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SPECIES PROFILE Siberian Tiger Panthera tigris altaica Photo sourced from: https://en.wikipedia.org/wiki/Siberian_tiger#/media/File:Panthera_tigris_altaica_13__Buffalo_Zoo.jpg January 2016 Elyshia Wignell BSc (Zoology) Donna Cuttriss This publication should be cited as: Wignell, E. & Cuttriss, D. (2016) Species Profile: Siberian Tiger (Panthera tigris altaica). Zoodoo Zoo. Richmond, Tasmania. About this Pest Risk Assessment This pest risk assessment is developed in accordance with the Policy and Procedures for the Import, Movement and Keeping of Vertebrate Wildlife in Tasmania (DPIPWE 2011). The policy and procedures set out conditions and restrictions of the importation of mammals, birds, reptiles and amphibians pursuant to s34 of the Nature Conservation Act 2002. This pest risk assessment is prepared by Zoodoo Zoo for the use within the Department of Primary Industries, Water and Environment, Tasmania. For more information about this Pest Risk Assessment, please contact: Elyshia Wignell Zoodoo Zoo Pty Ltd Address: 620 Middle Tea Tree Road, RICHMOND Tasmania, 7025 Phone: (03) 6260 2456 Email: [email protected] Visit: www.zoodoo.com.au Disclaimer The information provided in this Pest Risk Assessment is provided in good faith. Zoodoo Zoo and its employees do not accept liability however arising, including liability for negligence, for any loss resulting from the reliance upon the information in this Pest Risk Assessment. 1. Summary The Siberian tiger (Panthera tigris altaica) is one of the 7 listed sub-species of tiger and is the largest, and most northernmost, of the 5 remaining sub-species. Their historical native range covers up to 300,000km² (Tian et al. 2011) and includes far south-eastern Russia, northern China and east Mongolia, the Korean peninsula and extends as far as the Sea of Japan (Tian et al. 2011; Alasaad et al. 2011). No feral populations of Siberian tigers have ever been known to establish and the preferred habitat type for Siberian tigers includes areas with monsoonal climates and Korean pine forests.Therefore, this species is considered to be highly unlikely to be able to establish populations in Tasmania. The Siberian tiger is listed as ‘Endangered’ by the IUCN, due to poaching, habitat loss and degradation, as well as having a scarce prey source due to overhunting by humans. In Tasmania, the Siberian tiger is likely to be categorised as a ‘controlled animal’ under the Nature Conservation Act 2002. The Vertebrate Pest Committee (VPC 2007) has assessed the Siberian tiger as an ‘extreme’ threat species. Therefore, collections of this species may only be kept under permit for either education, conservation, entertainment and/or exhibition purposes (VPC 2007). 2. Introduction 2.1 NAME AND TAXONOMY Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Felidae Genus: Panthera Species: Panthera tigris altaica Sub-species: Other tiger Sub-species include: Bengal Tiger (Panthera tigris tigris), Indochinese Tiger (Panthera tigris corbett), South China Tiger (Panthera tigris amoyensis), Sumatran Tiger (Panthera tigris sumatrae), Javan Tiger (Panthera tigris sondaica), Bali Tiger (Panthera tigris balica) and the Caspian Tiger (Panthera tigris virgata). However, the Javan, Bali and Caspian Tigers are all declared extinct (Dybas 2011; IUCN 2011). Common names: Siberian tiger and Amur tiger Known hybrids: It is possible for lions and tigers to mate and create hybrids and there are two kinds of lion/tiger hybrids. If a female lion is mated with a male tiger the hybrid is known as a ‘Tigon’, however if a female tiger is crossed with a male lion the hybrid is referred to as a ‘Liger’. Both types of hybrids create offspring that grow to be considerably larger than either of their parents and male offspring are always sterile. Most female offspring are also sterile, however a small percentage are able to breed and when such breeding occurs her offspring are then referred to as either li-ligers or ti-tigons (Baker 2006). 2.2 DESCRIPTION Genetic analysis shows that the Siberian tiger has the lowest genetic diversity of all the remaining sub-species (Alasaad, Soriguer, Chelomina, Petrovich Sushitsky and Fickel 2011). Furthermore, the Siberian tiger is the largest, heaviest and most northernmost of the remaining sub-species (Tian, Wu, Smith, Wang, Kou and Ge 2011; Song, Hua, Song and Zhang 2007). Male and female Siberian tigers can weigh up to 320kg and 160kg, respectively, and have a head-tail length of 3.3m for males and 2.6m for females (Baker 2006 & 18). Additionally, Siberian tigers have the least amount of stripes (after the South China tigers) (Tilson 2016), are thought to have lighter and less dense stripe patterns and a coat length much longer than that of the other sub-species, ranging between 40-105mm in length, compared to a length of between 7 and 35mm for all other tigers (Baker 2006). Such differences in stripes, size, weight and coat length are all due to the much harsher and colder conditions experienced in the home ranges of the Siberian tiger (Baker 2006; Kerley et al. 2003). 