from a standing position. It does not note that Oriental/Siamese cats can be similarly active, agile and athletic. The risk assessment states "Wild-type behaviour can be observed in early generation or non-socialised Savannah cats. For example, they may hiss and growl at strangers. They also make noises similar to a serval, such as chirping and loud hissing" but omits the fact that Australian breeders wished to import F5 or later generations, making this observation inapplicable. The reference to "non-socialised Savannah cats" is applicable to the early generations, non-socialised later generations behave as non-socialised domestic cats.
"Driscoll (2007) indicates that cats were domesticated between 12,000 and 8,000 years ago. The process appears to have been that cats chose to associate with humans as humans established permanent homes, rather than through humans capturing wild cats. We know that even with a history of thousands of generations as a domestic animal, cats can revert to wild living very successfully. In the absence of any scientific literature in regard to the Savannah cat, we believe it is entirely inappropriate to assume that five generations represents some magical point at which domesticity is reached. The precautionary principle would point us in quite the opposite direction."
An F5 Savannah means that both parents are Savannahs. In the F1 to F3 generations, Savannah females are, of necessity, crossed to domestic cat males, progressively reducing the percentage of wild genes in each generation. By the F5 generation, the low residual percentage of Serval genes in an F5 Savannah is insufficient to undo 8,000+ years of domestication.
The IA CRC needs to remember that domestic cats are a subspecies of Felis silvestis lybica and are genetically almost identical to the parental species. Domesticity in the pet cat is based on temperament and behaviour, not purely on genetic composition. Feral cats are wild in nature, yet are genetically identical to domestic cats. "Domestic is as domestic does" - a cat with wholly domestic genes can be entirely wild, while a cat with a very low percentage of genes can be entirely domestic.
Flawed Comparison of Savannah With Invasive Boolarra Carp
"New genes can ‘supercharge’ feral populations. There are numerous examples where new genetic lines have led to feral populations taking off, most likely through hybrid vigour and/or by generating advantageous phenotypes outside the previous range."
Carp occupy a wide range of habitats, ranging from freshwater to slightly brackish and a temperature range of 23 - 30 Centigrade. They tolerate low oxygen levels and have a wide-ranging diet, preferring bottom-feeding in sediment. They are held responsible for permanent turbidity and loss of submergent vegetation in the Murray–Darling Basin, creating a habitat detrimental to native species, but conducive to carp. They are also well-adapted to survive in habitats that are altered or destroyed by salinity changes, water level fluctuations and changes in water catchment areas; all of which occur naturally or through human activity. In Australia they spawn between September and December at temperatures of 17-25 Centigrade and one female can produce over a million eggs in the breeding season (typically 300,000 eggs per spawning). They are heavily predated by carnivorous fish and by piscivorous birds, reptiles and mammals. There is high mortality of eggs and fry.
Studies showed that under certain conditions carp may be detrimental to the aquatic environment. Investigation found them to be a pest when they occur in ecologically, recreational or economically valuable bodies of water in densities greater than 450 kg of carp per hectare of water. Below this density, they are deemed unlikely to cause appreciable damage to the environment. Carp are now considered permanent residents in Victorian waters and treated as a resource and an occasional pest.
"Haynes (2008) has studied the genetic make-up of populations of common carp (Cyprinus carpio). Within the same species, different strains of carp have had significantly different invasive impacts in eastern Australia. Common carp were introduced in the 1860s as an aquaculture species, and the ‘Prospect’ strain, as it became known, had little impact on the environment. However, the ‘Boolarra’ strain of carp, introduced in the 1960s, became a highly invasive species, spreading throughout most of the Murray–Darling Basin. There is no doubt that environmental factors assisted in the spread of the Boolarra strain. Nevertheless, this example shows that very small differences in genetic composition (between strains) can be associated with substantially different invasive impacts. "
Two different strains of carp (Cyprinus carpio) were introduced to south-eastern Australia in the mid to late 1800s but were not a problem until a fish farmer released a particularly robust strain in the town of Boolarra, in Victoria, in the early 1960s. DNA studies show the Boolarra strain is genetically closest to German carp populations and was pre-adapted to its new environment. It did not need to breed with the Asian strains of carp to do well therefore it did not "supercharge" local populations; rather it was released into the environment in such large numbers it was able to absorb or out-compete earlier populations.
