Reasons Why Animals Become Endangered

An animal may become endangered for several different reasons

Bornean Orangutan mother with baby
Orangutan habitat destruction due to logging, mining and forest fires, as well as fragmentation by roads, has been increasing rapidly in the last decade. Manoj Shah/ Stone/ Getty Images

We know that more and more animal species are on the verge of extinction, but why? There are several major reasons why a species may become endangered, and as you might expect, humans play a role in quite a few of them. The biggest threat to endangered animals is human encroachment on their habitats.

Habitat Destruction and Pollution

Every living organism needs a place to live, but a habitat is not just a residence.

It also is where an animal finds food, raises its young and allows the next generation to take over. 

Humans destroy animal habitats in a number of different ways: building houses, clearing forests to get lumber and farm 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. Some species die outright while others are pushed into areas where they can't find food and shelter. And when one animal suffers from human encroachment, it affects many other species in its food web, so more than one species' population begins to decline.

Habitat destruction is the number one reason for animal endangerment. But there are other causes. 

Exotic Species Can Wreck Habitats

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.

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.

Native species haven't developed natural defenses for an exotic species, and vice versa. These factors can endanger both species' survival.

One example of endangerment due to both competition and predation is the Galapagos tortoise. Non-native goats were introduced to the Galapagos Islands during the 20th century. These goats fed on the tortoises' food supply, causing the number of tortoises to decline rapidly. 

Illegal Hunting Can Endanger Species

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. 

Poachers are often hard to catch because they are deliberately trying to evade authorities, and they operate in areas where enforcement is traditionally weak. 

And poachers have developed sophisticated techniques for smuggling animals. Baby bears, leopards, and monkeys have been sedated and stuffed into suitcases for transport. Live animals are sold to people who want exotic pets or medical research subjects. Animal pelts and other body parts are also secretly smuggled across borders and sold through black market networks of buyers who pay high prices for illegal animal products.

Legal Exploitation Causes Animal Endangerment

Even legal hunting, fishing and gathering of wild species can lead to population reductions that cause species to become endangered. A lack of restriction on the whaling industry in the 20th century is one example; it wasn't until several whale species were nearing extinction that countries agreed to abide by an international moratorium. Some whale species have rebounded thanks to this moratorium but others remain at risk. 

Animal Endangerment Also Has Natural Causes 

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 overspecialization, competition, sudden climatic change and catastrophic events like volcanic eruptions and earthquakes drove the decline of numerous species.

How Are Animals Endangered?

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.

 A species whose gestational period is lengthy, or who have small numbers of offspring at each birth have the potential to become endangered more readily. The mountain gorilla and California condor are two examples.  And species with weak genetic makeup, like manatees or giant pandas, have more risk of extinction with each generation.