2.3 CONSERVATION AND LEGAL STATUS CONSERVATION The Siberian tiger is currently listed as ‘Endangered’ by the ICUN, since it was downgraded from its ‘critically endangered’ listing in 2008 (IUCN 2011). There is thought to be less than 400 individuals remaining throughout the entire world (Fukui et al. 2013). LEGAL STATUS In Tasmania, the Siberian tiger is a ‘controlled animal’ under the Nature Conservation Act 2002. The Vertebrate Pest Committee (VPC 2007) has assessed the Siberian tiger as an ‘extreme’ threat species. Therefore, collections of this species may only be kept under permit for either education, conservation, entertainment and/or exhibition purposes (VPC 2007). This species is listed under CITES Appendix I (Liu et al. 2014). 3. BIOLOGY AND ECOLOGY 3.1 LIFE HISTORY Unlike most tiger sub-species Siberian tigers are thought to be seasonal breeders, most likely due to the harsh environmental conditions they face in their wild habitat (Kerley, Goodrich, Miquelle, Smirnov, Quigley and Hornocker 2003). It is estimated that most Siberian tiger young are conceived between March and May (however, it has been demonstrated to be as early as January and February) (Kerley et al. 2003), which corresponds with Siberian tiger births occurring most often between August and October (Kerley et al. 2003). A 7-8 month period of anoestrous is not uncommon for Siberian tigers, however would be extremely unusual for all other tiger sub-species who are capable of ovulating all year round (Tilson 2016). As tigers are solitary animals, individuals use scent markings as a way of finding each other when it is time for mating (Tilson 2016). The males’ ability to find the female based on her scent markings is extremely important, as females are only receptive for approximately 2-3 days of their entire oestrus cycle (Baker 2006). To further complicate things for the male, Siberian tigers are induced ovulators and therefore they must receive a certain amount of copulations, during a particular time, in order for their ovulation to be stimulated (Tilson 2016). To assist the males to ensure that they are present at the appropriate time, when they are available for mating, females will begin scent marking much more frequently (Baker 2006). Furthermore, males are also equipped with an unusual ‘cone-shaped’ penis that has a ‘baculum’ (bony-like structure) covered with over 100 backwards facing barbs, each of these features assist the male with stimulating the female to ovulate (Baker 2006). During oestrus females are characterised by behaviours such as, vocalisation, rolling on the ground in front of males, as well as spitting and striking at males. Eventually, the female will accept a male and allow him to get closer without aggression (Baker 2006). Once chosen, tigers pair and will copulate up to 52 times a day (approximately 15 seconds each) for approximately two days (sometimes up to 7), after which the male will leave (Tilson 2016). Should copulation be unsuccessful, the female will return to oestrus 25- 30 days later and the male will return to try again. During times when the female is sexually receptive, and therefore is not raising cubs, she will continue to cycle every 25-30 days throughout the breeding season (Tilson 2016). During each oestrus, females may be stimulated by more than one male and therefore it is possible to have cubs within a single litter who have been fathered by different males (Baker 2006; Tilson 2016). Gestation lasts between 102 and 105 days (Shoemaker, Maruska and Rockwell 1997) and the female can have between 1 and 6 cubs, however the average litter size is often between 2 and 3 (Tilson 2016). Approximate birth interval between the first and last cub is between 2 and 4 hours (Tilson 2016). At birth all cubs are blind and toothless (Tilson 2016). Eyes do not begin to open until approximately 7 days old, however it can be up to 12 days, and their full set of milk teeth have usually emerged by 1 month of age (Baker 2006). Solid food does not begin to be eaten until between 6 and 8 weeks and their permanent canine teeth are not fully emerged until between 16 and 18 months of age (Tilson 2016). The birth weight of tiger cubs averages between 785 and 1610g (Baker 2006 & 18), but their weight increases rapidly and by 6 months of age males and females weight around 40-50kg and 26-36kg, respectively. Weight differences between the sexes only increase as they get older, with males weighing up to 45kg more than females at around 18 months of age (Baker 2006; Tilson 2016). Siberian tigers