Fortunately, conservation efforts around the world are bent on helping these endangered animals revitalize their dwindling populations through a variety of humanitarian efforts, including curtailing illegal poaching, halting pollution, and habitat destruction, and curtailing the introduction of exotic species into new habitats. Every living organism needs a place to live, but a habitat is not just a residence, it is also where an animal finds food, raises its young and allows the next generation to take over.
Unfortunately, humans destroy animal habitats in a number of different ways: building houses, clearing forests to get lumber and plant crops, draining rivers to bring water to those crops, and paving over meadows to make streets and parking lots.
Habitat destruction is the number one reason for animal endangerment, which is why conservation groups work diligently to reverse the effects of human developments. Many non-profit groups like the Nature Conservancy clean up coastlines and establish nature preserves to prevent further harm to native environments and species around the world.
In addition to physical encroachment, human development of animals' habitats pollutes the natural landscape with petroleum products, pesticides, and other chemicals, which destroy food sources and viable shelters for the creatures and plants of that area. As a result, some species die outright while others are pushed into areas where they can't find food and shelter.
Worse yet, when one animal population suffers it affects many other species in its food web so more than one species' population is likely to decline. An exotic species is an animal, plant, or insect that is introduced into a place where it did not evolve naturally. Exotic species often have a predatory or competitive advantage over native species, which have been a part of a particular biological environment for centuries, because even though native species are well adapted to their surroundings, they may not be able to deal with species that closely compete with them for food.
Basically, native species haven't developed natural defenses for an exotic species and vice versa. These goats fed on the tortoises' food supply, causing the number of tortoises to decline rapidly. Because the tortoises could not defend themselves or stop the overpopulation of goats on the island, they were forced to abandon their native feeding grounds.
Many countries have passed laws banning specific exotic species known to endanger native habitats from entering the country. Exotic species are sometimes referred to as invasive species, especially in cases of banning them. For instance, the United Kingdom has placed raccoons, mongooses, and cabbages on their invasive species list, all of which are barred from entering the country.
When hunters ignore rules that regulate the number of animals that should be hunted a practice known as poaching , they can reduce populations to the point that species become endangered. For this reason, a species can be of least concern in one area and endangered in another.
The gray whale, for instance, has a healthy population in the eastern Pacific Ocean, along the coast of North and South America. The population in the western Pacific, however, is critically endangered.
Least Concern Least concern is the lowest level of conservation. A species of least concern is one that has a widespread and abundant population. Human beings are a species of least concern, along with most domestic animal s, such as dogs and cats.
Many wild animals, such as pigeons and houseflies, are also classified as least concern. Near Threatened A near threatened species is one that is likely to qualify for a threatened category in the near future. Many species of violet s, native to tropical jungle s in South America and Africa, are near threatened, for instance. They have healthy populations, but their rain forest habitat is disappearing at a fast pace. People are cutting down huge areas of rain forest for development and timber.
Many violet species are likely to become threatened. Vulnerable Species The definitions of the three threatened categories vulnerable, endangered, and critically endangered are based on five criteria: population reduction rate, geographic range, population size, population restrictions, and probability of extinction. Threatened categories have different threshold s for these criteria. As the population and range of the species decreases, the species becomes more threatened.
This decline is measured over 10 years or three generations of the species, whichever is longer. A generation is the period of time between the birth of an animal and the time it is able to reproduce. Mice are able to reproduce when they are about one month old. Mouse populations are mostly tracked over year periods. An elephant's generation lasts about 15 years. So, elephant populations are measured over year periods. A species is vulnerable if its population has declined at least 50 percent and the cause of the decline is known.
Habitat loss is the leading known cause of population decline. A species is also classified as vulnerable if its population has declined at least 30 percent and the cause of the decline is not known.
A new, unknown virus, for example, could kill hundreds or even thousands of individuals before being identified.
An area of occupancy is where a specific population of that species resides. This area is often a breeding or nesting site in a species range.
The species is also vulnerable if that population declines by at least 10 percent within 10 years or three generations, whichever is longer.
A species is vulnerable if it is restricted to less than 1, mature individuals or an area of occupancy of less than 20 square kilometers 8 square miles. These formulas calculate the chances a species can survive, without human protection, in the wild.
Vulnerable Species: Ethiopian Banana Frog The Ethiopian banana frog Afrixalus enseticola is a small frog native to high- altitude areas of southern Ethiopia. It is a vulnerable species because its area of occupancy is less than 2, square kilometers square miles. The extent and quality of its forest habitat are in decline.
Threats to this habitat include forest clearance, mostly for housing and agriculture. Vulnerable Species: Snaggletooth Shark The snaggletooth shark Hemipristis elongatus is found in the tropical , coastal waters of the Indian and Pacific Oceans. Its area of occupancy is enormous, from southeast Africa to the Philippines, and from China to Australia.
However, the snaggletooth shark is a vulnerable species because of a severe population reduction rate. Its population has fallen more than 10 percent over 10 years. The number of sharks is declining due to fisheries, especially in the Java Sea and Gulf of Thailand.
They are sold in commercial fish markets, as well as restaurants. Galapagos kelp is classified as vulnerable because its population has declined more than 10 percent over 10 years. Climate change is the leading cause of decline among Galapagos kelp. El Nino , the natural weather pattern that brings unusually warm water to the Galapagos, is the leading agent of climate change in this area.
