THE ECOLOGY OF AVIAN MIGRATION AND DISEASE Ron Ydenberg Centre for Wildlife Ecology Simon Fraser Uni

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THE ECOLOGY OF AVIAN MIGRATION AND DISEASERon
YdenbergCentre for Wildlife EcologySimon Fraser
University
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North America holds 28 million shorebirds
(Morrison et al. 2000) 80 are in decline
(Morrison et al. 2001) world wide 50 in
decline (Zöckler et al. 2001)
Courtesy WHSRN web site
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• Hemispheric-scale research program, examining
• entire annual cycle
• different disciplines

Simon Fraser University
Centre for Wildlife Ecology
Canadian Wildlife Service
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Seasonal return migration evolves when the
fitness benefits of extra resources
(reproduction) OUTWEIGH the fitness costs of
return travel between habitats (survival)
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Western sandpipers migrate over a predator
landscape
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Seasonal return migration evolves when the
fitness benefits of extra resources
(reproduction) OUTWEIGH the fitness costs of
return travel between habitats (survival)
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Avian influenza

• Ancestral to waterbirds
• Maintained in wild populations
• All sub-types recorded in wild birds
• HP forms rarely seen in wild birds
• Rapidly evolving and diversifying

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North America holds 28 million shorebirds
(Morrison et al. 2000) 80 are in decline
(Morrison et al. 2001) world wide 50 in
decline (Zöckler et al. 2001)
Courtesy WHSRN web site
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Antonio Fauci (NIAID) 2006 Cell, Feb 24 issue
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Disease virulence

• Transmission-virulence trade off

High virulence
Low virulence
Pathogen production
time
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Disease virulence

• Transmission-virulence trade off

High virulence
Pathogen production
new hosts easily found and infected
time
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AVIAN INFLUENZA HITS THE USA
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Disease virulence

• Transmission-virulence trade off

new hosts NOT easily found and infected
Pathogen production
Low virulence
time
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Factors selecting forhigh virulence

• Dense host populations
• Short host life span
• Immunologically defenseless
• Cultural vectors

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Disease virulence

• Parasites face a transmission-virulence trade off
• Migrants would seem to present a selection
  scenario favoring reduced virulence
• Intensive poultry production can select for high
  virulence
• HP forms evolve independently and repeatedly