can continue to grow until they are up to 5 years old, with slow growth being demonstrated more often in males than females (Baker 2006). Average inter-birth interval for Siberian tigers is approximately 21.4 months, however should the cubs die, females are capable of giving birth up to 3 times a year. Furthermore, should a new male wish to mate with a female who has young cubs, it has been demonstrated that this male will kill her cubs in order to stimulate her oestrus cycle and therefore produce offspring of his own (Baker 2006). The mortality rate of Siberian tiger young, in both the wild and captivity, is relatively high with an estimated 40% mortality occurring within the first 2 months of life and approximately only 1-2 young from each litter surviving to be past 2 years of age (Kerley et al. 2003; Tilson 2016). Over the lifetime of a tigress, it is estimated that between 13-18 young can be produced, under ideal conditions. However, only around 50% of those young are likely to survive into adulthood (Kerley et al. 2003). There is much debate amongst scientists as to how quickly Siberian tigers are capable of increasing their population numbers. For instance, some researchers believe that when Siberian tigers are properly protected, and have access to an abundance of prey, they are productive breeders and therefore allow for fast population growth (Miquelle, Smirnov, Zaumyslova, Soutyrina and Johnson 2015). However, given that Siberian tigers are demonstrated as having one of the latest ages at first birth and one of the longest interbirth intervals of all tiger sub-species, other researchers argue that the population growth of Siberian tigers would be one of the slowest of all the large felids. More research needs to be done in this area to determine which of these theories is likely to be the most accurate (Miquelle et al. 2015). Tigers are considered as being quite maternal species and it is estimated that approximately 70% of their day consists of nursing their newborns during the first 10 days, after this it drops to approximately 60% until around 40 days when it drops again to approximately 30%. At three months of age the cubs begin to be weaned and the female only spends approximately 10% of her day nursing (Baker 2006). In order to keep up with the feeding demands of her cubs, the female must increase her killing rate by as much as 50%, and therefore must spend significantly more time hunting when she has cubs. As a result, females must be in a good condition prior to pregnancy in order to survive the demand once her cubs are born (Baker 2006). Although cubs are weaned between approximately 3 and 6 months of age, they will remain with their mother until between 17 and 24 months of age, during which time she teaches them appropriate social behaviours and how to hunt (Baker 2006). However, males tend to become more independent than females and at 15 months of age it is not uncommon for males to wander away from their mother for a few days at a time. Females will often create their home territories next door, or in close proximity, to their mother’s territory, whereas males will disperse much farther (Baker 2006). Tigers become sexually mature between 3-4 years of age, however males often have to wait longer to breed than females as they must fight other males to gain territories and therefore to gain access to females (Baker 2006). Additionally, it is estimated that males will cease breeding at a younger age than females. However, this is thought to be mainly due to their reduced ability to hold territories as they get older, more-so than their inability to copulate as males are thought to remain fertile for up to 14 years, compared to approximately 12 years for females (Baker 2006). Mortality amongst tigers significantly increases once they reach the age of 12 (Baker 2006; Tilson 2016). 3.2 HABITAT REQUIREMENTS AND PREFERENCES Siberian tigers are commonly found within northern and cold temperate zones where there is a monsoon climate, characterised by winters that are cold and windy (Kerley et al. 2003) and have between 75 and 85% of its precipitation occurring as rain between April and November (Goodrich, Seryodkin, Miquelle and Bereznuk 2011; Tian et al. 2011). However, slightly warmer and moister climates, such as the Sikhote-Alin mountains, may also be home to Siberian tiger populations (Tian et al. 2011). Siberian tigers can be found as high as 3000m, above sea level, within this area. However, it is believed that latitudes above this height consist of climates that are too harsh and cold for their survival. The habitat that appears to be favoured by Siberian tigers includes broadlevel, Korean pine forests of latitudes up to 3000m, as these are considered to be some of the most diverse forests in the world (Tian et al. 2011; Alasaad et al. 2011). Habitats