Biology

A species is a taxonomic group of organisms whose members can interbreed and is said to be at risk, threatened or endangered when it faces of extinction such that its numbers are dangerously low to the extent that its gene pool diversity is affected. In history, extinction of species has been attributed to natural causes but recently, human activity has been the greatest contributor to extinction. In 2007, The International Union for Conservation of Nature (IUCN) red list contained more than 40,000 species and about 16,306 facing possible extinction (The Environmental Literacy Council, 2008).

In the United States, the 2007 IUCN red list contained about 1,351 endangered plants and animals (The Environmental Literacy Council, 2008). Due to the threatening danger of extinction of species, the government was forced to provide institutions and legislation to protect the endangered species. One of these legislations is the endangered species act (ESA). This act requires that during listing of a species as endangered, there should be designation of specific areas occupied by the endangered species. These areas are reffered to as critical habitats. The table below gives statistics of species listed as endangered and candidates listed for critical habitats.

Table.1
Description PlantAnimal Endangered or threatened796618Proposed for listing as endangered014Candidate species for listing in designated critical habitats110141Source Author
Basing on this background, it is therefore the objective of this paper to outline the various issues that surround endangered species, the most endangered, causes of endangerment and recovery mechanisms.

2.0 The most endangered species
According to the IUCN Red List of Threatened Species, an evaluation of the conservation status of animal and plant species in all regions of the world indicates a risk of extinction for most species. The list has categorised the main threatened species into three

2.1 Critically Endagered Species
 These are faced with an extreme risk of extinction in the immediate future as a result of their population declining by 80 or more in the last 10 years. They also comprise of  less than 250 mature individuals or confined within a very small habitat area, a good example being the Javan rhino (IUCN, 2009).

2.2 Endangered species
 These face a very high risk of extinction in the near future since their population has declined by 50 or more in the past 10 years. In addition, they are confined within a fragmented habitat of less than 50,000 square kilometres with fewer than 2,500 mature individuals (IUCN, 2009). Tiger, cheetah, and African wild dog are some of the examples.

2.3 Vulnerable species
Vulnerable species face a high risk of extinction in the medium term with their population having reduced by 30 or more in the last 10 years and comprise of not more than 10,000 mature individuals occupying a fragmented habitat of less than 20,000 square kilometres. Such species include India bison, great whiteshark, polar bear, African lion, bumphead and raibow parrotfish, elephant, seahorses, Komodo dragon, rockhopper penguin and hippopotamus. In addition, several trees among them red cedar, sandalwood, shea butter, and Brazil nut trees, have been listed as vulnerable as well as many amphibians, bats, eagles, and parrots (IUCN, 2009).

3.0 Current Trend in Biodiversity
The IUCN Red List has further indicated that within the well-studied higher taxa, between 12 and 52 of species are facing risk of extinction (greenfacts.org, 2005). The figure shows species extinction rates in the course of time.

Source greenfacts.org
The evaluation done was based on the conservation status, with birds having the lowest percentage of extinction threat at 12. For conifers and mammals, the threat pattern is to a large extent similar, at 23 and 25 respectively while amphibians face a higher risk of 32 . A greater threat is evident among cyads at 52 globally (greenfacts.org, 2005). The rate of change in the overall threat status for various sets of species is as a result of several factors such as range, trend size and population. The figure illustrates the rate of change in the overall threat status for various sets of species based on diverse parameters.

Source greenfacts.org
4.0 Process of endangerment
The general process of endangerment can be divided into three major phases though the processes that lead to extinction are basically difficult to observe. At sometime in the course of history, the population approaches its carrying capacity but  the declining phase sets in especially in the case of progressive decline (Shogren  Tschirhart, 2001). The populations throughout the species range drastically diminish and eventually, individual populations may either become extinct or recover as illustrated.

Source Author
5.0 Causes of endangerment
5.1 Habitat destruction and Poaching
Habitat destruction  through agricultural activities has led to defforestation beside soil erosion and pollution from fertilizers as well as agrochemicals. The most affected habitat are the prairie, wetlands and forests. Additionally, building of dams ,dumping of industrial wastes and chemicals in rivers has posed a great threat to aquatic habitats. At the same time, poaching and illegal trade have resulted in some animals such as elephants and rhinoceroses being killed for the value of their tusks and hides while others such as the exotic tropical birds and parrots are used in pet trade.

5.2 Introduced species, Large preditors and Habitat fragmentation
Introduced species involve the introduction of certain plants or animals in habitats that they never existed resulting in competition for vital requirements with the native species or even causing diseases. The ecological balance is disrupted through displacement of competitively disadvantaged species. Another cause involves large preditors and trophies in which some preditors have been killed since they threaten humans or because they pose danger to domestic animals. Several types of poisonous snakes, lizards, bats, amphibians and condors are equally endangered due to their threatening physical traits or reputation. Habitat fragmentation is equally a source of endangerment which has been caused by patterns of land use by humans. It causes fragmentation of natural habitats and isolation of small populations and therefore dispersal form one habitat area to another becomes impossible.

6.0 Recovery mechanisms
These include Forest conservation whereby afforestation and preservation of existing forests is done. This gives a great chance of reducing species extinction and restoring richness of species to degraded lands. Another mechanism is legislation of laws protecting species such as the Endangered Species Act(ESA) which was created in 1973(csa, 2004). Its operation is based on the mandate of updating a list of endangered species and those whose population is declining as well as those at the verge of near extinction. This is followed by the implementation of a recovery strategy targeting the affected species with the aim of restoring its healthy population. Another act is the Marine Mammal Protection Act (MMPA) enacted in 1972 which serves to protect all mammalian species. In addition, the National Environment Policy Act (NEPA) covers environmental decision making so as to maintain good quality of the environment (seaworld, 2010). Measures for species recovery basically address issues of human encroachment and exploitation through trade, fishing, and hunting.

7.0 Conclusion
The number of species at risk is indeed very large and unless comprehensive conservational measures are taken, this trend is likely to increase with the current destructive human activities. Conservation efforts should focus on raising awareness, funding for conservation programs, taking action by governments to prevent unsustainable logging, fishing or hunting. It bears noting that, numerous benefits are associated with sustainable conservation efforts in terms of livelihood oppurtunities and economic benefits.