In 1978 K.D. Shearer and J. Mulley identified three distinct strains of carp in Australia: the "Prospect" strain introduced into Prospect Reservoir in the late 1800s; the "Singapore" strain (feral Koi carp) introduced into the Murrumbidgee Irrigation Area and "River" or "Boolarra" strain released into the Murray drainage basin in the 1960s. Unlike the proposed importation (and possible escape) of Savannah cats, the Boolarra carp were bred and released in huge numbers, swamping out the earlier less invasive strains previously introduced.
In Victoria, the Fisheries Act of 1958 prohibited stocking of non-indigenous fish in public waters but did not prohibit this in private waters. In 1960, a fish farmer applied to the Fisheries and Wildlife Department to import Carp from Germany to stock breeding ponds in Gippsland. In July 1960 he offered "a fast growing and hardy fish suitable for stocking in a majority of dams and ponds" for sale. In May 1961 he offered Cyprinus carpio for sale in quantities of 1,000 or more that could be delivered anywhere in Victoria or the Riverina. By June 1961, large numbers of these carp had been liberated in farm dams in many parts of Victoria. In December 1961, sale of these carp in Victoria was prohibited, but the robust Boolarra carp had become established in large numbers in farm dams into Victoria's river systems. Not until May 1962 were they declared a "noxious fish" and the Fisheries and Wildlife Dept were empowered to enter private property to eradicate them from 1300 farm dams before the September-October breeding season. In March 1963, they were found at the Yallourn Storage Dam on the Latrobe River (south-east of Victoria); they survived poisoning and bred. By February 1965 they had repopulated the dam and escaped into the river downstream. In addition, carp had been illegally and secretly stocked elsewhere in the Latrobe Valley without the owners' permission. Around September 1967, the carp were found near Mildura in the brackish Lake Hawthorn connected to the Murray River and in the Murray River itself (far north-west of Victoria). Their size meant they had been introduced there some years earlier.
Having been deliberately stocked in lakes and farm dams in large numbers, the carp bred successfully and were able to colonise the whole region. They did not "supercharge" an existing feral population, but were stocked and escaped/released in large numbers (multiples of 1000 fish) and reproduced in large numbers (300,000 eggs in a single spawning; 2-3 spawnings per season) so that eradication efforts could not be sustained. Their large numbers absorbed the existing populations. This is a very different scenario to the Savannah cat where the small number would be absorbed by existing populations.
"Hänfling (2007) reviewed the important role that hybridisation plays in making an introduced species invasive. Hybrid vigour, or heterosis, may occur and confer a benefit on the progeny. Also, novel allele combinations may improve the potential for survival and reproduction in a new environment, by extending the phenotypic range of offspring beyond that of the parents (for example, producing a better camouflage coat). "
New genes can only supercharge feral populations where the environment favours the new genes over the existing genetic makeup. In the case of the Boolarra carp, it was a numbers game rather than a "hybrid vigour" game. The fish strain imported from Germany was selected to be robust and to breed well. The F5 Savannah cat is no more or less robust than other cat breeds and it does not breed more often, or with larger litters, than other cat breeds. Outside of urban areas (where cats primarily scavenge rather than hunt), the predominant colour/pattern of Australian feral cat appears to be a broken-striped grey/brown tabby (produced by natural selection), therefore the spotted Savannah does not have more advantageous camouflage.
Fish release large numbers of eggs and milt, producing more offspring and with greater potential for hybridization at spawning sites due to external fertilization. Cats are unlikely to raise more than 3 litters per year, averaging 4 offspring per litter. Among feral cats the mortality rate is as high as 80%. F1 to F4 generations of Savannah males are sterile which limits the spread of wild genes. The hybrid females can only reproduce if they mate with non-hybrids i.e. domestic cats (there being little likelihood of a Serval loose in Australia) which dilutes the genes. By the time fertile males appear in the F5 generation (rarely in F4), they will carry very few serval genes.
