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Extinction
Mr. Poulin’s Science
Extinction
• The end of an organism or group of organisms
Extinction in the Modern World
• In the 1850’s people reported instances where flocks of passenger pigeons
would darken the sky, there were so many pigeons people could not even
begin to count how many there actually were… by 1914 there were little to
no passenger pigeons left…. Why?
• Massive commercial hunting
• Clearing forestry for pulp
Humans and the Rate of
Extinction
• It is easy to see that humans played a large role in the
eventual extinction of the passenger pigeon.
• As humans we are pushing for more resources to make
our lives easier
• Through human activities such as deforestation and the
burning of fossil fuels we are contributing to the
extinction of many species everyday.
Other Causes of Extinction
• It is estimated that nearly 500 million species have inhabited Earth at some
point or another. Of these species, more than 90% have either become
extinct or evolved into a new species.
• Mass extinctions were likely caused by catastrophes
• Climate change
• Competition - …
• If one species dies off then it will affect the entire ecosystem
Effects of Extinction
• The number of species in an ecosystem is described as the biological
diversity or biodiversity of the ecosystem.
• Ecosystems are fragile and if one part of the ecosystem is removed such as
one species, then the rest of the ecosystem may partially end up out of sync.
• For example, Sea Otters were overhunted along the coast of Asia, and after a while the
sea urchin grew in large numbers very quickly because they were not being hunted by
the Sea Otter. Because sea urchins eat kelp, and there was an increase in the sea urchin
population there was a quick decline in the amount of kelp as well as the fish that relied
on the kelp for survival.
Restoring Balance and Order
• History
• Late 1800s–early 1900s: predators, including wolves, are routinely killed in
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Yellowstone.
1926: The last wolf pack in Yellowstone is killed, although reports of single wolves
continue.
1974: The gray wolf is listed as endangered; recovery is mandated under the
Endangered Species Act.
1975: The long process to restore wolves in Yellowstone begins.
1991: Congress appropriates money for an EIS for wolf recovery.
Restoring Balance Cont.
• 1994: EIS completed for wolf reintroduction in Yellowstone and central Idaho. More than 160,000 public
comments received—the largest number of public comments on any federal proposal at that time.
• 1995 and 1996: 31 gray wolves from western Canada relocated to Yellowstone.
• 1997: 10 wolves from northwestern Montana relocated to Yellowstone National Park; US District Court
judge orders the removal of the reintroduced wolves in Yellowstone, but stays his order, pending appeal.
(Decision reversed in 2000.)
• 1995–2003: Wolves prey on livestock outside Yellowstone much less than expected: 256 sheep, 41 cattle
• 2005: Wolf management transfers from the federal government to the states of Idaho and Montana.
• 2008: Wolf populations in Montana, Idaho, and Wyoming removed from the endangered species list, then
returned to the list.
Restoring Balance Cont.
• 2009: The US Fish and Wildlife Service again delisted wolf populations in Montana
and Idaho, but not in Wyoming. A legal challenge resulted in the Northern Rocky
Mountain wolf population being returned to the federal endangered species list.
• 2011: Wolf populations were again delisted in Montana and Idaho by action of
Congress within the previous year, and the US Fish and Wildlife Service proposed
delisting wolves in Wyoming.
• 2012: Based on a Congressional directive, wolves were delisted in Wyoming and the
Northern Rocky Mountain Distinct Population is no longer listed.
Restoring the Balance
• Sea Otters have since been reintroduced to the Asian
coast lines and now the ecosystem is beginning to
look as it did, and the natural balance is being
restored.
• This is not always easy, but there are some success
stories.