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New study using MAPS data shows differential impact of West Nile on species; some still declining

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Persistent impacts of West Nile virus on North American bird populations

  1. T. Luke Georgea,1
  2. Ryan J. Harriganb,1,2
  3. Joseph A. LaMannac,1
  4. David F. DeSanted
  5. James F. Saraccod, and 
  6. Thomas B. Smithb,

Since its introduction to North America, West Nile virus (WNV) has impacted the health of both human and wildlife populations, but the extent of the burden across host species remains poorly understood. Using extensive mark-recapture data from 49 species spanning nearly two decades, combined with recently developed models of WNV risk, we estimated the impacts of this emergent disease on avian populations. We show that WNV has had significant negative effects on survival of 47% of bird species examined. We provide the first in-depth picture of the extent, duration, and phylogenetic signal of WNV impacts on bird populations. Our results suggest that introduced infectious diseases can have significant persistent effects on populations long after initial concerns have waned.


Since its introduction to North America in 1999, West Nile virus (WNV) has had devastating impacts on native host populations, but to date these impacts have been difficult to measure. Using a continental-scale dataset comprised of a quarter-million birds captured over nearly two decades and a recently developed model of WNV risk, we estimated the impact of this emergent disease on the survival of avian populations. We find that populations were negatively affected by WNV in 23 of the 49 species studied (47%). We distinguished two groups of species: those for which WNV negatively impacted survival only during initial spread of the disease (n = 11), and those that show no signs of recovery since disease introduction (n = 12). Results provide a novel example of the taxonomic breadth and persistent impacts of this wildlife disease on a continental scale. Phylogenetic analyses further identify groups (New World sparrows, finches, and vireos) disproportionally affected by temporary or persistent WNV effects, suggesting an evolutionary dimension of disease risk. Identifying the factors affecting the persistence of a disease across host species is critical to mitigating its effects, particularly in a world marked by rapid anthropogenic change.


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