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Abstract: This essay discusses about the causes of animal extinction. Animals are sidestepped as we tend to focus more on something that happens to our brethren. However, we also forget that what happen to our species, the human beings, it affects the animals and plants more, as they don't have the ability to think and manipulate the environment as skilfully as we do. Habitat destruction, uncontrolled hunting and trading spreading of diseases, and drastically changing climates are among the prominent causes of animal extinction. We are exposed to what animals are endangered, we are exposed to how we can conserve them, but we have yet to be exposed to what causes the extinctions, which will roll the ball for further research on how to prevent them. This would be useful, as prevention is always better than cure.
Animals are part of our ecosystem, not only they contribute to the ecosystem and help to balance the ecosystem, they also have many uses in our daily lives, as the source of nutrition, researches, pets and trading. But due to human's greediness, selfishness and also expand in populations, caused the population of the animals to decrease up to the point that they are in danger and eventually disappear from the surface of Earth like Dodo bird and Tasmanian Tiger. Yet, this issue is ignored or sidestepped as we care more of what affect us directly, when we should know that sooner or later, as part of the mammal species, these phenomena will also happen to us. Habitat fragmentation, destruction or loss, unsustainable hunting and wildlife trade, global warming and disease are the factors that lead to animal extinction.
One of the main factor of animal extinction is habitat fragmentation, loss or in another word habitat loss. Research had been carried out by Bancroft and Turchin in year 2003, using a series of experiment with grain beetles, Oryzaephilus surinamensis proved that "6% out of 247 populations went extinction"  when they carried out the experiment on the relationship between "habitat fragmentation and decreasing food abundance"  and the result shown that these grain beetles went to extinction due to low food supplies. This result gives a suggestion that" habitat quality is more important than the habitat size itself". Not only are that, another study that was carried out by Warren, another researcher, who does research on 13 types of protists in 1996  by applying three levels of habitat destruction of microcosm. As the result, the population of the surviving species greatly declined due to the rising in habitat destruction. As we know, Tropical Rainforest  consisted of many precious trees that used as the materials in industrial purpose. Not only for industrial uses, but also as the habitat for variety of species. Due to the huge demand by various parties, more trees had to be cut down to satisfy the demand of the parties. As the result, that inhabitant's population begin to decrease as there's not enough place to live and hunt. If this is prolonged, the animal's species will go extinct.
Unsustainable Hunting and Wildlife Trade
Another factor that contributes to animal extinction is unsustainable hunting and wildlife trade. This happened in many countries across the world. Many animals were hunted to extinction when the aboriginal Europeans, Americans and Australians developed the "effective hunting technology"  . One such animals were hunted to extinction by this is the Dodo birds. Certain bird such as the Eskimo curlew went extinct when they were "relentlessly hunted by the market gunners during their migration". Some animals were caught for pet trade such as orang utan. These animals are considered exotic and were sold to the people that are interested in this kind of wildlife animal and were willing to pay for it. "In one of the most outrageous cases of simultaneous drug and wildlife smuggling which occurred at Miami Airport in 1993, 312 boa constrictors that arrived from Colombia were found carrying inside them 39 kilos of cocaine. All of the snakes eventually died"  â€¦ Shows that wildlife not only kept as pet but also for drug trading purpose. Animal such as leopards, jaguar and Guadalupe fur seal were highly favoured for their beautiful furs was hunted to get their pelts and the same goes to tigers where poacher killed them for their body parts which are used in "traditional medicine and aphrodisiacs"  . Not only tiger was hunted for this purpose, but rhinoceros and elephants too, were hunted for their tusks. All these items were sold for high price in black market. "Commercial whaling for their meat and oils"  had threatened the most of the Baleen whale and several toothed whales species in the world. Whale's meat is popular among the Japanese and it's one of their favourite dishes, thus in order to meet the demands in Japan, every year whales was hunted during whaling season. Primates are often captured for research purpose especially in well developed country. They are trade to the biomedical lab with certain price and this biomedical lab will use them as research in finding cure for certain disease. An example of primates that often used in this field is chimpanzees. Even though they are not yet extinct, but they are classified as the endangered species because they are not only used in research but also become the target of the bushmeat hunter.
