How Are Humans Killing Wildlife? : A Level Environmental Studies

Humans have always had an impact on their surroundings, but we sometimes forget just how much damage we have had on wildlife. This article describes various ways this has occurred and how much of it is our fault.

How Humans Threaten Wildlife

Humans pose many threats to wildlife and ecosystems through deliberate exploitation, accidental harm from human activities, introduction of species into habitats, habitat change and destruction. These activities result in species becoming vulnerable (under threat) or endangered (low in numbers and in danger of extinction).


Deliberate Exploitation
Humans deliberately exploit wildlife as a resource for several purposes, over exploitation results in declining numbers of these species:


Food
This is the main reason species are exploited and can result in over harvesting of wild populations. Fish such as cod, swordfish and tuna are over fished.
Bush meat involves the killing of a range of species including apes, monkeys, rodents and birds for food including endangered species.
Additionally, wild plants can be over harvested e.g. wild ginseng has been over harvested.


Fashion
Animals are also exploited for their furs, skins and shells; large cats such as leopards are hunted for their skins which are used for coats, turtle shells are used for jewellery and crocodile leather is used for shoes and handbags.


Furniture and Ornaments
Tropical hardwoods such as teak and mahogany harvested from tropical rainforests are used for furniture.
Animal products are also used; for example ivory, turtle shell and coral are used to make ornaments.


Traditional Medicines
A large number of traditional medicines, such as Chinese medicine use plants and animal products for the treatment of ailments, e.g. rhino horn, tiger bone, bear bile and snakes. Demand for these treatments results in species becoming endangered.


Entertainment
Species are removed from the wild for entertainment or as pets. Some animals are killed during capture, and often young are taken away from their parents; this can also result in habitat destruction. Organisms taken from the wild include tropical plants, parrots, reptiles, apes and tropical fish.


Other Products
Wildlife may be exploited for other products such as whale oils for use in cosmetics, or animals such as chimpanzees for testing.


Accidental Harm from Human Activities
Commercial fishing is often not a selective process; other species and immature specimens of the target species are also caught. This excess catch is known as by-catch, which are generally not of commercial value and is thrown overboard. For example nets used in tuna fishing catch other species such as dolphins.

Harvesting of crops destroys habitats and can also kill species in the process, for example during silage and hay cutting small animals can be killed, e.g. harvest mice in wheat crops or nesting birds. The use of agrichemicals such as pesticides also results in the death of organisms.

Additionally, roads affect wildlife, their construction destroys and fragments habitats, displacing and killing species, while the traffic on them results in the death of animals (road kill) e.g. badgers, hedgehogs, toads and deer.


Introduced Species
Species can be introduced into habitats where they are not native accidentally or intentionally, affecting native species and damaging habitats. Organisms can be accidentally introduced into a new habitat through transportation on vehicles or on goods, for example aquatic species can be introduced in water released from ship ballast tanks. Intentional introduction can be through the planting of garden plants, introduction of biological control organisms or as a food or other resource.
Once an introduced species becomes established in a habitat it can be hard to eliminate.

The introduced species can cause damage, as in their new environment they are often free from natural predators, competitors, pathogens and parasites that usually limit their numbers.

Without these population-limiting factors introduced species numbers can rapidly increase. Advantageous adaptations to the environment or being more aggressive in the way they behave or grow can overwhelm native species. Introduced species can predate or compete with native species, or diseases can be introduced.

Predation of native species can dramatically affect their numbers; species may be introduced as a biological control for native pest species, as a resource or just accidentally released.

Introduced species may compete with native species for the same resource such as food and/or space, but due to adaptations they possess, such as faster growth rate, higher reproduction rate or the ability to utilise a wider range of food sources, they can out compete the native species, which decrease in number.

Deliberate Eradication of Species
Some species populations are intentionally reduced in number (culling) or eradicated by humans, as they compete with our uses of resources in the area. Livestock predators and species deemed to be dangerous to humans have been eradicated through culling, trapping and poisoning.

Also species seen as competitors for resources that we use are also eradicated, through hunting and pesticides. Some of species that have been subjected to eradication include bears, wolves, foxes, otters, birds of prey and agricultural pests.


This article has been put together by the distance learning organisation Start Learning who are experts in home study.
If you want to find out more about A Level Environmental Studies or many other distance learning courses please browse their website: Start Learning

Kerrana McAvoy
Academic Director
Start Learning