that consist of deciduous, or coniferous mixed with deciduous, trees and that are highly forested are by far the preferred habitat type of Siberian tigers (Miquelle, Rozhnov, Ermoshin, Murzin, Nikilaev, Hernandez-Blanco and Naidenko 2015). Therefore, tigers will rarely be found living in open habitats such as wetlands or agricultural fields (Baker 2006). On top of their preference for monsoonal climates and Korean pine forests, Siberians tigers are also thought to prefer habitats with lower human population densities (Alasaad et al. 2011). Although there are approximately 17 patches of suitable habitat in Russia, spanned across 155, 000km², unfortunately only 2 of these patches are interconnected and therefore the movement of tigers throughout each of these patches is extremely limited (Miquelle and Rozhnov et al. 2015) 3.3 NATURAL GEOGRAPHIC RANGE Historically, Siberian tigers had a distribution that covered up to 300,000km² (Tian et al. 2011) and included far south eastern Russia, northern China and east Mongolia, the Korean peninsula and extended as far as the Sea of Japan (Tian et al. 2011; Alasaad et al. 2011). Within this area exists a variety of mountain ranges, including the Sikhote-Alin mountains, the Khingan (Xing’an) mountains, as well as the Changbai and Wandershan mountains, each of which are characterised by high levels of forestation and therefore provide the preferred habitat type for Siberian Tigers (Tian, Wu, Wang and Ge 2014). In the late 1800’s it was estimated that throughout this range there were approximately 3000 Siberian tigers remaining (Tian et al. 2011). Today, however, there are approximately only three major distribution areas in which Siberian tigers are found, the Sikhote-Alin mountains, the Changbai and the Wandershan mountains (Tian et al. 2011). Furthermore, in north eastern china, it is estimated that as little as 20 individuals remain (Liu et al. 2014) and in far eastern Russia, only approximately 128,000km² is occupied and less than 400 individuals are assumed to remain (Goodrich et al. 2011). It is estimated that as little as 7% of the historical range of the Siberian tiger is now occupied (Dybas 2011). 3.4 INTRODUCED GEOGRAPHIC RANGE There is no evidence of the Siberian tiger ever establishing feral, non-naturally occurring, populations outside of their native geographical range. Furthermore, this species is not currently, and has never been, recorded on the Global Invasive Species Database (Global Invasive Species Database 2015). 3.5 POTENTIAL DISTRIBUTION IN TASMANIA Using the CLIMATCH modelling application by the Bureau of Rural Science, a climate comparison between the species’ distribution (both previous and current) and potential Australian distribution is shown in Figure 1. This modelling indicates that Australia has no areas in which the climate is similar to the natural range of Siberian tigers. Furthermore, Tasmania’s climate is demonstrated as being highly dissimilar and therefore is not suitable for this species to establish populations (highest climate match score = 0). Figure 1. Climate comparison between the historical range of Siberian Tiger and Australia, where 10 is a ‘perfect’ match and 0 is having a very dissimilar climate. Tasmania shows a match of all zeros and therefore has a very dissimilar climate to the natural historical range of Siberian tigers. 3.6 DIET AND FEEDING BEHAVIOUR Siberian tigers (and all other tiger subspecies) are carnivores (Baker 2006) and their preferred prey species is thought to be red deer and wild boar (Tian et al. 2014). However, other prey types such as Sika and Roe deer, Siberian and Maral Wapiti (Elk), Asian black bears, badgers and racoon dogs will also be readily hunted and consumed by Siberian tigers (Hernandez-Blanco et al. 2015; Baker 2006). Much like other cat species, tigers have also been known to consume grass as a source of roughage (Baker 2006). Tigers will devour all, or almost all, of any prey species they kill, including bones, fat and visceral organs and therefore nothing goes to waste (Baker 2006). Due to the harsh climate experienced within their habitat, prey density for Siberian tigers is often low (Kerley et al. 2003) and they are estimated to have a successful kill ratio of only 1 in every 20 attempts. Therefore, it is assumed that tigers will often choose to hunt the largest of their prey species available (Baker 2006) as they are capable of taking down animals more than double their size and larger hunts will provide them with food for many more days (Baker 2006). Tigers have been seen hunting at all times of the day and night, and their activity patterns are mostly dictated by the sleep/activity patterns of their major prey species (Baker 2006). Tigers silently stalk their prey, usually from within 9 and 21m, using their dark stripes as