Advantageous mutations can occur within existing feral populations. There is currently a scare over "giant ferals" (comparable to "blank panther" sightings in Britain), particularly in Gippsland. Because of the very low percentage of novel genes in a Savannah (these being primarily colour and pattern genes, other wild traits being selectively bred out), the Savannah is extremely unlikely to have any greater impact than a local mutation.
Comparison of Savannah With Dingoes
"New genes can ‘supercharge’ feral populations. There are numerous examples where new genetic lines have led to feral populations taking off, most likely through hybrid vigour and/or by generating advantageous phenotypes outside the previous range."
"Data from Australian wild dog populations support the view that divergent lines of animals coming together in a feral population may make the population more invasive (Spencer et al unpublished). Prior to the 1970s, wild dogs in southern Australia weighed an average of 14.5 kilograms. They are now an average 17.5 kilograms and, particularly in the Great Dividing Range, we are seeing what these authors describe as ‘super-dingoes’. These data imply that introduction of new genes from domestic animals can lead to hybrid vigour in wild populations. The authors suggest that, if the trend continues, wild dogs are likely to engage in prey-switching behaviour (i.e. predate on larger animals than previously)."
It should be noted that this is based on an unpublished study and therefore unlikely to have been peer-reviewed for accuracy of data or conclusions.
Studies have shown that dingoes are more closely related to other domestic dogs than to grey wolves or coyotes, meaning they are domestic dogs that went feral. Australian Dingoes may have a common shared origin with New Guinea singing dogs. "Pure" dingoes had low genetic diversity, meaning they probably came from a single small founding population originating from East-Asian domestic dogs taken to Australia around 4,600 - 5,400 years ago. Alternatively, dingoes lost their genetic diversity through one or more severe genetic bottlenecks at an early stage. Theoreteically, the current pure dingo population could have resulted from a single female and her young. In either case, they remained almost isolated from other domestic dogs and evolved into a consistent type. The DNA analysis indicated that there had not been any significant introduction of other domestic dog on the Australian continent prior to the arrival of Europeans. In other words, the Dingo population has become inbred and genetically uniform.
During European colonisation, there was an influx of European domestic dogs. Some strayed or went feral and interbred with the dingoes. There are now very few populations of the original pure dingo and an estimated 78% of wild dingoes are mongrels (the frequently used term "dingo-hybrid" is incorrect, as dingoes are a variety of domestic dog, not a distinct species). These mongrels differ in conformation, colouration and reproductive habits from pure dingoes. While pure dingoes adapted to the Australian environment to produce only one litter per year, European domestic dogs can produce two or more litters annually. Their greater reproductive success has been aided by the greater availability of prey in the form of introduced goats and sheep. Studies have verified that there is a wider range of fur-colours, skull-shapes and body size in the modern Australian "wild" (i.e. feral) dog population than in the time before the arrival of Europeans. Since the 1970s, there has been an approximately 20% increase in their average body size.
Like the feral cat, the feral dog is considered a pest. Conservation of the "pure" dingo in its original form is controversial and is based on heritage, cultural and ecological factors. While some researchers believe that the larger "dingo hybrids" could be super-predators, others belive that the "pure" dingo could be supplanted by these larger "dingo hybrids" without unduly disturbing the dynamics of the various ecosystems in which they live.
It is not simply "hybrid vigour" that boosted the size and weight of the dingo population, it is the type of dog that has bred with dingoes. Looking at four of the most popular dog breeds it is notable that they all weigh between 14 and 40 kg and would contribute genes for greater size. In the absence of environmental pressure, a genetically diverse feral population tends to revert to the ancestral size and weight. The genetically uniform "pure" Dingo is undersized in comparison to the wolf (the ancestor of domestic dogs).
With so many of these larger breeds kept as pets and with the potential to stray there is a large and continuing influx of genes into the dingo population and a greater potential for genetic drift. In comparison, there are few larger-than-average domestic cat breeds (Ragdoll, Maine Coon) and the F5 Savannah is within the normal size range for domestic cats. Traditionally, male pet dogs are less commonly castrated than male cats (this is due to behavioural reasons - uncastrated cats spray indoors while uncastrated dogs urine-mark outdoors). In this instance, the average size of the dingo has been influenced by the ongoing influx of domestic (pet) dog genes.
