Transcript 0part_3_ch_1.2-_endangered_species_and_1.3_extinction

Species whose populations decline
below a certain level are considered to
be at risk.
 In Canada, there are 585 species in
various degrees of risk as of April 2009,
according to COSEWIC (Committee of
the Status of Endangered Wildlife in
Canada).

Summary table of Wildlife species assessed by COSEWIC
http://www.cosewic.gc.ca/eng/sct0/index_e.cfm#sar
The reasons for an ecosystem decline, are the
same reasons why certain species are put at
risk.
 1. Loss of habitat
 2. Pollution
 3. Diseases
 4. Climate change / global warming
 5. Accidental introduction of new species
 6. Over harvesting certain species
 7. Competition
 8. Increased use of pesticides and fertilizers
 9. Natural environmental change / Mass
Extinction


1. EXTINCT – A species that is not found
anywhere
EXAMPLES:
 Blue Walleye (Type of Fish-1965 )
 Passenger Pigeon ( 1914 )

Passenger Pigeon
Blue Walleye
A species that is close to extinction in all
parts of Canada or in a significantly
large location.
 EXAMPLES:
 Eastern Cougar ( very rare sightings)
 Beluga Whale ( St. Lawrence River )
 Gorillas
 Atlantic Salmon ( very shortly )

Beluga Whale
Eastern Cougar
Gorilla
Atlantic Salmon
Any species that no longer exists in one
part of Canada, but can be found in
others
 EXAMPLES:
 Grizzly Bear (no longer in Man. and Sask
but found in Alberta and BC.)

Any species that is likely to become
endangered if factors that make it
vulnerable are not reversed.
 EXAMPLES:
 Wood Bison ( small number)
 Anatum Peregrine Falcon ( captive
breeding is helping to restore
population.)

Peregrine Falcon
Wood Bison
Any species that is at risk because of low
or declining numbers at the fringe of its
range or in some restricted area.
 EXAMPLES:
 Grey Fox
 Atlantic Cod
 Blue Heron
 White tail Deer

Grey Fox
Heron
Atlantic Cod
Blue
WhiteTailed
Deer
Which at-risk category is the most
devastating?
 Answer:
 Extinction

In the modern world, extinction rates of species on
planet Earth are increasing at an alarming rate.
 Between 1600 – 1900 the estimate is that one
species went extinct every four years.
 It is estimated that we lose one species every 30
minutes, that is about 17,500 per year… Gone
Forever!
 Species extinction rates are increasing dramatically
as the human population grows.
 Species at risk of extinction is growing, at the rate
of about 80 species per year.

Some species learn to adapt to major
changes, others die.
 In either case, this has major effects on
each ecosystem and food chain.

The number and variety of species in an
ecosystem is described as the biological
diversity or BIODIVERSITY of the
ecosystem.
 The reduction in biodiversity caused by
the extinction of a single species can
cause a “domino effect” with many
negative effects.
 When the threatened species acts as a
predator, it keeps the population of its
prey in check.

When it acts as prey, it provides an
important food source.
 So, An increase in Biodiversity = Healthy
ecosystem.
 A decrease in Biodiversity = greater
chance of Ecosystem Collapse.


Decrease in the Sea Otter ( predator )
Means an increase in Sea Urchins
Means a decrease in Kelp ( form of
seaweed)
 Means a decrease in Fish ( relies on
seaweed for habitat and food )




By protecting the Sea Otters caused a
increase in Fish which balanced out the
food chain and therefore the ecosystem.
A) Threatened
 B) Endangered
 C) Extirpated
