ENV S 1 Lecture Notes - Lecture 11: Invasive Species, Pleistocene Megafauna, Headache
● Case Study: California Channel Islands (Galapagos)
○ Home of the Channel Island Fox
■ Population stable at first, rapidly declines
● Rapid extinction
● No single cause for it
■ Success story: species make a recovery
● Illustrates the complexity between animal world with human world
○ Animal extinction and biodiversity
○ Story of unintended consequences
○ DDT pesticide in WWII tropical areas that kill diseases (insects→ malaria)
■ Becomes civilian tool for increasing agricultural production
● Cheap
● Odorless
● Easy to make
● Lasted long time on surfaces
● Could be used inside and out
● Seemed like it was not toxic to humans
■ Helps public health
■ Badly affects animals (especially bird species)
● Concentrates up the food chain
● Impairs ability of animals to metabolize calcium
○ Eggs they lay become thinner
■ Harder for young to make it out
● Rachel Carson’s Silent Spring (1962)
○ Government biologist
○ Best selling science author
■ Widespread indiscriminate use of pesticide
responsible for reduction in songbird population
■ Pesticide eventually gets banned
● Stuff stays in environment for awhile
○ Brown pelican and bald eagle are hardest-hit species
■ Federal endangered species list
■ Eat fish with pesticide
○ Dispersal of feral animals (cattle, sheep, pigs, goats, elk, and bison)
■ Roam island with no natural predators
■ Arrival of golden eagles in mid 1990s
● Previously not known to live on the islands
● Hunt feral livestock (pigs)
● Compete over territory with bald eagle
● When pigs weren’t available, eagles went after island foxes
○ endemic = native to island
○ Population decline
○ Only noticed in 1990
■ Fox restoration program with 4 parts:
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● Captive breeding program
● Move golden eagles (translocation)
● MOST CONTROVERSIAL: hunt and eliminate all feral livestock
○ Building fences and gun hunting
● Release bald eagle chicklets (to displace golden eagles)
■ A success!
■ Why controversial?
● Not fair to kill feral pig for potential of saving island fox
● Favoring one creature, one use of nature over another
■ Program based on several assumptions:
● Foxes safe when bald eagles were around (scavenge more than
hunt)
● Golden eagles will stay away because of bald eagles
● Livestock can be totally eradicated from island
● Foxes will be able to breed
■ Simpler:
● Dealing with an island
○ Not a lot of people using the land
● Historical record show golden eagles never there
● Foxes are endemic under the Chumash
○ Brought to island as domesticated
■ Do specie extinction matter? For who?
● Are bald eagles really scavengers? Hunt fox too?
● Biodiversity
○ Total diversity of life on earth. Includes all levels of biological organization
■ Depends on biologists goals, philosophy, methodology
● Michael Soule
○ Biology separate from humans
● Gretchen Daily
○ Emphasizes ecosystem services
■ Impossible to separate human from ecological
■ Levels of biodiversity:
● Gene
○ Differences in DNA composition among organisms
○ Raw material for adaptations to local conditions
○ Less genetic diversity makes species more vulnerable to
ecological change
● Individual
● Population
● Species
○ Distinct type of organism with shared characteristics with
ability to produce fertile offspring
○ Biodiversity - Variety of species in a particular region
● Ecosystem
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Illustrates the complexity between animal world with human world. Ddt pesticide in wwii tropical areas that kill diseases (insects malaria) Becomes civilian tool for increasing agricultural production. Seemed like it was not toxic to humans. Harder for young to make it out. Widespread indiscriminate use of pesticide responsible for reduction in songbird population. Brown pelican and bald eagle are hardest-hit species. Dispersal of feral animals (cattle, sheep, pigs, goats, elk, and bison) Arrival of golden eagles in mid 1990s. Previously not known to live on the islands. When pigs weren"t available, eagles went after island foxes. Most controversial: hunt and eliminate all feral livestock. Release bald eagle chicklets (to displace golden eagles) Not fair to kill feral pig for potential of saving island fox. Favoring one creature, one use of nature over another. Foxes safe when bald eagles were around (scavenge more than hunt) Golden eagles will stay away because of bald eagles. Livestock can be totally eradicated from island.