Dogs are a domesticated form of wolf and are sociable pack hunters that evolved to tackle larger prey. The purported "super-dingoes" demonstrate a reversion to the ancestral type rather than the evolution of a new super-predator. The presence of livestock (introduced species whose hard hooves devastate Australian grasslands) mimics the herds that wolves naturally prey upon. The Australian environment has been manipulated by humans to favour larger canine predators.
Other Comparisons based on Gene Mixing
Other examples where mixing of genes from divergent sources of the same species has led to greater invasiveness include: green anole lizards in Florida and Hawaii, European rabbits in Australia and European green crabs in North America (Zenger et al 2003, Kolbe et al 2004, Kelly et al 2006). The possibility of Savannah cats contributing to the already effective invasiveness of feral cat populations cannot be dismissed. "
Anole Lizards in the USA
The situation with Anole lizards has been over-simplified by the IA CRC, perhaps deliberately to support their case against the Savannah cat. There are over 36 species of non-native Anoles breeding in the wilds in Florida, with considerable interbreeding. In fact, referring to some of these as "species" is a matter of convenience as they are completely interfertile and appear to be geographically separated strains of a single species.
The Cuban Green Anole (Anolis porcatus, Anolis carolinensis porcatus) was introduced into Florida in the 1980s. It is genetically almost identical to, and fully interfertile with, the Carolina Green Anole (A carolinensis) forming numerous intergrades between the two types. It appears to be the parent of the Carolina Green Anole. They are regarded as separate species as a matter of convenience, not a matter of genetics (Buth, Gorman and Lieb, 1980). It is successful along forest edges and disturbed habitats, including streets, parks and back yards. It is better adapted to coexist with humans, another example of where humans have manipulated the habitat to favour an introduced variety over a more delicate native variety. Rather than displacing the native species, they are melding back into a single species.
The main invasive threat to the native Carolina Green Anoles is the more aggressive Cuban Brown Anole (Anolis sagrei, Norops sagrei) introduced into Florida in 1887 and also into Hawaii. Some authorities now place this in genus Norops. The Brown Anole is a habitat generalist that generally prefers open vegetation within disturbed sites and urbanized areas and is well-adapted to coexist with humans. Its spread is helped by human intervention e.g. in nursery plants. Two subspecies (a distinction based on geographical origin rather than genetic differences), the Bahaman Brown Anole (A sagrei ordinatus) and Cuban Brown Anole (A sagrei sagrei) were introduced and have extensively interbred into a single indistinguishable species. There is no evidence that this interbreeding has made them more invasive.
Green Anoles are relatively delicate and easily stressed. Brown Anoles are hardier, have a more diverse diet (including juvenile Carolina Green Anoles), are more prolific and less easily stressed, but more vulnerable to the cold. Evidence suggests that the more adaptable Brown Anole is responsible for the decline in Carolina Green Anoles in human-altered habitats. Brown Anoles are more terrestrial and prefer lower perches; they displace green anoles to higher in trees. Brown Anoles can also introduce blood parasites into new areas where they can infect the Carolina Green Anole. Carolina Green Anoles are also captured for the pet trade; they are less hardy than the Brown Anole and may fare less well in captivity.
Male Brown Anoles mature around 44 mm and females mature around 35 mm. In Florida, females Brown Anoles can lay a single egg about every 6 days from mid-March to mid-September (a longer breeding season than in its native habitat). The male Carolina Green Anole matures around 48 mm and females mature around 41 mm i.e. both they must attain larger size than the Brown Anole in order to reproduce. Carolina Green Anoles also have a shorter breeding season: April to August/September. Female lay 1-2 eggs at intervals throughout the season, until she has produced around 10 eggs. Carolina Green Anole hatchlings are vulnerable to predation by the more terrestrial Brown Anoles (adults of both species eat juveniles, but the Brown Anole is more rapacious and also prefers the juveniles of other species). In Florida, both species probably live no more than 18 months.
The decline in the native Carolina Green Anole results from the introduction of not one, but several, non-native lizards, some of which have melded with it, while others are more adaptable or more prolific breeders or predate upon the Florida native. There are other complex interactions between native and introduced Anoles making it is erroneous to simplify this into the argument that the mixing of genes from divergent sources of the same species has led to greater invasiveness.
