Habitats—The Basics
Habitats are the natural environments of plants and animals. Earth has many different habitats, from vast oceans to tropical rain forests, equatorial deserts to Arctic tundra. Between these extremes are others, such as grasslands, forests, rivers, lakes, and wetlands.
What makes a habitat unique? A combination of many things—including temperature, soil, rainfall, and geographic location—creates a habitat.
Highlights
Habitat Requirements
Migration
Biodiversity and Endangered Species
Invasive Species
Managing Habitats
Threats to Habitats
Related Links
| Habitat Requirements | TOP ^ |
All animals have basic survival needs, and a suitable habitat will provide them. The four basic habitat requirements are
• Food
• Shelter from weather and predators
• Water
• A place to raise young
In addition, each species has its own special needs. Wood ducks, for example, nest in tree cavities, while wild turkeys find meadows and grasslands to be good cover for their chicks.
Some animals, called generalist species, find what they need in a variety of habitats. They can cope with a large range of climate and vegetation types and easily adapt to different foods and environmental conditions. Examples of such species are squirrels, coyotes, raccoons, and crows.
Specialist species are less common than generalist species and can thrive only in a narrow range of habitats. These animals have limited climate and vegetation ranges and don't adapt well to new foods or environmental conditions. These species include grizzly bears, bobcats, and many types of birds.
Many species migrate, or move from one habitat area to another. They do so to feed, breed, or escape climate changes like freezing winters. Some, like northern elephant seals, need different types of habitats: deep, cold ocean waters for feeding, and warm beaches for breeding. Others live only in one type of habitat, like the band-tailed pigeon, which inhabits woodlands. Most birds migrate, but so do some species of bats, butterflies, whales, eels, and earthworms—and lots of others! Migrating animals may travel just a short distance or thousands of miles to make their annual journeys, and need habitats located in different places as well as passageways in between. Wildlife refuges often serve as stepping-stones, providing a safe stopover during their journeys.
| Biodiversity and Endangered Species | TOP ^ |
Our planet is teeming with life. Tigers and turtles, bats and bees, gnats and gnus, crabs and crabgrass—the list seems endless. We've named more than 1.5 million species, and suspect that millions more remain undiscovered. Scientists call this mind-boggling variety of life biodiversity. With so many species, it's surprising to realize that so many are in danger of becoming extinct.
Extinct species are plants and animals that once lived on Earth, but no longer live anywhere in the world. Endangered species are most in danger of extinction. Even large populations of animals can be at risk. Passenger pigeons once flew in flocks so large that they darkened America's skies. Over time, habitat destruction and hunting lessened the birds' numbers. The last one died alone in the Cincinnati Zoo in 1914.
Dinosaurs, dodo birds, and passenger pigeons are all extinct. Extinctions have always happened naturally, but in modern times, people have pushed wildlife to the brink much more quickly than ever before. We're losing wildlife at a rapid rate!
Endangered species are animals and plants that are in danger of becoming extinct. The U.S. Endangered Species Act of 1973 was passed to protect threatened wildlife and habitats so they don't go the way of the dodo.
Why do animals become endangered or extinct? The main reason is loss of habitat. Habitat destruction or fragmentation (the breaking up of natural habitat areas into progressively smaller patches) can make it tough for wildlife to survive. However, as people learn to take better care of plants, animals, and their habitats, endangered and threatened species may begin to make a comeback. In fact, bald eagles, black-footed ferrets, and many other species already have.
Accidentally or intentionally, people often relocate species to habitats where they aren't native. For example, the invasive zebra mussel was probably transported to North America in the ballast water of transatlantic ships. These relocated species are known as exotic or non-native species, and those likely to cause economic or environmental harm are called invasive species. These biological invaders can cause problems for native wildlife by preying on it, competing for essential resources, or destroying habitat. Once invasive species move in, they are very difficult to control or eliminate.
In parks, refuges, and reserves, wildlife managers work to maintain natural habitats—but they have to be careful. Their decisions affect all parts of the habitat ecosystem, from the smallest insect to the largest mammal. Every ecosystem sustains a delicately balanced and intricate web of life; its plants and animals are interdependent in complex ways. Each species plays a role in the ecosystem, so what affects one species, eventually affects them all.
Habitats can be changed in major ways by natural forces such as earthquakes, volcanoes, and hurricanes. People, too, now have the capacity to alter habitats in profound ways. As the worldwide population increases, and as people use more and more technology—for things such as transportation, heating, cooling, industry, agriculture, and forestry—entire ecosystems can be threatened.
We are at risk of losing the biodiversity of life on Earth, a sort of genetic "bank account" of known and unknown species that add value to ecology, medicines, the economy, and more.
What are the biggest threats to biodiversity? Just remember "HIPPO":
• Habitat loss
• Introduced species (exotic and invasive)
• Pollution
• Population growth
• Overconsumption
For more information on HIPPO, see page 8 of the Wild World Educator's Guide (PDF) >>
(To view or print the guide requires free Adobe Acrobat Reader.)
The factors that contribute to loss of biodiversity rarely occur alone. Usually it is the combined pressure of two or more of these factors that can cause a species to become threatened, endangered, or extinct.
The good news is that people can affect habitats in positive ways. How? Turn off a light when you leave a room, use less water to brush your teeth, ride your bike instead of using a car, and recycle. Even a small action can make a big difference for habitats.
Biodiversity
Explore biodiversity and how you can help protect the planet's diverse species at this American Museum of Natural History site.
Endangered Species
Get information about the animals and plants that are in danger of becoming extinct at this U.S. Fish and Wildlife Service site.
Invasive Species
Learn about the impacts of invasive species and discover the species that may be invading your habitats.
U.S. Endangered Species Act of 1973 (ESA)
Access the entire act at this U.S. Fish and Wildlife Service site.
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