Thursday, October 14, 2010
Discussion Question 5 (Primary Threats)
Learn about a well known endangered species, such as the koala bear, the right whale, or the cheetah. Why are these particular species vulnerable to extinction? Use the IUCN criteria (IUCN 2001) to determine the appropriate conservation category for one or more species.
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African elephants, Loxodonta africana, are the largest terrestrial animals on earth. The species is separated into two subgroups, the African bush elephant and the African forest elephant. Though there are a few causes such as habitat cleared for settlement and farming, drought, trophy hunting, and some villages killing them because they’re thought of as pests, that may contribute to their endangerment, the most prevalent reason leading to their endangerment is poaching. Though the main reason for the mass killing of African elephants is to obtain their valuable ivory tusks, they are also killed for what is known as bush meat. The endangerment of the African elephant is one specific case where a species is endangered not necessarily because of natural causes or habitat degradation, but because of direct human interference through poaching.
According to the IUCN, as of 2004, African elephants are classified as a vulnerable species, though they were previously classified as endangered in 1996. Their specific classification is due to direct observation of “population size reduction of ≥ 30% over the last 10 years or three generations, where the reduction or its causes may not have ceased” (IUCN). Though their population is believed to be gradually increasing, African elephants are still considered vulnerable because poaching and degradation of their habitat has not subsided. Additionally, population estimates for the African elephant are hard to acquire because of their large range of distribution and numerous habitat variations. There are also no credible estimations of their population prior to the late 1970’s, so it is difficult to make comparisons to the past.
Furthermore, though CITES, the Convention on International Trade in Endangered Species, banned the trade of ivory in 1989, poaching elephants for their tusks is still a very prevalent problem today. According to “Elephant populations and CITES trade resolutions,” there is a commonly used loophole in the illegal ivory trade, where people claim that their ivory is pre-ban ivory. Because ivory obtained prior to the 1989 ban is still legal to trade, many people claim that their ivory is pre-ban in order to illegally sell it. Moreover, though the population of African elephants may be increasing gradually, it is clear that until poaching is stopped or at least greatly reduced, African elephants will continue to be a species vulnerable to endangerment.
References
Blanc, J. "Loxodonta Africana." (African Elephant). IUCN Red List of Threatened Species, 2008. Web. 16 Oct. 2012. www.iucnredlist.org/details/12392/0.
Van Aarde, Rudi J., and Sam M. Ferreira. "Elephant Populations and CITES Trade Resolutions." Environmental Conservation 36.1 (2009): 8-10. Web. 16 Oct. 2012.
http://repository.up.ac.za/bitstream/handle/2263/13646/VanAarde_Elephant%282009%29.pdf?sequence=1.
Hector's Dolphin, also known as the New Zealand Dolphin or White-Headed Dolphin, is the best known species of the genus, yet it was listed as endangered by the ICUN in 2000 due to a rapid decline in population size over the past 30 years.
This species is endemic to New Zealand, meaning that it is found only off the coast of New Zealand and nowhere else. Here, the species consists of four distinct subpopulations, three off of the South Island and one off of the North Island. Through DNA studies, researchers have found that the population living in the North is genetically distinct from those in the South. This indicates that there is no gene flow between the populations in North and the South.
In addition to this lack of gene flow, this species is particularly sensitive to population decline because of its very restricted habitat. Hector's dolphin lives in shallow coastal waters, less than 15km from shore and in water less than 100m deep where they feed on several species of small fish and some squid.
Unfortunately, this habitat is also extensively exploited by humans who fish the area. This is dangerous for the dolphins because they become entangled in the fishing nets of mostly amateur fishermen. In fact, 60% of Hector's dolphin deaths are from entanglement in gill nets, which are the more popular form of fishing net in the area. Secondary threats to the species include pollution, disease, vessel traffic, and habitat modification.
Because of the serious population decline occurring off the New Zealand coastline, the national government has taken measures to reduce the mortality of the species. As of today, there are two protected areas covering Hector's dolphin habitat. These protected areas have been somewhat successful in that there has been a reduction in Hector's dolphin mortality, but this is not enough to return the population to stability. Analysis shows that mortality must be reduced to zero if the species is to recover. Therefore, the department of conservation and the ministry of fisheries are working together to "develop a more comprehensive management plan."
CITATION:
Reeves, R.R., Dawson, S.M., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2008. Cephalorhynchus hectori. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . Downloaded on 22 October 2012.
The Snow Leopard (Panthera uncia) is an endearing species that lives high up in the mountains of Central Asia. These animals are extremely reclusive and solitary, which makes them very difficult to track. Their current range is mostly unknown at this point because of their elusive nature, but it has diminished greatly over recent years. This decline in territory has caused their numbers to plummet and has caused the IUCN to place them on the “red list” of endangered species. Their numbers currently are between 4,080 and 6,590 mature individuals, although their effective population size is less than half of that.
