Species overview

One in four mammals are believed to be at risk of extinction,
and is figure is likely to increase unless drastic action is taken. The three main threats to mammalian biodiversity are habitat loss, introduced species and overexploitation. Find out more about the impact of these threats by following the links below:

Follow the links for general information on the main threat processes affecting mammals:

Habitat destruction
Pollution
Climate change
Introduced and invasive species
Overexploitation
Disease

 

Habitat destruction
Human alteration of habitat is the single biggest threat to mammals.  Practices such as logging and agriculture can destroy natural habitat, while roads, urban areas and the damning of rivers can act as barriers to movement, preventing mammals from finding food or mates, or avoiding natural disasters.

Habitat loss is the greatest cause of the population decline,
and continues to be the main threat to the giant panda. Large areas of forest are cleared for agriculture, timber and firewood, and the pandas have been forced up higher into the mountains as China’s growing human population encroaches onto their habitat. The pandas are being forced into smaller and increasingly isolated pockets of habitat where there is often insufficient bamboo to support the declining populations.

Introduced and invasive species
Humans have spread a great many non-native animals
and plants around the world and they have done so at an unprecedented rate in the last century.  The establishment and spread of non-native or “exotic” species are a major threat to worldwide biodiversity, and many species have been greatly impacted by introduced species through direct predation, competition and the introduction of diseases.

The spread of black and brown rats around the globe has led
to the extinction of many island species over the past 500 years and continues to threaten mammals such as the terrestrial
(or ground-dwelling) New Zealand lesser short-tailed bat.

Overexploitation
Species that are hunted for their meat, or whose body parts
are used in traditional medicines and potions are vulnerable
to overexploitation.

The short-tailed chinchilla is famous for its beautiful bluish-grey fur, which is extremely soft and dense and considered to be
one of the most valuable in the world. The species has been harvested for its fur and for their meat since ancient times. However, the short-tailed chinchilla was driven to the brink of extinction by commercial exploitation, which began in the early nineteenth century. The dense silky fur is considered to be one of the most valuable in the world, and as populations declined market prices soared, stimulating increased efforts to capture the chinchillas.

Pollution
A number of different pollutants negatively impact mammal species, particularly those inhabiting aquatic environments, such as marine mammals and the river dolphins of Asia and South America. Rivers and streams are frequently polluted by
a wide range of agricultural, industrial and other wastes, many of which have not been properly treated. These pollutants can lead to a decrease in oxygen levels in the water, a feature often associated with dense algal blooms. Many species die as a result of suffocation or starvation as their food supplies are rapidly destroyed by the algae. Non-lethal effects of pollutants include, reducing reproductive success, weakening immunity and indirectly reducing food and/or habitat availability.

Climate change
Global climate change is a huge issue facing life on Earth.
The consensus opinion is that human activities have caused stable climatic systems to change unpredictably. Temperatures and rainfall patterns are changing, resulting in global warming and an increased frequency of climatic disasters or “extreme weather”, such as hurricanes and tornados, droughts and floods. All life on earth is likely to be affected, but some
groups appear to be more vulnerable that others.

The mountain pygmy possum from southeast Australia is
reliant on winter snow-fall for its annual hibernation. This
tiny marsupial has been forced higher up into the mountains
by rising temperatures caused by global warming. Continued
long-term declines in populations are predicted as temperatures rise and snow cover decreases due to
global warming.

Disease
Disease can be a major threat to all species, particularly if populations have already experienced declines as a result of other factors.  Virulent diseases caused by viruses, fungi and bacteria are a particular threat to amphibians, killing thousands, if not millions, of animals each year.  Find out more about how disease is emerging as one of the major threats to amphibian species worldwide here (link to Amphibians threats page)

Human – Animal Conflict
Mammals such as elephants are frequently driven out of their natural habitats and forced into close contact with humans. When they enter agricultural areas they can cause damage
to crops which may result in conflict with local people.

Asian elephants are increasingly coming into contact with farmers and local people as their feeding grounds are destroyed. They raid crops, destroy properties, and sometimes even kill people. The villagers often retaliate by killing the elephants, and experts now believe this to be the main
cause of elephant deaths in Asia.


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