European Rabbits in Australia
The rabbit's success was partly due to the absence of predators, protection by humans and the release of fast-maturing commercial strains rather, resulting in a "founder effect". Whereas Serval genes from a Savannah cat would be swamped out by the already widespread "moggy" strains, rabbits were released into previously rabbit-free habitat with few natural controls and were initially encouraged to become established and to breed.
Rabbits were first introduced into Australia in 1788 as captive food animals, but did not become numerous except in Tasmania. By the 1820s they were bred as cage animals around houses in New South Wales, but there were no wild rabbits in enclosures (i.e. managed warrens). Apart from the localised rabbit plague in Tasmania, there were no rabbit outbreaks at the European settlements in southeastern Australia. Native Quolls were probably effective killers of any escaped rabbits. Quoll numbers declined due to urbanisation and competition with/predation by foxes and cats. As rabbits are not the preferred prey of foxes and cats, the rabbit population suffered less predation and expanded. The Thylacine had already vanished from mainland Australia, though in Tasmania the rabbit became a common prey species for Thylacines and there are accounts of them hunting rabbits. Systematic extermination of the Thylacine by colonists removed a natural control on the rabbit population.
The modern rabbit infestation originated with the release of 12 wild rabbits by Thomas Austin at Barwon Park, near Winchelsea, Victoria, in 1859 so he could enjoy game-shooting. His founding population of rabbits were supplied by William Austin in England who supplied a mix of wild and domestic rabbits. One theory as to why the Barwon Park strain adapted so well to Australia is that the resulting hybrid rabbits were particularly hardy and vigorous. The influence of domestic rabbits is not due to mixing of genes increasing invasiveness, it is due to the "founder effect. With only 12 rabbits released, there would have been a founder effect: a type of genetic drift that occurs when a new population is established from a very small number of individuals. The Barwon Park strain was founded from a small gene pool that included domestic rabbits. These would not have been fancy (pattened or lop-eared) rabbits, but commercial meat rabbits from strains developed in England for fast maturation, an efficient metabolism (for fast growth) and high reproductive rate. Had they been fancy strains, the Australian population would have more patterned animals like those in island populations of off Scotland and Wales (areas similarly lacking in natural predators). Later on, other farms released their rabbits into the wild, though the Barwon Park strain would already have been the prevalent type.
Europeans settlers turned the native scrub and woodland into vast areas of low vegetation that favoured the spread of rabbits. By 1868, the population numbered in the millions and were a valuable source of food and pelts. Like other livestock, they were protected by humans and digging out warrens was considered a malicious and punishable act. Not until 1901, were they recognised as a pest and various methods were used to try to control them. Rather than any concern for the habitat or native herbivores, rabbits were deemed a pest because they competed with more economically valuable introduced graziers such as sheep and cattle (that also cause environmental damage). The bottom line is economic value rather than protecting native species, as is evidenced by the culling of native graziers such as kangaroos because they compete with, and are less valuable than, sheep!
It was not merely a "mixing of genes from divergent sources" that caused the rabbit's invasiveness. It was the introduction of a founding strain that had been bred for fast maturation and efficient reproduction into an environment already changed by human actions, and where their breeding warrens were protected because of their value as game/livestock. This founder effect in Australian rabbits, is comparable to the Boolarra Carp, but is not comparable to an escape of a low number of Serval genes from F5 Savannahs into an existing large population.
European Green Crabs in North America
The European Green Crab or European Shore Crab (Carcinus maenas) is native to temperate European and North African coasts, but has colonised similar habitats around the world. It grows to 6 cm (2.4 inches) long and 9 cm (3.5 inches) wide. It is a voracious eater with a wide diet including bivalves, worms and small crustaceans. In its native range it is an important scavenger. It reached foreign shores through human intervention: on ships' hulls, in ballast water, in packing materials (seaweeds) used for transporting live bivalves. When "seeding" fisheries with bivalves, crab larvae are often introduced at the same time. Once established, the crabs can raft shorter distances on drifting material, and the main method of expansion is by dispersal of larvae on sea currents. Many of the world's temperate coastlines provide a suitable habitat and maritime trade has caused its spread. It arrived in North America in 1817, and is now widely distributed along both east and west coasts of North America. It arrived in Victoria, Australia in the late 1800s, South Africa in the 1980s and Tasmania in the 1990s.