The third factor would be global warming. Mother Earth and its residence depend on the seasons for their routines and timings. Mating season, migration, all of it due to the weather. With global warming, the timing of seasons is changing. Some are longer than expected, some are shorter than hoped. This bungled the biological clock of animals that are already accustomed to instinct-based timing and activities. While it seems nothing to us humans, it is consequential towards animals and plants.
Migration accelerates.( will expand later)
Dehydration, combined with the rapidly vanquishing habitats, causes certain species to vanish.(will expand later)
Stuart Pimm, an expert in extinctions and biodiversity at Duke University in Durham, North Carolina stated that species living in the ecological sites are more vulnerable, as they don't have much choices of places to migrate to when the temperate changes  . It is interesting to note that not as expected, the animals living at the polar (North Pole and South Pole) is not as vulnerable as the animals living in other climates, though the poles have experienced seen differences. That is because of the scarce geographical places the endangered species can run to is smaller than them.
Dangerously, not only animals in endangered spots that are facing the fatalities. According to biologist Terry Root, of Stanford University's Center for Environmental Science and Policy, many species are striving to hold on to their current locations. 
There are two groups of diseases: natural occurrence, which is formed since a very long time and unpreventable, and the other one would be human-induced or mutated. Both would give dire consequences on the species affected, especially in masses.
Among the example of human-induced diseases are effects of insecticides. Insecticides are regarded as a low-level dangerous substance, as they tend to prevent high crops loss. However, it also forced pests and infections to evolve. Once evolve, we would need a higher dose of insecticides. In the end, the effects of insecticides in plants will affect the animals that eat them too.
Besides that, there are effects that happen not to the animal directly, but towards the next generation. A hen may lay eggs with thinner and fragile eggshells. This, while seem minor, could actually cause a higher risk of survival. In the long run, extinction would not be far in the future of the species. This really did happen. One insecticide, DDT, caused the eagle and peregrine to produce eggs with fragile eggshells, causing the eggs to break when the mother sit on them  . How can they be incubated without the mother warming the eggs? How can the mother incubate the eggs without sitting on them, yet when it sits, they will break? These are among the complexities that we don't comprehend or didn't put into the equation when we create the insecticide.
Too much protection would also be unhealthy. When a species is protected from risks and diseases up to a paranoid level, it causes them to have lower and lower immunity to their offspring. This causes them to be weak and unable to sustain injuries and total fatalities if they ever catch any infections.
Lastly under the factor of diseases, are the effects of genetic evolution. While it was not the total annihilation of species, it is still, in a sense, the cause of species extinction, happening due to the chances of survival with the enhanced or reduced ability. Perhaps a smaller or robust body is better adapting during this period of time, whereas speed and agility is more vital during the past. This theory applies to the birds, where during prehistoric times; birds have wider scales of bones while they have smaller lighter body now. Habitat, food consumption, and brain metabolism, all contribute towards genetic evolution, causes the extinction of the older type of species in exchange for a better, new species.
Thus, it is supported that the evidently seen causes are habitat loss, unsustainable hunting and trading of wildlife, global warming, and finally, infectious diseases. Two of it in which we contributed a lot in making it much worse, and two of the latter in which we have taken part albeit indirectly.
Although a little out-dated, this research still hold a whole lot of truth. It is hard to fund more of these kind of research, as we humans are more interested in studying further of subjects that brings more material benefits instead of invisible threats. We are keener on studying on the psychology of potential customers, convenient products, and less consumption of resources. These researches are conducted with good intentions, but obsession of a narrow topic makes us putting a blind eye over other things that matter too, namely, other creatures co-existing with us. Some of the references here were spoken on 2006. Now, it's 2011. In the span of 5 years, how much have we lose, can you imagine?