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Monitoring population effects of an emergent disease in wild birds. Shannon L. LaDeau Postdoctoral fellow Smithsonian Institution National Zoo-Migratory Bird Center Advisor: Peter Marra. Disease emergence in U.S. avifauna:. Avian tuberculosis (1986) Newcastle disease (1992)

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Monitoring population effects of an emergent disease in wild birds l.jpg

Monitoring population effects of an emergent disease in wild birds.

Shannon L. LaDeau

Postdoctoral fellow

Smithsonian Institution

National Zoo-Migratory Bird Center

Advisor: Peter Marra


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Disease emergence in U.S. avifauna: birds.

Avian tuberculosis (1986)

Newcastle disease (1992)

House Finch conjunctivitis (1994)

West Nile virus (1999)

H5N1-Avian flu (??)

STEPHEN JAFFE/AFP

US Army specialist Steve Richards captures mosquitos

“Ready or not, here it comes. It is being spread much faster than first predicted from one wild flock of birds to another, an airborne delivery system that no government can stop. “ from coverage of M. Leavitt speech. March 2006


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© Peter Weber. birds.

© Chan Robbins.

Objective

Identify impacts of West Nile virus in wild bird populations.


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1999 birds.

2000

2001

2004

2002

2003

West Nile virus

1999 emergence in Queens, NY.

Primary avian host. Mosquito vector

284 avian species in 48 states

Positive bird surveillance: by county

From CDC/USGS


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North American Breeding Bird Survey birds.

(BBS)

  • Citizen scientists

  • 1966 to current

  • Over 4100 survey routes

  • 24.5 mile along secondary roads

Sauer, J. R., J. E. Hines, and J. Fallon. 2005. The North American Breeding Bird Survey, Results and Analysis 1966 - 2004. Version 2005.2. USGS Patuxent Wildlife Research Center, Laurel, MD


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Route selection birds.

  • Mid-Atlantic states

  • Temporal coverage: At least 80% data coverage from

  • 1980 – 2005 with observations in 5 of 6 years after 1999.

2004 Population

(people/per sq Mile

< 3500

3500-8850

8851-20850

20851 - 55775


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http://www.mbr-pwrc.usgs.gov birds.

West Nile Footprint

  • Crows experience high mortality.

  • Komar et al. 2003

  • Eidson et al. 2001


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Data birds.

Mean of OBSERVED counts

Average count

WNV emergence in NY


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1999 birds.

2000

2001

2004

2002

2003

Spread of West Nile virus


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http://www.mbr-pwrc.usgs.gov birds.

West Nile Footprint

  • Crows experience high mortality.

  • Komar et al. 2003

  • Eidson et al. 2001

2. Population effects will be patchy and greater near urban areas.

Kilpatrick et al. unpub

Hochachka et al. 2004

Caffrey and Peterson 2003


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Data model birds.

For a given species, individual counts are conditionally Poisson

where subscripts i and j refer to observer and route identity, respectively, and t denotes year.

The expected value for a given annual count after accounting for

route and observer effects is

with random effects for variation among routes, years and observers.


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Data birds.

Mean of OBSERVED counts

WNV exposure?

Average count


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Data versus Predicted birds.

Mean of PREDICTED counts

Mean of OBSERVED counts

Average count


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Observations > Predicted

Observations < Predicted

Unusual routes after 2000


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Observations > Predicted birds.

Observations < Predicted

Unusual routes before 1999


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Summary birds.

  • 1. Monitoring disease in wildlife populations demands analyses that can accommodate natural stochasticity, census data and unplanned experiments without replication.

  • We may not be collecting data at scales useful for monitoring avian disease. [Consistent sampling across rural to urban]

  • Modeling/Analyses future:

    • other species

    • state-space approach

    • using human or crow data as prior information regarding spatial exposure.


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Special thanks to…. birds.

  • USGS and BBS volunteers

  • Wayne Thogmartin, Bill Link, John Sauer, Michael Lavine, and Jim Clark for discussion and modeling input.


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Extra slides birds.


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Monitoring wildlife disease is difficult: birds.

Can’t see the disease - Follow mortality

Often there is no population data prior to disease

How disease regulates/limits wildlife is largely unknown.

Disease emergence in U.S. avifauna:

Avian tuberculosis (1986)

Newcastle disease (1992)

House Finch conjunctivitis (1994)

West Nile virus (1999)

H5N1-Avian flu (??)


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Do we have the data we need? birds.

WNV exposure rates

WNV-related mortality rates

Population size prior to disease emergence

Monitoring of populations at scale of disease ecology


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Average count birds.

HOFI

©Gerhard Hofmann

AMRO

Average count

© Chan Robbins.

MODO

© Peter LaTourrette

Data


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Trend Analysis birds.

Identify routes where trend before WNV emergence differs from post 2000 trend.


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Trend analysis birds.

Change in trend from 20 year mean

Increase in trend

Decrease in trend


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1999 birds.

2000

2001

2004

2002

2003

Spread of West Nile virus


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