It inhabits a wide range of coastal habitats (sandy, rocky, muddy, marshy), tolerates a wide range of salinities and a temperatures between 0 - 30 Centigrade (32 - 86 Fahrenheit). Larvae are less tolerant of variations in temperature and salinity which may limit their spread. Adults can tolerate starvation for up to 3 months, and survive in damp burrows for several days. The larvae develop offshore in several stages before becoming juvenile crabs in the intertidal zone. The young crabs live among seaweeds and seagrasses. The colour (green, brown, grey or red) is affected by genetic and environmental factors. Red individuals are stronger and more aggressive, but are less tolerant of environmental stresses, such as low salinity or low oxygen levels. A variety of predators take the crabs at various stages of their lifecycle.
In their native range in Northern Europe, the crabs typically take 2 years to reach sexual maturity, but can mature within 1 year in North America. Growth is influenced by food supply and seasonal temperature fluctuations and they grow more rapidly and reach a larger size than crabs in the native range (Grosholz & Ruiz 1996, Ruiz et al. 1998). Adult females may produce more than one clutch per year averaging 185,000 eggs per clutch, fertilized using sperm she stores after mating. It takes approximately 90 days for these to pass through the larval stages and become juvenile crabs. Females live about 3 years, while males live about 5 years.
Green Crab genetic diversity is maintained by international maritime traffic/trade. The population in California could have been transported directly from Europe, eastern North America, Australia or South Africa. There is no firm evidence that the mixing of genes from diverse sources has increased invasiveness of European green Crabs in North America, though is has prevented deleterious levels of inbreeding. The main factors contributing to invasiveness appear to be available mechansims aiding spread: marine traffic, inadvertant introduction into shellfish seed beds and spread of larvae on coastal currents. Mixing genes (from both native and non-native populations) has not made a previously non-invasive species invasive.
For completeness, there may be a case of hybrid vigour increasing invasiveness in crabs, but in Japan, not in North America as suggested by the material opposing the importation of Savannah cats. The similar Mediterranean Green Crab, C. aestuarii, is sometimes considered to be a subspecies of the European Green Crab (C maenas), but DNA studies found substantial differences between them. In Europe, the Mediterranean Green Crab replaces the European Green Crab in the warmer Mediterranean and there appears to be "hybrid zone" where their native ranges overlap. While the European Green Crab has invaded many temperate shorelines throughout the world, the Mediterranean Green Crab (in a hybrid form) has not been invasive, possibly being less tolerant of variations in water temperature or quality. Mediterranean Green Crab x European Green Crab hybrids have only been invasive on the coastline of Japan.
Interspecific hybridization can aid adaptive evolutionary change. Like random mutation, it is hit or miss, for example hybrid Heliconid butterflies the hybrids are disadvantaged compared to the parent species. In the right circumstances, it can dramatically influence the establishment and invasiveness of a population. In Japan, the non-native European Green Crabs show mitochondrial (i.e. maternal) lineages derived from both species of crab, but nuclear lineages are predominantly from the Mediterranean Green Crab. The hybrids are stable in phenotype and genotype, indicating that the crabs introduced into Japan were already hybrids. It is possible that hybridisation back in the Mediterranean resulted in a more invasive form of Mediterranean Green Crab (more tolerant of variable temperature/water quality). However, this is still not comparable to the introduction of F5 Savannah cats whose low percentage of Serval genes would be a "drop in the ocean" compared to the ongoing interbreeding between crab species with overlapping native ranges, followed by a "founder effect" where hybrid crabs colonised waters that may have been inimicable to one or both parental species.
Boolarra Carp in Australia
As already pointed out, the invasiveness of the Boolarra carp was not due to hybrid vigour, but was a result of deliberately importing and farming huge numbers of a strain selected for its robustness and prolificacy. No hybridisation (mixing of genes) was necessary for the new strain of carp to out-compete previously imported strains.
