2. SPECIES AT RISK
Levels of classification:
Extinct: A species that no longer exists
Extirpated: A species that no longer exists in a specific area
Endangered: A species facing imminent extirpation or
extinction
Threatened: A species that is likely to become endangered if
factors reducing its survival are not changed
Special Concern: A species that may become threatened or
endangered because of a combination of factors
3. SPECIES AT RISK
Extinct: A species that no longer exists
SPECIES AT RISK
Great auk Passenger pigeon Sea mink
5. SPECIES AT RISK
Endangered: A species facing imminent extirpation
or extinction
Barn owl Swift fox Northern cricket frog
6. SPECIES AT RISK
Threatened: A species that is likely to become
endangered if factors reducing its survival are not
changed
Humpback whale Wood bison
7. SPECIES AT RISK
Special Concern: A species that may become
threatened or endangered because of a combination
of factors
Polar bear Atlantic cod
8. SPECIES AT RISK
WHY?!
-Over-hunting (including over-fishing)
-Disease
-Change of climate and environment (including
pollution)
-Habitat loss
-Introduction of non-native species
9. SPECIES AT RISK
Habitat loss
Human activity Impacts on ecosystem
Replacing natural
vegetation along
coastlines and
waterfronts
Habitat destruction, shoreline erosion, loss of some
species, loss of breeding areas
Dredging to create
deeper water for
boats
Disruption of bottom-living organisms and spawning
beds, habitat distruction
Sediment runoff
from land-clearing,
agricultural, and
forestry operations
Sediments may smother natural habitats
Commercial fishing Bottom trawlers and drag lines injure and kill bottom-
dwelling organisms, damage to abiotic features
10. SPECIES AT RISK
Introduction of non-native species
Not all non-native species are harmful, but those
that are would be considered “invasive species”
INVASIVE species: A
non-native species
whose intentional or
accidental introduction
negatively impacts the
natural environment
11. SPECIES AT RISK
INVASIVE species: A non-native species whose
intentional or accidental introduction negatively
impacts the natural environment
The brown tree snake
was introduced to the
Pacific island of Guam
as an accidental
introduction around
1950.
Caused the extinction
of 9 of Guam’s 12
forest birds and half
of the lizard species
12. SPECIES AT RISK
Type of Impact Consequences
Ecological -Invasive species compete with or feed on native species,
leading to population decline or extinction.
-Invasive species change ecosystem dynamics by altering
nutrient cucles or energy flow
Economic -Damage to forests and agricultural crops causes financial
losses
-Competition with invasive plants lowers crop yields
-Diseases and pests may destroy livestock and crops, kill
trees, and harm important species such as honeybees
Tourism -Species loss and reduced water quality have negative
impacts on wildlife viewing, fishing, and water-based
recreation
-Waterways become choked with invasive aquatic plants,
rendering them impassable to boats
Health -Disease-causing organisms, such as West-Nile Virus
-Pesticides used to control invasive species cause pollution
and are health risks
13. SPECIES AT RISK
Controlling introduced species…
Chemical Control (pesticides)
Mechanical Control (physical barriers or removal by burning,
hunting, trapping, or hand-removal)
Biological Control (intentional introduction of organisms to
control invasive species)
Leaf-eating beetles
help control
purple loosetrife
19. SPECIES AT RISK
How do we know that a species is at risk?
Ecologists count the number of animals of a particular species over
many years time and plot population graphs.
Population graphs tell scientists if a particular species is in decline.
22. SPECIES AT RISK
What happens to the moose population when the wolf population
declined?
The moose population increases when the wolf population decreases.
