GIS Modeling of Road Development and Hunting Pressure on Amazonian Primates

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GIS Modeling of Road Development and Hunting
Pressure on Amazonian Primates

• Larry Dew, Jonathan Greenberg, Maggie Franzen,
  and Tony Di Fiore

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• Lagothrix lagotricha
• resting

Lagothrix lagotricha - resting in peace
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(No Transcript)
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Determining Hunters Ranges

• Used Arcviews COSTDISTANCE function
• Calculated differing rates of movement through
  different types of terrain
• Multiplied these rates by the mount of time that
  they will spend in a hunt a five hour radius

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Hunters Ranges

• With no road access, hunters can forage across
  7,071 ha of forest, or about 1,996 woolly monkeys.

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Hunters Ranges

• Following road construction, but with no use of
  motorized transportation, hunters have access to
  12,706 ha of forest, or about 3,587 woolly
  monkeys.

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Hunters Ranges

• With vehicular transport, hunters have access to
  32,429 ha of forest, or about 9,156 woolly
  monkeys.
• This is the current access condition in this
  region.
• With this amount of access, a single hunter
  harvests approximately 24 woolly monkeys per
  year.

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Hunter Population Model

• Assumptions
• Huaorani populations are increasing exponentially
  at a rate of 2.5 annually.
• We assume the of hunters in the population
  remains constant over time.
• Presently, there are 135 people in Guiyero, and
  27 of these are active hunters (20 of the total
  population).

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Human Population Growth
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Woolly Population Model

• Woolly monkeys have an annual growth rate of
  0.39 (Mooney and Lee, 1999).
• Population estimates in largely unhunted regions
  found woolly population densities to be
  approximately 0.28 animals per hectare. We
  assume that this density is the carrying capacity
  of the forest.
• YNP is approximately 1 million ha, therefore
  containing approximately 282,328 monkeys.

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Harvest Model

• Assumptions
• The hunted region acts as a population sink.
  After woolly harvest occurs, we assume an even
  redistribution of woolly monkeys throughout the
  park.
• The harvest rate remains constant (is not density
  dependent).
• The harvest rate is a linear function of hunter
  access, so a doubling of hunter access leads to a
  doubling of the harvest rate.

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Harvest Model

• Schaefer, 1954
• W current Woolly population
• r intrinsic rate of growth of woollies
  (0.0039)
• K carrying capacity of the forest (282,328
  woollies)
• H current harvest rate of hunters (dependent on
  hunters range and hunters population size).

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Annual Harvest Rate
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Long Term Woolly Populations
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Conclusions

• Current rates of woolly monkey removal in the
  area along the road exceed the replacement of
  woolly monkeys for the entire 1 million ha park.
• In 2052, net production for the entire park will
  be 181 woolly monkeys.  In that same year, a mere
  96 hunters using vehicles can be predicted to
  remove 2258 monkeys, more than 12 times the net
  number produced park-wide.
• Hitchhiking is dangerous to monkeys cessation
  of free rides along the road would greatly
  decrease hunters impact on animal populations.