Walkthrough Vultures

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Walkthrough Vultures

• Andrew Jackson
• Zoology Building
• a.jackson_at_tcd.ie

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Vulture population decline

• Once the most abundant of the birds of prey
• Dramatic population decline (95 since 1990s)
  caused by use of veterinary drugs (South Asia)
• Swan et al. 2006. Removing the threat of
  diclofenac to critically endangered Asian
  vultures. PLOS Biol.
• Oaks et al. 2004. Diclofenac residues as the
  cause of vulture population decline in Pakistan.
  Nature.
• Conservation management looking to use
  reintroduction as a means to recovery.

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Unique Foraging System

• Obligate scavengers feeding on carcasses of
  mostly large ungulates
• Soar at approx 800m above the ground
• Descend towards a carcass when detected
• Easier to see another descending bird than the
  carcass itself

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Information Transfer
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The Question

• Finding enough food is of utmost importance to
  all animals.
• Vultures must find enough food to survive.
• How does vulture and carcass density affect the
  rate at which they find food?

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Start at the beginning

• What is the question you want to address?
• Identify the most important aspects of the
  system.
• Suggest you consider how you would model this for
  a single vulture foraging on its own looking for
  a single carcass.

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One vulture

• Assume no overlap in flight path
• What is the area searched?
• Rectangle with two semicircles at either end.

Plocate probability of finding food, r radius
of detection, v speed, t time, A area of
habitat, M number of Carcasses.
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Results vulture-vulture 4Km
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Results vulture-vulture 10Km
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• Jackson, A.L., Ruxton, G.D. Houston, D.C. 2008.
  The effect of social facilitation on foraging
  success in vultures a modelling study. Biology
  Letters 4(3) 311-313. doi