Human Impacts on Animals

Value of Animals

Did you ever try to calculate in dollars the pleasure you receive from seeing wildlife in nature - a flock of birds returning from their winter feeding grounds or possibly a whale out a sea?  Every year birds, mammals, and insects bring joy to thousands of wildlife enthusiasts who enjoy wildlife because of its mere existence - the sound of a bird's song or the sight of a monarch fluttering past.  

The value of animals extends far beyond existence values, they provide an immense number of ecological services. A single chickadee consumes thousands of insect larvae in a single day, while that is a means of survival for the chickadee it also purges plants of pests.  Gulls, crows and pigeons have adapted to human lifestyles by picking up garbage and discarded bits of food. In a very real way animals are beneficial - not only in terms of ecosystem functions, but also in the economic terms humans measure their lives in.
(read more ...) 

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

Types of Animals

• Birds
• Mammals
• Reptiles
• Amphibians
• Fish
• Invertebrates
  • Insects
  • Other invertebrates (e.g. snails)

 (read more ...) 

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.
(read more ...)

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.
(read more ...)

Wildlife often depend on particular types of habitat.  This image shows the impacts of urban sprawl on the California Gnatcatcher's habitat.

The Conservation of Animals

Different species typically require different methods of conservation.  There are three primary ways people have tried to conserve, restore and protect animals: 

• Habitat conservation

• Species focused conservation

• Ecosystem conservation

While there is much discussion about which single conservation method is best for wildlife, there is considerable value in using a diversity of approaches and techniques for protecting wildlife.
(read more ...)

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