camouflage through dense cover (Baker 2006). Tigers employ a variety of behaviours in order to reduce their chance of being detected, including crouching down low to increase camouflage, freezing for long periods of time should their prey become wary, and almost always choosing to approach their prey from downwind (Baker 2006). Furthermore, tigers may even chase their prey down into the water in order to increase their chances of making a successful kill (Baker 2006). Tigers will charge at their prey unexpectedly from behind (Tilson 2016). Small prey items are usually easily killed by biting the animal on the neck, however larger prey items are latched onto by the tiger and, using their jaw and forearms, they drag the prey to the ground. Once the prey has been brought to the ground, the tiger then grabs the animals throat and holds on until it suffocates (Tilson 2016). Tigers will feed on large carcasses across several days until it is fully consumed, but are capable of gorging themselves on as much as 20-30kg of meat in one sitting (Tilson 2016). 3.7 SOCIAL BEAHVIOUR AND GROUPINGS Tigers are solitary, meaning they live and hunt alone (Tilson 2016), and each adult Siberian tiger (usually 3 years and older) must have its own home range in order to successfully survive and reproduce (Tian et al. 2011; Tilson 2016). The estimated home range for each individual is thought to be between 120 and 565 km² (Hernandez-Blanco et al. 2015; Miquelle and Rozhnov et al. 2015), with an average of between 360 and 445km² (Tian et al. 2011). Furthermore, Siberian tiger males will often have home ranges that overlap the home ranges of either one, but usually two, or more female Siberian tigers, making them a ‘sex-specific territorial’ species (Hernandez-Blanco et al. 2015). Male home ranges, however, will usually not allow any overlapping territory with other males and therefore maintain exclusive breeding rights with any females inside his home range (Tilson 2016). Interestingly, the size of an individual’s home range is thought to be mainly influenced by the abundance of its food source and therefore home ranges are estimated to be much larger in areas where food is scarce (such as Siberian tiger habitats), compared to when the food source is in abundance (Baker 2006). As tigers live in an interlinked social system it is not uncommon for them to encounter each other during travel and may sometimes (though very rarely) even share a large kill (Baker 2006). Usually, however, their preference for a solitary lifestyle is maintained via means of vocalisations as well as visual and scent markers and individuals will usually only meet up each breeding season, for mating purposes (Baker 2006). Therefore, the only long-term interaction that is ever demonstrated within Siberian tigers is between mothers and her cubs, which can include day-to-day interaction for up to two years (Baker 2006). The type of visual and scent marks often used by Siberian tigers includes, urine sprayed on trees and bushes or left in prominent areas often travelled by neighbouring individuals, as well as scattered faeces, scrapes on the ground or scratch marks in trees (Tilson 2016). Scent and visual markers are redone regularly and can be used to also help males determine when a female is in oestrus and therefore ready for mating (Tilson 2016). 3.8 NATURAL PREDATORS AND DISEASE PREDATION With the exception of humans, Siberian tigers do not have any natural predators. However, conflict between humans and Siberian tigers is considered to be the worst of all the tiger sub-species, with more humans being killed annually by Siberian tigers than any other subspecies (Goodrich et al. 2011). Currently, throughout the entire remaining range of Siberian tigers there are humans and conflict with the species can often result in the loss of human livelihood, when tigers kill their domestic livestock, or loss of human life (Goodrich et al. 2011). These losses lead to negative attitudes towards tigers, and any attempted tiger conservation, as well as retaliatory killings and increased levels of poaching (Goodrich et al. 2011; Mukhacheva, Derugina, Maksimova and Soutyrina 2015). Although this conflict has been significantly reduced over the past century, mainly due to the significant decline in Siberian tiger population numbers, human-tiger conflict almost always leads to increased Siberian tiger mortality (Goodrich et al. 2011). This mortality can be caused by humans either directly, via poaching or retaliatory killings, or indirectly via means of prey loss, habitat degradation, fragmentation or loss as a result of logging or the construction of roads, buildings and/or agriculture (Tian et al. 2011; Alasaad et al. 2011; Robinson, Goodrich, Miquelle, Miller and Seryodkin 2015). In order to decrease tiger mortality, and therefore increase