Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby reducing biodiversity and species abundance. Habitat destruction is the leading cause of biodiversity loss. Fragmentation and loss of habitat have become one of the most important topics of research in ecology as they are major threats to the survival of endangered species.

Habitat loss refers to the reduction in the amount of space where a particular species, or group of species can survive and reproduce.  Habitat loss is a consequence of human activities such as agriculture, urbanization, deforestation, resource extraction, alteration of the sea-floor due to trawling (fishing), or the release of pollutants. Habitat loss can also occur due to environmental changes, such as volcanic eruptions or tsunamis, or changes in climate or sea level, which today are largely the result of human activities.  Habitat loss can decrease biodiversity and alters species ranges and interactions.

Habitat loss is probably the greatest threat to the variety of life on this planet today. It is identified as a main threat to 85% of all species described in the IUCN’s Red List (those species officially classified as “Threatened” and “Endangered”).

Major Kinds of Habitat Loss

Habitat destruction: A bulldozer pushing down trees is the iconic image of habitat destruction. Other ways people directly destroy habitat include filling in wetlands, dredging rivers, mowing fields, and cutting down trees.

Habitat fragmentation: Much of the remaining terrestrial wildlife habitat in the U.S. has been cut up into fragments by roads and development. Aquatic species’ habitats have been fragmented by dams and water diversions. These fragments of habitat may not be large or connected enough to support species that need a large territory where they can find mates and food. The loss and fragmentation of habitats makes it difficult for migratory species to find places to rest and feed along their migration routes.

Habitat degradation: Pollution, invasive species, and disruption of ecosystem processes (such as changing the intensity of fires in an ecosystem) are some of the ways habitats can become so degraded, they no longer support native wildlife.

Main Causes of Habitat Loss

Agriculture: Much of the habitat loss from agriculture was done long ago when settlers converted forests and prairies to cropland. Today, there is increasing pressure to redevelop conservation lands for high-priced food and biofuel crops.

Land conversion for development: The conversion of lands that once provided wildlife habitat to housing developments, roads, office parks, strip malls, parking lots and industrial sites continues, even during the current economic crisis.

Water development: Dams and other water diversions siphon off and disconnect waters, changing hydrology and water chemistry (when nutrients are not able to flow downstream). During the dry season, the Colorado River has little to no water in it by the time it reaches the Sea of Cortez.

Pollution: Freshwater wildlife are most impacted by pollution. Pollutants such as untreated sewage, mining waste, acid rain, fertilizers and pesticides concentrate in rivers, lakes and wetlands and eventually end up in estuaries and the food web.

Climate change: The emerging driver of habitat loss is climate change. Wildlife that need the cool temperatures of high elevations, such as the American pika, may soon run out of habitat. Coastal wildlife may find their habitat underwater as sea levels rise.

Governmental leaders need to take action by addressing the underlying driving forces, rather than merely regulating the proximate causes. In a broader sense, governmental bodies at a local, national, and international scale need to emphasize:

1. Considering the irreplaceable ecosystem services provided by natural habitats.
2. Protecting remaining intact sections of natural habitat.
3. Finding ecological ways to increase agricultural output without increasing the total land in production.
4. Reducing human population and expansion. Apart from improving access to contraception globally, furthering gender equality also has a great benefit. When women have the same education (decision-making power), this generally leads to smaller families.