“Passenger pigeon shoot”
The Illustrated Shooting and Dramatic News, Public Domain, via Wiki Commons

In the 1800’s the sky was often blackened in Easter North America by huge flocks of the Passenger Pigeon.  A migratory species, flocks numbering in the billions were a sight without comparison.  Hunting and habitat loss due to deforestation for farming and cities resulted in the most abundant bird in the 19th century becoming extinct by the early 20th century.  Martha, thought to be the last passenger pigeon, held in captivity in the Cincinnati Zoo, died September 1, 1914.  Thousands of species are in danger of suffering the fate of the Passenger Pigeon.

We all have a responsibility to protect endangered species, both for their sake and for the sake of our own future generations.—Loretta Lynch

What are Endangered Species?

According to National Geographic, an endangered species is any organism that is at a serious risk of extinction.  There are so few left of an endangered organism that there is not enough of a breeding population to keep the species going.  Current estimates suggest that 1/3 of the world’s amphibians, 1/4 of the world’s mammals and 1/8 of the world’s birds are endangered.  There are about 1300 endangered or threatened species in North America alone.  Of nearly 60,000 species assessed so far, 20,000 of those species are at risk of extinction.

How Are Endangered Species Classified?

Species are classified as endangered based on 5 criteria:

  1. Population reduction rate – measured over at least a 10 year period with a reduction of at least 50%.
  2. Geographic range – it is found in an area less than 5,000 square kilometers.
  3. Population size – an endangered species population has declined by at least 20 percent within five years or two generations.
  4. Population restrictions – species are endangered when their population is restricted to less than 250 mature individuals.
  5. Probability of extinction – based on a complicated mathematical formula developed by scientists in several disciplines.

Threatened Baby Bog Turtle-Rosie Walunas/USFWS, CC BY 2.0, via flickr

Eastern Prairie White Fringed Orchid (Platanthera leucophaea) ~Wisconsin Endangered
John Mayer, CC BY-SA 2.0, via flickr

How Species Become Endangered

Species become endangered for many reasons.  In the past, natural climate changes and environmental catastrophes have resulted in organism extinction.  Today, these changes do contribute but by far human impact results in the greatest decline of populations.

The two main reasons species become endangered are habitat loss and loss of genetic diversity.  Other reasons include:

  • hunting/poaching
  • disease
  • pollution
  • invasive species
  • collection of individual organisms for private collections or as pets

The current rate of extinction is thought to be greater than the expected natural rate without human interference.  It is thought that a great many species go extinct before they’ve been discovered.


Why Should Endangered Species Concern Us?

Species are disappearing at an alarming rate.  World biodiversity is essential to support the health of our planet.  Ecosystems must be made up of a diverse number of species to be healthy.  Ecosystem health is essential for our own survival.  High biodiversity helps to regulate the climate.  It also contributes to the following:

  • clean air and water
  • adequate food sources
  • medicines
  • building and clothing material
  • fertile soils

We are part of the interconnected web of life on our planet. Understanding the reasons organisms become endangered is vital not only to their continued existence but also to our own survival.

Care for your planet by caring for its species.

Kimberly Tamkun/USFWS, CC BY 2.0, via flickr

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