Extinctions are not unusual in nature. As the climate and landscape changes over millions of years, so too do the animals. They either evolve or become extinct. There are millions of species alive on Earth today, but because of habitat destruction and pollution, many species are threatened or endangered.
Throughout history there have been mass extinctions in which animals have been wiped out forever. A classic example is of course the dinosaurs 65 million years ago. The difference between then and now is that it is not giant meteors or other natural disasters that are threatening species, but human settlements encroaching upon mammal habitats.
Four Major Threats to Biodiversity
The four major threats to biodiversity are:
- Habitat Destruction
- Introduced Species
- Over Exploitation
- Food Chain Disruptions
Habitat Destruction – Humans effect mammalian habitats due to agriculture, forestry, mining, urban development and pollution. Habitat loss has occurred in terrestrial ecosystems as well as marine ecosystems and is believed to be responsible for around 73% of extinct, endangered, vulnerable or rare species of animal.
Introduced Species – Introduced species (eg; fox, zebra mussel) are believed to be responsible for around 40% of extinctions since 1750.
Over Exploitation – When humans harvest wild plants or animals there is risk of over exploitation. This basically means humans over-fishing and/or over-hunting which can lead to extinction because the animals cannot reproduce fast enough to keep up with human demand. It is possible to over-farm trees but over exploitation usually refers to animal life.
Food Chain Disruptions – The extinction of one species can potentially cause another to become extinct. This can occur if an animal feeds almost exclusively on one other species, however, this is not a common cause of extinctions. Usually a predator will move on to different prey.
Endangered Mammals
Many mammalian species have adapted to humans and their way of life, including horses, dogs, cats and mice, however many mammals are threatened or endangered due to human interference. According to the Earth’s Endangered Creatures website, there are currently 1568 endangered mammals.
And of the WWF’s (World Wildlife Fund/World Wide Fund for Nature) 2010 list of most threatened species, six of them are mammals. They are:
- Tiger
- Polar Bear
- Pacific Walrus
- Mountain Gorilla
- Javan Rhinoceros
- Giant Panda
For the full list, read The WWF’s Top Ten List of Threatened Species for 2010.
As forests over Europe and China were cleared during the last thousand years, mammals that live there have had less and less habitat, and inevitably will end up moving closer and closer to human settlements. Some animals such as bears and wolves, which may pose a threat to people, may be persecuted and potentially wiped out.
Resource and further reading:
You may also be interested in What’s the Difference Between Threatened and Endangered Species?, which explains the differences between vulnerable, threatened, endangered and critically endangered.
Campbell and Reece, 2002, 'Conservation Biology', in Biology 6th edition, ed. Benjamin Cummings, San Francisco, chap 55.
Roberta Goli - Roberta has a Bachelor of Science Degree (Zoology), has worked with animals for over 10 years and enjoys writing short stories and flash ...
