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.
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.
Introduction of Exotic Species
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.
Illegal Hunting and Fishing
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.
Unfortunately, poachers are often hard to catch because they are deliberately trying to evade authorities, and they operate in areas where enforcement is weak.
Of course, species endangerment and extinction can happen without human interference. Extinction is a natural part of evolution. Fossil records show that long before people came along, factors such as overpopulation, competition, sudden climatic change, and catastrophic events like volcanic eruptions and earthquakes drove the decline of numerous species.
Determining Which Species Are at Risk
There are a few warning signs that a species could become extinct. If a species has some economic importance, such as the Atlantic salmon, it may be at risk. Surprisingly, large predators, who we might expect to have an advantage over other species, are often at risk as well. This list includes grizzly bears, bald eagles, and gray wolves.