Habitat Conservation

Habitat Protection

The mantra of many conservation efforts is that species cannot survive without habitat. Therefore, efforts to conserve species have often necessarily begun by identifying the habitats those species rely on and conserving those lands. These efforts stirred a lengthy academic debate over the value of conserving one large site which might be self-sustaining and avoid challenges smaller sites face - such as management of invasive species, versus the value of conserving many smaller sites where you might conserve more of the habitat known to be used by species and by conserving multiple sites there might be a degree of redundancy in the effort rather than relying on the performance of a single site. This debate is known as the SLOSS (Single Large or Several Small) question and ultimately both approaches have their advantages.

Thousands of people travel to see whales -  both in captivity (e.g. Seaworld) and in the wild.

Role of Disturbance

More recently habitat conservation efforts have recognized that simply setting land aside and managing the site as a wild area is not sufficient to achieve lofty conservation goals. The habitats that species rely on can often be maintained through intensive management interventions, but plant and wildlife communities have evolved to take advantage of large-scale processes that create disturbance. Disturbances like fire, windstorms and even disease outbreaks create gaps in communities that provide opportunities for new communities to develop and often for the diversity of the community to increase.

Animal Extinctions and Declines

Animal populations fluctuate naturally, some more than others.  Populations might increase in response to a particularly good food year, while declines would accompany a poor food year or when predators are abundant.  When a species' population reaches zero individuals it is extinct. Many species become doomed for eventual extinction far before the last individual is lost as the "effective population size" may reach zero before the actual population if males and females can't locate each other or if the final population is skewed such that mating is impossible.

While extinctions are a natural feature of biological systems, extinctions are relatively rare. Focused "extinction events" such as the one that eliminated the dinosaurs millions of years ago have occurred only a handful of times in geologic history and have typically been followed by rapid evolution of new species. Humans have had a large impact on the populations of many different types of animals. While we have recorded steep population declines for many species, with island species suffering the worst fates. Many believe that the rates of extinction we are experiencing today are unprecedented in geologic history and may ultimately impact human populations.
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Passenger pigeons were once abundant throughout North America.  Their colonial roosting made them easy targets for hunters which eventually caused their extinction.

Human Impacts on Animals

As human population continues to expand the conflicts between human habitat and animal habitat grow.  Cities expanding into the countryside impact habitat that formerly served as home to various species.  Large wide-ranging animals like wolves, bears and elephants are often the first to be impacted by declines in habitat quality and quantity. Their size means they need lots of food, to find that food animals often have to roam great distances and feed on different types of food at different times of the year. As individuals are forced to use smaller and smaller areas they begin to influence the populations of their prey.
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Wildlife often depend on particular types of habitat.  This image shows the impacts of urban sprawl on the California Gnatcatcher's habitat.

 
Once hunted nearly to extinction, populations of gray wolves are beginning to rebound.