Risk Assessment and Mitigation
DEWHA used Bomford’s 2003 model "Risk assessment for the import and keeping of exotic vertebrates in Australia" and applied it correctly in the opinion of the IA CRC. IA CRC were aware of Dr. Bomford’s modification of the model and made their own assessment using his most recent (unpublished) "Risk Assessment Models for Establishment of Exotic Vertebrates in Australia and New Zealand". This analysis still resulted in an ‘Extreme’ risk of establishment, but it was noted that parameter B4 (non-migratory behaviour) was not considered a risk parameter for mammals in the updated model which gave a revised score of 15/15 rather than 15/16. "Queensland Pest animal risk assessment (Savannah)" use Bomford's 2008 model but their risk assessment was based on comparison with the wild Serval based on their misunderstanding of Filial generation numbers.
DEWHA and IA CRC believe that risk mitigation proposals by importers are inadequate. IA CRC did not believe that animals containing a percentage of African Serval genes were appropriate to be kept by private citizens. They agreed with the DEWHA Draft Risk Assessment that it is inevitable that some of these animals will escape, be dumped or mate with others cats, such that their genes will find their way into the feral population.
Risk mitigation proposals by Savannah cat importers were considered admirable in that they encourage responsible pet ownership. However, it is intended that these animals be held by private citizens with no ongoing certification and/or inspection process. It was considered feasible that some of these cats will not prove to be perfect pets at all, with their jumping and hunting abilities, and will consequently be dumped, or escape from ineffective household enclosures.
The proposed Savannahs were the F5 generation and their jumping and hunting abilities are comparable to the Oriental/Siamese already present in Australia, rather than comparable to the Serval's abilities. The DEWHA and IA CRC arguments are skewed by considering the F1 or F2 generations (which are larger and more athletic) rather than considering the F5 and later generation.
DEWHA and IA CRC considered risk mitigation proposals by importers to be "manifestly inadequate". The felt that a decision to allow the importation of Savannahs would be used as precedent for other future importers, and that confinement procedures would be unenforceable over the longer term with these animals in private homes. The precedent for the presence of hybrid cats in Australia had already been set by the importation of the Bengal. These have proven to be no riskier than other domestic breeds. DEWHA and IA CRC consistently failed to specifically consider representative specimens of the F5 generation and based their arguments and (foregone) conclusions on the traits of hybrids only 1 or 2 generations removed from the Serval, rather than hybrids 5+ generations removed from a wild ancestor. This failure to properly and specifically consider the generation proposed for importation makes their conclusions inaccurate.
Savannah cats could enter Australia with people settling in the country simply by declaring them non-pedigree domestic pet cats. The Bengal (containing both Asian Leopard Cat and Margay genes) is already legal to own and similar in appearance to non-experts.
The desirability of F1 or F2 Savannahs (in the unlikely event of them being independently developed in Australia) could be reduced by putting strict conditions on ownership e.g. licences, housing, inspection, similar to Britain's Dangerous Wild Animals Act (1977). This would also act as a deterrent to casual ownership of such cats.
Supply and Demand/Breed and Rescue
IA CRC believed that the high price of Savannah cats would not ensure adequate security. They supported this by noting that a simple Google search revealed dozens of advertisements for low-priced Savannah cats in the United States. The low-priced "Savannah" cats in the USA are generally from backyard breeders and cannot be registered with TICA. Such cats often come from Savannahs that were sold as "pet quality" and "not for breeding" and where the purchaser did not honour the neutering contract, but instead bred the cat for profit. This could have been reduced by neutering Savannahs before selling or rehoming them, including early-age neutering if necessary. Other low-price purported Savannahs are likely to have been bred by owners of pet Servals cashing in on the trend.
"Australian experience with many animals new to the market has shown that prices often crash once the small breeding market is saturated. In the USA, the Savannah Cat Club has established Savannah Cat Rescue. These cats do escape and get dumped in the USA and that will also happen in Australia." According to Savannah Rescue, those that are relinquished by their owners are mostly F3 and F4 Savannahs. They are not "dumped" or escapees but are surrendered for exactly the same reasons as any other domestic cat: change in personal circumstances (e.g. loss of home/job); family members developing allergies; moving to a "no-pets" apartment; new partner allergic/hates cats; old wives' tales that the cat will smother the new baby; moving to an area where hybrids are restricted/banned.
