Human influence on animals: Declines Goudie Chapter 3

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Human influence on animalsDeclinesGoudie
Chapter 3
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Dispersal and invasion

• DiCasti identified 3 main stages
• Pre 1500 - mixing primarily within the Old-World
• The Age of discovery
• Multifocal globalization

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Goudie gives multiple examples of the process of
introductions and range expansion - familiarize
yourselves with some of these!
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Predictors of success (for the introduction of
vertebrates)

• Isolate environments are susceptible
• Successful invaders tend to be native of
  continents and large contiguous habitats
• Similarity of physical environment in new and old
  locations important
• They can thrive in empty niches
• Disturbed and human influenced environments
  particularly invadable.

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Decline in animals populationsPollutionHabitat
changeExtinctions prehistoric and historicTwo
important asidesDid indigenous people wipe out
large animals?What is the importance of island
biogeography for biodiversity conservation?
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Much attention surrounding pesticide pollution.
Rachel Carsons classic Silent Spring concerns
this issue.
DDT introduced after WWII to control mosquitoes.
Evidence accumulated that DDT was biomagnified.
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Decline in the thickness of eggshells over time
associated with DDT accumulation
As top predators Peregrine falcons accumulated
DDT very significantly - reduction in hatchling
success
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Habitat change A recent example, widespread
through Europe, has been the removal of
hedgerows. To accommodate farming practices a
large proportion of Britains 1 million km of
hedgerows are gone with a major loss of habitat
Loss of wetlands significant worldwide. Area
reduced from 6 to 3 (54 of US wetlands
converted to agriculture).
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Estimates of Buffalo numbers vary widely
conservatively in 1500 AD there were 30-100
million.
Cause of range contraction debated Native
American use ranged from efficient to wasteful.
In 1800, 120,000 thousand Plains Indians would
consume 720,000 buffalo. Was this sustainable?
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1867-1884.Hunters flooded in unskilled, the
wasted three to five times the numbers they
killed. The carnage defied description 4-5
million killed in three year alone. From 1871 to
1883 the hunters shot the southern herd to
extinction, and then moved north, thousands
strong, to exterminate the northern herd by 1883.