population numbers, significant effort must be taken to change the attitudes of humans in which share their habitat. DISEASE In aged, captive tigers, respiratory kidney and liver diseases often cause significant problems. Furthermore, Siberian tigers are capable of carrying and catching a variety of diseases including, bacterial, viral and parasitic (Williams and Throne 1996). Bacterial: Bovine Tuberculosis (TB) has been known to occur in Siberian tigers and is most often contracted via contaminated meat and/or offal (Williams and Throne 1996). This disease effects the animal’s lungs and is long-lasting and often difficult to treat (Tilson 2016). Bacillus anthracis causes Anthrax and has been found to lead to fatalities in large captive felids, such as tigers. This disease is capable of causing death to the animal in a little as 1-4 days and is known to cause blood clots in the animal’s spleen (Tilson 2016). Much like, Tuberculosis, Anthrax is most often contracted via exposure to a contaminated food source (Williams and Throne 1996). Other bacterial diseases have been reported such as: bacterial meningitis, Clostridium, Colisepticemia, Corynebacterium pyogenes, Perfingens, Salmonella spp. and Shigella flexaeri, all of which effect the body’s ability to either transport oxygen to or carbon dioxide from the lungs (systemic diseases) (Tilson 2016). - Salmonella spp. have been known to cause issues for both tiger cubs and adults and, if contracted, can cause symptoms ranging from mild gastrointestinal upset to fatalities (Tilson 2016). Thankfully, good quality control of their food source in captivity is an effective way of reducing the chances of infection from such bacteria (Tilson 2016). Parasitic: Large, wild felids are capable of contracting parasites such as Trichinella spiralis and Toxoplasma gondii, however most cestode parasites are not harmful to the large felid species that carry them but may be harmful to other species that are capable of catching it (Williams and Throne 1996). For instance, felids have been found to carry the parasite Echiococcus multicularis which does not cause them any significant illness, but if contracted and left untreated in humans has been known to result in fatalities (Williams and Throne 1996). Furthermore, the parasite Microsporus canis has been known to effect tiger cubs and cause hairloss, luckily it is easily treated (Tilson 2016). Viral: Large felids, such as tigers, are capable of contracting a variety of viral illnesses such as pseudorabies and respiratory illnesses including feline rhinotracheitis, panleukopenia, feline infectious deritonitis and feline calicivirus (Williams and Throne 1996; Tilson 2016). Such viruses however, are considered mild and result only in rash (pseudorabies), have vaccinations that are proven effective for both domestic and wild feline species (rhinotracheitis and clicivirus) or have low mortality rates if contracted (Williams and Throne 1996; Tilson 2016). One other viral disease, however, has been recently considered as a serious pathogen and is capable of being contracted by a variety of wild feline species, such as lions, leopards and tigers (Nagao 2012). This virus is known as the Canine Distemper Virus (CDV) and has been found to result in a number of Siberian and Bengal tiger deaths in captivity (and the wild) since 1983 (Williams and Throne 1996). CDV is within the Morbillivirus genus, has a single stranded RNA genome and is caused by a Paramyxovirus (Nagao 2012; Gilbert et al. 2014). This virus primarily infects the alveolar macrophages within the lungs, before spreading throughout the lymphatic system and is transmitted mainly during close contact with contaminated individuals through the respiratory tract (Gilbert et al. 2015). However, transmission via contaminated urine or faeces has also been demonstrated (Gilbert et al. 2015). CDV has been shown to cause a variety of symptoms including: fever and laboured breathing, nasal discharge, diarrhea, anorexia and dehydration, all of which occur in the early stages of contraction (Tilson 2016; Gilbert et al. 2015; Nagao 2012). However, once progressed more serious symptoms such as behavioural changes (with some becoming unafraid of humans), muscle twitches and even seizures have been demonstrated (Tilson 2016; Gilbert et al. 2015; Nagao 2012). Unfortunately, once contracted the outcome is often fatal (Nagao 2012), with many animals dying during the initial stages of the spread or relapsing in the future should they be lucky enough to survive the first time (Tilson 2016; Gilbert et al. 2015). Evidence from captive individuals has shown that the virus can lie dormant in the body, after the initial contamination, for as many as 150 days (Gilbert et al. 2015). Many of the diseases listed above including, TB, Rabies, Anthrax and Salmonella spp. are known zoonoses and therefore are capable of being passed from human to tiger, and visa versa. All precautions should be taken to ensure that such diseases, should they be contracted, are not passed between individuals or species (Tilson 2016; Nagao 2012). 