The crash in price in Australia occurs where supply of a novel pet outstrips demand. Controls over the number of cats permitted to be kept by breeders can help prevent this by penalising breeders that produce too many litters in a given period. In the USA, the price of TICA-registrable Savannahs has reduced, but not crashed. Price crashes in other breeds (both cats and dogs) is related to backyard breeders mass-producing animals to cash in on the market, but with no regard of the animals' health. Such breeders consider kittens to be a product or cash crop and have no interest in the breed except as a commodity; the purchasers are often disappointed to discover their cat is not the "genuine article". These "lookalikes", often with multiple health or behavioural issues from poor breeding practices, are the ones more likely to end up in animals shelters.
All reputable breed clubs will set up an associated rescue arm. Breed rescues take the pressure off of other cat shelters and, due to the low numbers involved, are more able to concentrate on matching rescued pedigree cats to suitable owners. The existence of a breed rescue recognises that owners and breeders can face changes of circumstances (or die) and does not necessarily mean highly desirable hybrid breed cats are already being dumped or straying. In the USA, the waiting list for rescued Savannahs outstrips the number surrendered.
IA CRC notes "Australian RSPCA euthanizes about 33,000 cats annually, meaning that the likely total of cats euthanized annually in Australia exceeds 50,000. There is no shortage of cats for Australians to own if they wish to do so." This overlooks that fact that people who covet a spotted wildcat (such as an Ocelot, Margay, Serval or even a Leopard) are unlikely to be attracted to an ordinary domestic cat. They are specifically attracted to the appearance of a spotted wildcat. Where it is not feasible to own the wild species, a domestic breed with hybrid ancestry is the next best thing. Because of the price-tag and the desirability of the wild look, the people likely to obtain Savannah cats are those who are unlikely to obtain non-pedigree cats. It is, therefore, a fallacy that barring the Savannah will increase the adoption of cats. Instead, the potential owners will seek out other exotic-looking breeds such as the Bengal, and Bengal breeders may increase the number of cats bred to meet this demand (the dark side of this will be kitten farms).
"Three quarters of Australians currently rate cats as the worst feral animal in the country (Fisher and Cribb, unpublished), second only to the cane toad and well ahead of the third-rated feral, the rabbit."
A large amount of anti-cat propaganda fuels these opinions to ensure that the cat has a high profile as a pest. The general public has a short attention span and is relatively easily manipulated by the media. In this respect, humans exhibit a form of herd mentality and follow fashions and trends. Were another introduced species to be spotlighted in the same way with consistent negative publicity, the public perception would reflect the way in which that species were presented. The structure of the statement aims to mislead the reader. The careful positioning of the parenthesised phrase ensure it suggest that the public rates cats as the worst feral animal, period. It ensures that this is the phrase and perception that will remain in the reader's memory. This is a trick often employed by the tabloid media to influence reader opinion. In fact the cat is rated second worst after the Cane Toad. it should be noted that this "fact" is based on an unpublished, and therefore not peer reviewed study. The study parameters are not provided - the numbers involved in the survey and the geographical range of the survey. Without a published study behind it, the survey could have involved as few as four people asked to rate only those three introduced animals!
The prohibition of the Savannah cat in Australia is based on flawed data. The Australian reports make comparisons of F5 Savannahs (that are within the size, weight and activity range for domestic cats) with the wild Serval or with F1/F2 Savannahs. It fails to understand the early generation sterility issue or the use of filial generations (F numbers) and therefore overstates the percentage of Serval genes in an F5 Savannah. It uses inappropriate comparison studies to argue that hybrids "supercharge existing populations". It erroneously claims that a specialist Savannah rescue organisation exists due to cats escaping or being "dumped" and relies too heavily on the anti-hybrid propaganda of a single big cat "rescue" organisation that appears not to properly understand domestic cats and makes unfounded claims to the effect that the Savannah represents a danger to humans.
Including articles referenced by the Invasive Animals Cooperative Research Centre (IA CRC) and Department of the Environment, Water, Heritage and the Arts (DEWHA)
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