Galapagos kelp is a cold-water species and does not adapt quickly to changes in water temperature. Endangered Species 1 Population reduction rate A species is classified as endangered when its population has declined between 50 and 70 percent. A species is classified as endangered when its population has declined at least 70 percent and the cause of the decline is known.
A species is also classified as endangered when its population has declined at least 50 percent and the cause of the decline is not known. When a species population declines by at least 20 percent within five years or two generations, it is also classified as endangered.
Endangered Species: Siberian Sturgeon The Siberian sturgeon Acipenser baerii is a large fish found in rivers and lakes throughout the Siberian region of Russia. The Siberian sturgeon is a benthic species. Benthic species live at the bottom of a body of water. The Siberian sturgeon is an endangered species because its total population has declined between 50 and 80 percent during the past 60 years three generations of sturgeon.
Overfishing, poach ing, and dam construction have caused this decline. It is an endangered species because it has a very small population.
The bird is only found on a single island, meaning both its extent of occurrence and area of occupancy are very small. The Tahiti reed-warbler is also endangered because of human activity. The bird nests in bamboo and feeds on flowers and insects that live there. As development and invasive species such as Miconia destroy the bamboo forests, the population of Tahiti reed-warblers continues to shrink. Ebony is an endangered species because many biologists calculate its probability of extinction in the wild is at least 20 percent within five generations.
Ebony is threatened due to overharvest ing. Ebony trees produce a very heavy, dark wood. When polished, ebony can be mistaken for black marble or other stone. For centuries, ebony trees have been harvested for furniture and sculptural uses such as chess pieces.
Most ebony, however, is harvested to make musical instruments such as piano key s and the fingerboard s of stringed instruments.
A species is classified as critically endangered when its population has declined at least 90 percent and the cause of the decline is known. Losing even a single species can have disastrous impacts on the rest of the ecosystem, because the effects will be felt throughout the food chain.
From providing cures to deadly diseases to maintaining natural ecosystems and improving overall quality of life, the benefits of preserving threatened and endangered species are invaluable. When the U. In order to be listed as a candidate, a species has to qualify for protected status under the Endangered Species Act. Whether or not a species is listed as endangered or threatened then depends on a number of factors, including the urgency and whether adequate protections exist through other means.
When deciding whether a species should be added to the Endangered Species List, the following criteria are evaluated:. If the answer to one or more of the above questions is yes, then the species can be listed under the Endangered Species Act. Once a species becomes listed as "threatened" or "endangered," it receives special protections by the federal government. A listed plant is protected if on federal property or if federal actions are involved, such as the issuing of a federal permit on private land.
The term "take" is used in the Endangered Species Act to include "harass, harm, pursue, hunt, shoot, wound, kill trap, capture, or collect, or to attempt to engage in any such conduct. The primary goal of the Endangered Species Act is to make species' populations healthy and vital so they can be delisted from the Endangered Species Act.
Under the Endangered Species Act, the U. The two organizations actively invest time and resources to help bring endangered or threatened species back from the brink of extinction. The Declining Amphibian Phenomenon is one of the more obvious measures of the declining state of our biosphere due to pollution. Although biologists have been unable to isolate a single cause for the recent rapid decline in numbers and extinctions of many species, it appears that much of it is due to pollution. In the Sierra Nevada, cell damage due to excessive ultraviolet-B radiation, too strong with the thinning of the ozone layer.
Invasive species are a major cause of loss of diversity of both plants and animals. When a new species arrives with no natural predators to keep it in check, it can take over. A familiar example is the brown tree snake inadvertently arriving in Guam on a cargo ship following WWII.
The venomous brown snake has decimated on virtually all of the local bird, fruit bat and lizard populations [8]. And one other example happened in the Great Lakes region of the United States, where the Zebra Mussel was accidentally introduced. Many of the native mussel species in the Great Lakes have now become threatened or endangered due to the presence of the highly competitive Zebra Mussel.
Is pretty much the mentality in rural America. And yet in a surprising twist, Los Angeles, a city and its suburbs home to 19 million people is an enclave where mountain lions live side-by-side with humans [9]. Mountain lions have been roaming the city for at least 30 years and The National Park Service has been studying them since , curious how mountain lions survive in an increasingly fragmented and urbanized landscape [10]. A recent citing prompted this response from a year old resident. On the other hand, as our populations increase and more people move into areas where wildlife previously lived in abundance, new human-wildlife conflicts arise.
Sadly, in many cases, wildlife is killed when they cause too big harm to farmers by hunting livestock or destroying crops. For wildlife populations that have already been reduced due to loss of habitat and other issues, such conflicts can increase the chances that a species will become threatened or endangered. Diseases kill humans and animals alike.
The Ebola virus killed 5, critically endangered western gorillas between and at the Lossi Sanctuary and other hundreds of gorillas in the Odzala-Kokoua National Park in [12]. A deadly fungus from Europe, where it is harmless to bats has spread to North America killing 6 million bats and taking many species to the brink of extinction. It was a fungus that destroyed the American chestnut tree, one hundred-foot hardwoods that once numbered in the billions in eastern forests of the United States, and a significant food source for a variety of wildlife, but which were virtually eliminated by a fungal pathogen accidentally imported into the United States from Asia [14].
Because the American Chestnut tree had evolved in conditions without the presence of the fungus, it lacked the natural resistance to survive.
Currently, there is ongoing research with the aim of creating a hybrid chestnut variety that is a cross between the American Chestnut and a variety of Chinese chestnut that is resistant to the chestnut fungus. It is believed that reproduction rates are a natural way of maintaining a population equilibrium.
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