Current Leading Causes of Species Extinction

Holocene Extinction Event

???

Holocene Extinction Event

6th mass extinctionSome natural causes such as

deglaciation, natural climatic shifts, natural rate of extinction

Main cause is….

Holocene Extinction Event

6th mass extinctionSome natural causes such as

deglaciation, natural climatic shifts, natural rate of extinction

Main cause is humans.

HOW?

Invasive (introduced) Species

Invasive (introduced) Species

Due to their lack of natural predators and the fact that native species are not adapted to their competition, invasive species are often very successful

Invasive (introduced) Species

Housecats???

84 million in U.S. New data suggests

they kill 2.9 billion birds and 12.5 billion mammals per year

http://theoatmeal.com/comics/cats_actually_kill

Habitat Destruction

85% of old growth forest in U.S. is gone. (some 2nd growth, some other uses)

Habitat Fragmentation

Breaking large ecosystems into smaller ones can lead to extinction.

Smaller islands of habitats can lead to: Loss of genetic

diversity (inbreeding) Inadequate food

supplies for large animals

Overexploitation

Pollution?

Not a major driver of extinction on land

Main pollution problem in water is eutrophication – too many nutrients running into ocean (mainly from agricultural run-off)

Overloaded nutrients cause algae blooms, which cause dead zones in the water due to oxygen deprivation

Guns + Animals = Good???

In U.S., money from every hunting license goes to buy wetlands -> Habitat Preservation

Over $500 million annually, leading to hundreds of thousands of acres of habitat protected in past few decades

In Africa, most funds for wildlife protection comes from hunting fees

So, how are we doing?

Since 1972, we’ve de-listed (saved) 28 species (25 additional species have been down-listed from endangered to threatened

Currently have 1,162 species on the Endangered Species List in U.S.