Australia’s Endangered Animals (Tasmanian Devil)
Australia’s Endangered Animals (Tasmanian Devil)
The most basic definition of biodiversity is well presented by Takacs (1996) as the fullness of variety on the earth in regard to life. This aspect of nature studies the processes necessary for the creation and maintenance of the said variation. The main concerns under the subject include the assortment of individuals living in populations, diversity of species in communities and the range of ecological roles played within ecosystems (Quebec Biodiversity Website, n.d.). According to Chadwick (1993) the wide scope intimated in the said definition has resulted in a section of scholars replacing the term biodiversity with wilderness of nature. With respect to the theory of biodiversity, there are three accepted levels of analysis: genetic, species and ecosystem diversity. Species diversity is the area that attracts most focus simply because species are relatively simpler to identify in the field using the naked human eye. Genetic diversity requires laboratory equipment and time, among other resources, while ecosystem diversity demands complex measurements spanning significant periods of time.
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The second element of the biodiversity theory is gain and loss. It discussion starts with E.O. Wilson’s and R. MacArthur’s neutral theory of island biogeography, which posits the equality of all species. Species on larger islands face a higher vulnerability to extinction, as do those travelling a longer distance from the ‘mainland’. The parameters employed in the measurement of diversity are difference, evenness and numbers. The phenomena responsible for gains are mutation, speciation, immigration and succession, while those attributed to loss are extinction, completion, disturbances and bottlenecks. The theory of biodiversity necessarily tackles abundance and composition. The existence of variable species is testament to the fact that no species is perfect in all facets; none can therefore outcompete and consequently eliminate the others. Trade-offs with respect to certain liabilities has given rise to the abundance nature proudly presents. Chance, catastrophes, keystone species, niches and variable environments elucidate this aspect. The final level of the biodiversity theory is the ecosystem functioning, vis-à-vis stability. The crux of this area is how components like energy and certain species change with time. The salient question is whether diversity leads to stability (Bernhardt, n.d.).
With the outline of the biodiversity theory put in place, the stage is set for the discussion of the endangered animals. Australia is arguably one of the most diverse nations worldwide. Over a million species of animals and plants call the place home. Moreover, many of these species cannot be found anywhere else (Department of the Environment, Water, Heritage and the Arts, 2009). The term endangered species refers to species of an animal in the wild, whose total population is dangerously low, flirting with extinction. For vulnerable species, although the risk exists, it is lower than the case of endangered species. The sad reality is that Australia’s Sarcophilus harrrisii, commonly known as the Tasmanian devil, faces the threat of extinction. The placement of this animal on various endangered species lists was an acknowledgment of the said threat and more importantly, an opportunity to work at sustaining the lives of the remaining individuals and allowing further procreation in a protected environment. The variable claiming greatest responsibility for the dwindling numbers of the Tasmanian devil is the Devil Facial Tumour Disease (DFTD). The tumours that develop around the Devils’ mouths hinder them from feeding, leading to death as a consequence of starvation. In addition to this, females lose their young, curtailing the perpetuation of their progeny. This takes about six months. A population drop from 150,000 in the 90s to anything between 20,000 and 50,000 in 2006 is certainly alarming. The fact that it is one of only two communicable cancers makes the problem that much harder to address (Hansford, 2008).
The Tasmanian devil is the largest of the surviving carnivorous marsupials. It is characterized by its thickset build, broad, relatively large head and thick, short tail. More often than not, the fur is wholly black in colour, but there may be white markings on the chest as well as the rump. Body size varies, based on a mixture of habitat and diet. Normally, adult males are larger than females, weighing between and 10 and 12kg while the latter weigh in at 6 to 8 kg. On average, the Tasmanian devil stands at a shoulder height of 1 foot. The Devil’s famed threatening yawn can sometimes be misleading as it may indicate uncertainty and fear, rather than aggression. In fact, when stress levels are significantly high, they release a pungent order to scare off threats. This nocturnal scavenger feeds on anything that crosses its path. Sharp, strong teeth and powerful jaws allow it to devour prey completely, fur, bones and all. Wallabies, birds and small animals are consumed either as prey or carrion. Insects, amphibians, reptiles and on occasion sea squirts are other items on the Tasmanian devil’s diet. In settlement areas, cattle and sheep carcasses fulfil the Devil’s food requirements. As Devils clean up carcasses, they reduce instances of blowfly since maggots are left without food. The noise and rowdiness emanating from their communal feeding are simply ways of establishing pack dominance. The fierce noises these animals usually make range from harsh snarls and coughs to screeches of very high pitch. Sharp sneezes indicate a challenge to rival devils and are commonplace before physical encounters. However, most of these behaviours serve as bluffs, intended to reduce harmful confrontations at feeding time. Devils are actually shy, wary creatures.
