Sustaining Wild Species

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Chapter 22 Sustaining (Wild) Species
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The Passenger Pigeon Gone Forever

• The Passenger Pigeon once the most numerous bird
  species
• on the planet made its home in the primary
  forests that once
• covered North America. Their flocks a mile wide
  up to
• 300 miles long were so dense that they darkened
  the sky for
• hours days as the flock passed overhead. Total
  populations
• reached 5 billion individuals comprised up to
  40 of the total
• number of birds in North America. This may be the
  only species
• For which the exact time of extinction is known.

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The Passenger Pigeon Gone Forever
Uncontrolled commercial hunting lead to its
extinction
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Ecological consequences of the Extinction of the
Passenger Pigeon

• Competition for food resources
• with other bird species
• Seed dispersal
• Seed predation
• Higher trophic levels such as
• raptors cats

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Current Crisis of Depletion Extinction

• 1.75 million species identified estimate of
  20100 million species on earth
• Eventually all species become extinct or evolve
  into new species. Extinction rates estimated at
  0.250.5 per year
• Humans causing extinction rate that is much
  higher than background rate.
• Comparable to mass extinction events in fossil
  record five previous events known 2060 million
  years apart

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Current Crisis of Depletion Extinction
Current global extinction rate of species is 100
1000 times than natural background extinction
rate.

• Species that are under thread of extinction
• 34 of fish
• 25 of amphibians
• 12 of birds
• 24 of mammals
• 20 of reptiles
• 14 of plants

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Factors that increase biodiversity
Physically diverse habitat (canopy
sub-canopy understorey)
Moderate environmental disturbance (treefall
gaps wildfire hurricane)
Small variations in conditions (climate
nutrients)
Middle stages of ecological succession (treefall
gaps wildfire)
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Factors that decrease biodiversity
Environmental stress (pollution)
Large environmental disturbance (deforestation
mining)
Introduction of alien species (brown tree snake
in Guam)
Geographic isolation (habitat fragmentation)
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Human Impacts on Biodiversity
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The state of US Species Diversity
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Species Extinction
Local extinction Species is no longer found in
an area but still occurs somewhere else. i.e.
Florida Panda
Biological extinction Species is no longer
found anywhere on earth. i.e. Passenger
pigeon. Biological extinction is forever is an
irreversible loss of a unique gene pool that
took millions of years to produce. Missed
future evolutionary opportunity.
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Human caused Extinction of over 600 known species
bushy seaside sparrow
dodo
Aepyornis
passenger pigeon
great awk
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Endangered and Threatened Species
Species heading toward biological extinctions are
classified as endangered or threatened.
Endangered species has so few individual
survivors that the species could soon become
extinct. Almost 30000 of the words species
(1.200 in US) are officially listed as being in
danger of becoming extinct.
Threatened (vulnerable) species is still
abundant but is declining in numbers likely to
become endangered.
Rare species incl. endemics have naturally small
numbers of individuals often because of limited
geographic ranges.
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Threatened Endangered Species
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Threatened Endangered Species
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Threatened Endangered Species
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Assessing Extinction Risks

• Factors used to assess the status of populations
• trends in population size
• changes in habitat availability
• changes in genetic variability

Minimum viable population is an estimate of the
smallest number (1000) of individuals necessary
to ensure the survival of the population in a
region for a specified time (i.e. 100yrs.).
Minimum dynamic area the minimum area of
suitable habitat needed to maintain the minimum
viable population (species specific
requirements home range connectivity to
other populations dispersal genetic exchange
etc.)
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Background (natural) rate of extinction
Number of families of marine animals
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Direct Causes of Premature Extinction

• habitat loss degradation
• habitat fragmentation
• overfishing
• predator pest control
• sale of exotic pets decorative plants
• climate change pollution
• deliberate or accidental introduction of
  nonnative species (termites 1 million wild pigs
  in Florida)
• commercial hunting poaching

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Poaching for animal products such as ivory or
Rhinoceros horns works only if there is a demand
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Causes of Depletion of Wild Species

• human population growth

• failure to value the environment or ecological
  services

• increasing per capita resource use

• poverty in developing countries increases the
  pressure
• on nature i.e. cutting down rainforest

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Direct Causes of Premature Extinction
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Why Preserve Wild Species
Economic Species provide food fuel fiber
paper medicine. Ecological Every species plays
a role within its ecosystem. Genetic resources
for future (species) evolution. Ecological
services provide air climate control pest
control flood control absorption
detoxification of pollutants in air water
soil waste decomposition. Recreational tourist
national parks safaris ecotourism Ethical Aesth
etic
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Solutions Protecting Wild Species from
Depletion and Extinction
Bioinformatics international cooperation of
different institutions using information network
on the biology ecology of species. We can only
protect what we know.
International Treaties CITES (Convention on
International Trade in Endangered Species) 152
countries signed over 800 species are excluded
from any commercial trade. Over 29000 species
are monitored and their trade is regulated.
However enforcement problems black market
non member countries etc.
US - National Laws Lacey Act Endangered Species
Act. Federal permits are required for any trade
with endangered species.
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U.S. Fish Wildlife Service Identifies
endangered species which cannot be hunted.
Habitat conservation plans Private
landowners interests are regulated to protect
endangered species.
Wildlife refuges and protected areas over 522
refuges in the US. Including the Alaskas
Arctic National Wildlife (Oil) Refuge. Those
refuges are visited by over 34 million people
yearly (hunting fishing recreation bird
watching etc.)
Zoos botanical gardens and gene banks
Maintaining endangered species captive
breeding programs reproductive research
reintroduction of species.
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Endangered Species Act (ESA)

• authorizes listing protection of threatened
  endangered species subspecies (1973)
• National Marine Fisheries Service (NMFS) charged
  with marine species
• U.S. Fish Wildlife Service charged with other
  species
• since 1975 efforts to weaken the ESA
• ESA still powerful means for protecting wild
  species.

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Wildlife Management

• Laws regulating hunting and fishing

• Harvest quotas

• Population management plants

• Improving habitat

• Treaties and laws for migrating species

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Conservation strategies
Focus on individual Species (California
Condor) or Ecosystems / habitats (Rainforest)
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Strategies for Protecting Biodiversity
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Case StudiesThe effects of Overhunting and
Habitat destruction
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Large Mammals

• many have greatly diminished ranges
• caused by combination of habitat loss hunting.

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Range of American Bison
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Sea Turtles

• causes of population decline
• loss of beach habitat for laying eggs
• raccoons and feral domestic animals praying upon
  eggs
• legal illegal taking of eggs
• turtle meat used for food
• unintentional capture in fishing nets.

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Migratory Birds

• major flyways cross national boundaries
• managing populations of migratory birds requires
  multinational efforts to protect habitats along
  flyways.

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Cetaceans (whales dolphins)

• Between 1995 1975 overharvest drove 8 of 11
  major whale populations to commercial extinction
• populations in process of recovering.