Download Extinction and Extirpation

Grade 9 Science - Reducing Biodiversity
Extinction: the disappearance of every individual of a species from the entire
planet (once extinct they are GONE). Different research comes up with different
numbers but it is estimated that 50 – 100 species go extinct every day! Don’t forget,
while we tend to think more about animals, any living organism has the potential to go
extinct… and many plants are going extinct due to deforestation (cutting down trees)
and climate change. Plants can’t move when there is a problem, they just die.
→ Dodo Bird – humans introduced dogs, pigs and rats which essentially ate eggs,
and humans hunted them… wiping them out
→ Dinosaurs – meteor crash on earth changed climate (theory anyway)
→ Wooly Mammoth – went extinct due to climate change at end of major glacial age
→ West African black rhino – extinct due to loss of habitat and mainly due to
poaching (illegal hunting for the rhinos horn)
→ Golden Toad – extinct due to pollution and global warming
→ Passenger Pigeon – hunted to extinction
→ Blue Walleye – a fish from the Great Lakes … extinct due to overfishing
Exterpation: localized extinction – disappearance of a species from a particular
area, but they are still found elsewhere (therefore still possible to bring back).
→ Greater Prairie Chicken – use to be common across the Canadian prairies but
loss of habitat has caused them to be extirpated from Canada
→ Paddlefish – once common in Great Lakes, now found in the Mississippi River
system in USA
→ Gray Whale – once common in the Atlantic Ocean off the coast of Canada, was
extirpated by whaling
→ Grizzly Bear – once common in the prairies, even around Calgary, was hunted
and lost habitat and extirpated … are now found only in foothills and mountains
→ Blue Eyed Mary – flower use to be common in forests in Canada and has been
extirpated by deforestation
Possible Causes:
Natural:
o catastrophic events such
as floods, volcanic eruptions,
fire, meteorites, earthquakes
o lack of food due to
overpopulation or many
drought years (climate change)
Human:
o habitat destruction – get range of examples
o disease
o overspecialization –
including deforestation, agriculture, city
expansion
o habitat degradation – lowers quality of
habitat so reduces animal/plant chance of
success
o pollution – this can cause habitat destruction
and also directly or indirectly kill animals
species has adapted to a
narrow set of environmental
conditions (e.g. Panda eats
only bamboo)
o climate change (ice ages)
– cattle now graze where bison roamed, we
grow crops where grasses once grew; weeds,
Oz rabbits
o over hunting (e.g. bison, passenger pigeon)
o non native species (plants and animals)
o climate change
o changing land uses (fire suppression