3.9 THREAT TO HUMAN SAFETY Historically, tigers have been known to kill and injure large numbers of people and as a result are often regarded as one of the most likely species, all of the large felids, to be involved in conflicts with humans (Goodrich et al. 2011). Unfortunately, at present humantiger conflict still exists and is thought to occur everywhere the two species co-exist, with attacks on humans occurring annually (Goodrich et al. 2011). However, due to the encroachment of human populations into tiger territories many of these killings are likely to be due to tigers attempting to protecting their cubs (or themselves) from poaching or retaliatory killings from humans when tiger prey gets low and they are forced to hunt domestic livestock. It is a widely believed view that once tigers have a taste for human flesh, they are likely to begin actively hunting them as a source of prey (Baker 2006). However, tigers do not normally view humans as prey and only in extreme circumstances will tigers actively hunt humans for food (Baker 2006). Such circumstances include, when the tiger is old, sick or injured and therefore is no longer able to catch its natural prey source (Baker 2006). Therefore, assuming the highly unlikely event that a Siberian tiger should be loose in Tasmania human safety could be compromised. However, a captive tiger that has never encountered human flesh before is only likely to attack should it become startled or feel threatened. 3.10 HISTORY AS A PEST Siberian tigers are not currently considered as a pest species. Furthermore, they have not been known to establish feral (non-native) populations outside of their native range and are not recorded on the Global Invasive Species Database (Global Invasive Species Database 2015). To date, no introduction attempts have been noted. However, Siberian tigers are capable of impacting agriculture as it is known that when their natural prey source becomes scarce (usually through overhunting of their prey by humans) Siberian tigers will turn to hunting domestic livestock as a source of prey (Robinson et al. 2015). 3.11 POTENTIAL IMPACT IN TASMANIA Siberian tigers would likely consume native wildlife, such as Bennetts wallabies (Macropus rufogriseus), Paedemelons (Thylogale billardierii) and potentially even Tasmanian devils (Sarcophilus harrisii), but would happily eat any prey item that it came across, potentially decimating native populations. However, since Tasmania’s native species are small compared to the sorts of prey consumed by Siberian tigers in the wild, it is likely that domestic livestock such as sheep and cattle would become the major source of prey for Siberian tigers in Tasmania. Ramifications from this would of course result in the loss of livelihood for farmers and the potential for the loss of human life should any human-tiger conflict arise as a result of tigers hunting livestock. However, in the extremely unlikely event that a Siberian tiger should find itself free in the Tasmanian ecosystem, their infrequency to ovulate, paired with the very short time they are fertile, plus their wild mortality rate and the length of time for cubs to become independent and reach sexual maturity would all contribute to making it extremely unlikely to establish a feral population, Furthermore, their size, the public uproar and the damage they would cause from feeding on livestock, as we have no other large carnivores in the state, would therefore make them easily trackable. Additionally, climate modelling shows that Tasmania’s climate is unsuitable for the continued survival of Siberian tigers. Therefore, establishment of this species is severely unlikely. 4. RISK ASSESSMENT 4.1 PREVIOUS RISK ASSESSMENT The Siberian Tiger has previously been assessed by the Commonwealth Vertebrate Pest Committee (VPC 2007) as an ‘extreme’ risk. Therefore, under this VPC classification Siberian tigers may only be kept by those who hold a permit for education, conservation, entertainment and/or exhibition (VPC 2007). In Tasmania, the Siberian tiger would likely be considered a ‘controlled animal’ under the Nature Conservation Act 2002, however, the Siberian tiger has not yet been considered for importation into Tasmania. 5. REFERENCES Alasaad, S., Soriguer, R.C., Chelomina, G., Petrovich Sushitsky, Y. & Fickel, J. (2011). Siberian tiger’s recent population bottleneck in the Russian Far East revealed by microsatellite markers. Mammalian Biology 76 (6). P. 722-726. Baker, R. (2006). The tiger Panthera tigris. 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