What are the Ecological consequences of biotic invasions?
- loss of biological diversity (extinctions, e
2. Displacement of native species due to: predation, competition, disease, parasitism, habitat alternation.
What is an example of a biotic invasion?
- Brown tree snake accidentally introduced to Guam
- hardship on people & wildlife (many of which are endemic species, only found there)=decline in native birds(10 of 12 extinct), power outages, bites etc. - Hawaiian crow may not survive due to exotic species: pigs, birds, mosquitos, diseases (certain birds&diseases squeezed in same area/tree line)
What is a goatscape?
Goats and other domestic animals take the place of natural inhabitants
What is the significance of Round Island?
- many endemic species, covered in dense palm forest
- 1870s British Royal Navy launched campaign for ship-wrecked sailors to survive on island
- rabbits & goats destroyed the natural habitat, affecting the endemic species (palm, snake, gecko)
What was the proposed solution for Round Island’s habitat adaptation?
- killing rabbits & goats (Temple)
- major protests
- Gov. of Mauritius cancelled project
What eventually happened with Round Island?
- New Zealand eradicated exotic species
- plant life resumed where soil was left
Why are exotics proliferating?
- Global commerce, transportation disturbed habitats
- Expansion of trade starting in the mid-1800’s
- Free trade
- Exotic species are not major issue in negotiations
What is a major source of extinction since 1600?
-Exotic species, causing 40% of animal extinctions
Statistic? x2
see slideshow
What are the two approaches to exotics?
Control & Eradication
- Search for selective & effective methods have varied success rates
- Biological control weapons of choice (using exotic species to kill exotic species)
What are the negatives to controlling or eradicating exotics?
Difficult, costly & controversial
With so many problems in controlling and eradicating exotics, what is seen as a better focus?
Prevention
Prevention vs Control
- most countries have no general policy on introduction of exotics
- no idea of international treaty
- immigration for humans, not animals BULLSHIT
What is the current US Response to invasive species?
- some pests on USDA “black list” or banned from entering
- propasals for “white list” (Australia, N. Zeal.) only approved animals can enter, no others
- Pres. Carter & Clinton called for interagency programs
What are two of the world’s worst invasive exotic animals?
Rats and Cats
What are the three type of common rats?
- Norway, Black & Polynesian
more rat stuff
see slideshow
What is the view on rat control?
- little to no opposition
- repellants, traps, poisons etc.
Where are cats native?
- essentially nowhere
- domesticated animals
Why are cats so destructive?
- predators/ meso-predators
- decline, endangerment & enxtinction of their pray
- transmit diseases to native species
- controversial in killing (much more than rats)
Give an example of a rat and cat invasion story
- Rat island, now free of rats
- Stephens ISland Wren: lighthouse keeper brought his cat which caught a wren (bird) which was the only wren left on the island and an entirely new discovered family
- feral cats in Hawaiin, kill seabirds
How has the number of pet cats changed over the last few decades?
- tripled in size between 1970 and 2010
- 30% of household have cats
What do the cat populations in rural WI look like?
- at least 1.4 free-ranging cats in rural WI
- Cat densities
- each cat kills at least 5.6 birds per year = 7.8 million birds killed a year
- even when cats are well fed, kill wildlife
- up to 9% of birds living within hunting range killed by cats
How are cats different from native carnivores?
- high densities
- population not regulated
- “subsidized”
- diseases can be transmitted to wild feline predators ( ex. FL panther)