Based on anecdotal evidence, the Devil’s population has been variable over the last 100 years, registering historic highs in the 90s. They have a preference for woodlands, forests and the agricultural parts of central, eastern and northern Tasmania. 1996 signalled the start of the population decline, owing to DFTD, as discussed elsewhere in this paper. Statistics indicate that stated condition is responsible for the 70% decrease in instances of spotlighting sightings. Looking at the State’s north eastern corridor, where DFTD was first noticed, the approximate decrease in sightings is 95%. Another study draws attention to the absence of the Devil in the mainland to the coincident introduction of dingoes by Aborigines (DPIW, 2008).
Fig. 1: Map indicating the distribution of the Tasmanian, along with the spread of Devil Facial Tumour Disease (DPIW, 2008)
With respect to habitat, Tasmanian Devils can be found all anywhere from the coast all the way to the mountain ranger. They are not picky, living comfortably in sclerophyll rainforest (open, dry or mixed) and coastal heath. In essence, they are happy in any place they can hide during daytime and food during the night (DPIW, 2008).
Threats to Survival
Apart from the massive threat of DFTD already dissected, other factors threatening the survival of Tasmanian devil are road-kill and the red fox. Red foxes prey on devil juveniles, thought the threat has not reached significant proportions. Competition amongst themselves, direct persecution, the loss of valuable den sites to human purposes and attacks by quolls and thylacines are other factors that control their numbers. Assessing road-kill statistics obtained in the year 2008, 13 devils were killed over an 11 mile stretch in the period between January and April (DPIW, 2008).
The spread and impact of DFTD has necessitated a significant degree of human intervention. Physical separation is indeed the only method of adequately separating infected devils from healthy individuals. It must also be noted that human beings cannot contract DFTD, making them suitable agents of devil survival. Initiatives like ‘Save the Tasmanian Devil’ have contributed to this end, along with the widespread dissemination of information regarding the species. Intensive research relating to DFTD is an important concern, analysing the disease as well as management options. Moreover, captivity allows for a longer life expectancy, compared to the five years in the wild. Simple acts like moving dead wallabies from roads to paddocks significantly reduce devil mortality rates (DPIW, 2008).
The study of the Tasmanian devil shows the effect of natural factors and human intervention, positive or otherwise on biodiversity. Devils play an important role in balancing the ecosystem. They regulate the population of predators like feral cats and foxes. Head of WWF (World Wildlife Federation) Australia, Ray Nias, captures this when he says that an increase in cats and foxes would eliminate several mammalian species unique to the area of Tasmania (Davidson, 2008). The first necessary step is to establish the actual population of the devils to paint an accurate picture of the status quo. This information will present a workable baseline for further assessment with respect to aggressiveness necessary for fruitful containment. A rigorous awareness campaign, further study on the disease and effective implantation of measures like using remote sensor cameras for monitoring purposes will prove vital. There is no doubt that heavy economic investment in necessary. This is where collaboration close collaboration among all stakeholders, the public included, comes in. Every contribution counts. The use of certain chemicals must also be eliminated altogether as they may be responsible for the cancer; devils come into contact with them as they scavenge for food (Davidson, 2008). Attending to these measures with the necessary urgency will stem the decline in population of the species. The Tasmanian devil subject is indeed a powerful statement that requires utmost attention.
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Davidson, LL 2008. Tasmanian devil Endangered. Retrieved on 30th March, 2009, <http://www2.scholastic.com/browse/article.jsp?id=3749635>
Department of the Environment, Water, Heritage and the Arts 2009. Sarcophilus harrisii – Tasmanian Devil. Viewed 30th March, 2009, <http://www.environment.gov.au/cgibin/sprat/public/publicspecies.pl?taxon_id= 299>.
DPIW (Department of Primary Industries and Water) 2009. About Tasmanian Devils. Viewed 30th March, 2009, <http://www.dpiw.tas.gov.au/inter.nsf/WebPages/BHAN- 5358KH?open>.
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Hoax, T 2009. Facial cancer could wipe out Tasmanian Devil population. Retrieved on 30th March, 2009, <http://www.examiner.com/x-2430-Science Examiner~y2009m1d25Facial-cancer-could-wipe-out-Tasmanian-Devil-population>.
Quebec Biodiversity Website n.d. Biodiversity Theory, Viewed 31st March, 2009, from <http://canadianbiodiversity.mcgill.ca/english/theory/index.htm>.