However, habitat loss is not the only, or even the foremost, cause of the big cats’ demise. Conflicts with the local people are becoming more frequent and are the most detrimental. Snow leopards prey mostly upon wild sheep called blue sheep or bharal, and also on ibex. They occasionally go after smaller mammals such as marmots or pikas, but they prefer larger animals. Unfortunately, the bharal (and the ibex too, to some extent) compete for resources with the domesticated livestock, and as a result they are exterminated. This causes the leopards to turn to the domestic animals for food, and thus they too are killed. Other struggles include illegal trading of snow leopards on the black market. The hides and bones of these animals are prized by some countries for medicinal reasons, and consequently they are killed by locals.
Lastly, lack of effective law enforcement is a major problem. There are a substantial amount of regulations attempting to protect these majestic creatures, but there are not enough people to make sure the laws are carried through. And, as in many areas, lack of knowledge and awareness is always a problem. Many conservationists are working to give the local people a greater education and better means to protect their native big cat. Hopefully this will pay off in the future.
Citation: Jackson, R., Mallon, D., McCarthy, T., Chundaway, R.A. & Habib, B. 2008. Panthera uncia. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . Downloaded on 23 October 2012.
The Red Wolf (Canis Rufus) is an endangered species that had gone extinct in 1980, but was reintroduced to North Carolina by 1987. There are now about less than 150 individuals of which 50 are mature adults. The species occurring outside this reintroduced area is unknown. Their historical distribution was believe to be only in southern eastern parts of the United States, but later other discoveries described their range to reach through Pennsylvania and extend to the most eastern parts of Canada. Their habitat and ecology is very little known because there was a severe reduction of their habitat range by the time scientific investigations began.
When observing the reintroduced population of the red wolf in North Carolina and their descendants, researchers noticed that they were not too habitat specific as long as they had habitats that ranged from agriculture and/or forest/wetlands and that these environments had adequate prey populations and minimal human disturbance and persecution.
Although human generated deaths were significant among the red wolf population that was reintroduced (gunshots, vehicles, etc.), the main threat to the species is the hybridization with wild coyotes. This was detected in 1999 and a management plan was designed to keep the hybridization rate low to sustain the red wolf population. Many would argue that the red wolf is actually already a genetic combination of the red wolf and coyote so this is still a controversial issue whether the red wolf should still listed on the endangered species list.
Citation: Kelly, B.T., Beyer, A. & Phillips, M.K. 2008. Canis rufus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . Downloaded on 26 October 2012.
The Red Wolf (Canis Rufus) is an endangered species that had gone extinct in 1980, but was reintroduced to North Carolina by 1987. There are now about less than 150 individuals of which 50 are mature adults. The species occurring outside this reintroduced area is unknown. Their historical distribution was believe to be only in southern eastern parts of the United States, but later other discoveries described their range to reach through Pennsylvania and extend to the most eastern parts of Canada. Their habitat and ecology is very little known because there was a severe reduction of their habitat range by the time scientific investigations began.
When observing the reintroduced population of the red wolf in North Carolina and their descendants, researchers noticed that they were not too habitat specific as long as they had habitats that ranged from agriculture and/or forest/wetlands and that these environments had adequate prey populations and minimal human disturbance and persecution.
Although human generated deaths were significant among the red wolf population that was reintroduced (gunshots, vehicles, etc.), the main threat to the species is the hybridization with wild coyotes. This was detected in 1999 and a management plan was designed to keep the hybridization rate low to sustain the red wolf population. Many would argue that the red wolf is actually already a genetic combination of the red wolf and coyote so this is still a controversial issue whether the red wolf should still listed on the endangered species list.
Citation: Kelly, B.T., Beyer, A. & Phillips, M.K. 2008. Canis rufus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . Downloaded on 26 October 2012.
The Tasmanian Devil (Sarcophilus harrisii) is endemic to Australia. In 2008 the IUCN Red list classified this species as endangered due to the rapid decline in the population over the past ten years. There are two genetically distinct Tasmanian Devils that have been identified, North-western and Eastern/South-western. Their genetic diversity is low due to the island founder effect and low population size. Having low genetic diversity could potentially reduce population viability but also the resistance to diseases. The major threat that is affecting the devil population is an infectious disease called Devil Facial Tumor Disease. Devil facial tumor disease has declined the devil population by about 89% since the disease was first reported; these results were confirmed through trapping and lab results. This disease targets the older adults of the population and then the younger adults. Some females might not even be successful in raising a litter before they die of devil facial tumor disease. So far the mode of transmission of devil facial tumor disease is not yet known.
In addition to the disease the devil population has been decreasing by being killed by dogs or hit by vehicles. From a study about 2,205 Tasmanian Devils were killed on the road annually over a three-year period. As of 2003 the Department of Primary Industries and Water started a program called Tasmanian Devil Disease Program to investigate and respond to Devil Facial Tumor Disease. There is also research being conducted to discover a vaccine to treat this disease but the process is expected to take many years. As of right now about forty percent of the state of Tasmania is protected but this may not stop devil disease from occurring. Much more information is required in order to save this species.
Citation: Hawkins, C.E., McCallum, H., Mooney, N., Jones, M. & Holdsworth, M. 2008. Sarcophilus harrisii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . Downloaded on 25 October 2012.
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