Subscribe to our free daily newsletters
. Earth Science News .

Subscribe to our free daily newsletters

West Nile Virus Devastates Many US Bird Species

The American robin is one of the species being affected by the West Nile Virus.
by Marlowe Hood
Paris (AFP) May 16, 2007
West Nile virus, unknown in North America a decade ago, is the likely culprit in the dramatic, continent-wide decline of several bird species, according to a study released Wednesday. Crows, blue jays and even that beloved herald of spring, the American robin, have all suffered sharp drops in population that correspond in time and place with human outbreaks of the mosquito-born tropical disease, the study shows.

The American crow was hit hardest, loosing 45 percent of its numbers across the United States.

In all, 13 of 20 species studied reached 10-year population lows after a wave of West Nile virus infections among humans in 2002 and 2003, says the study, published in the British journal Nature.

Only two of the seven worst-affected species have since recovered to their previous levels.

There have been more than 24,000 human cases in the United States, with some 1,000 fatalities. Symptoms include headaches, eye pain, skin rashes and extreme fatigue, and in some cases those infected develop meningitis or encephalitis.

Scientists have long suspected that the virus has also decimated certain "peri-domestic" bird species, meaning those that share habitat with human beings. Tens of thousands of specimens found dead in the wild, in zoos and in family bird cages have tested positive for the disease over the last four years.

But the challenge facing a trio of researchers led by Shannon LaDeau of the Smithsonian Migratory Bird Center was how to disentangle the impact of West Nile virus from the other factors, such as development pressures, climate change or long-turn trends in population.

To test the hypothesis that the virus was especially lethal to birds, they constructed a series of predictions for 20 species based on Breeding Bird Survey data going back 26 years, varying sensitivity across species to the disease, and the pattern of human outbreaks.

The results matched up at both ends: there was a significant decline in the population of six species where the virus was predicted to have high impacts, and no decline in five species where low impacts were forecast.

The study "suggest that West Nile virus could potentially change the composition of bird communities across the entire continent," noted environmental biologist Carsten Rahbek in a commentary, also published in Nature.

Rahbek cautioned that the study is not conclusive, and that more research is needed to better understand the impact of West Nile virus on large-scale changes in bird populations.

But he also underlined that delicately balanced ecosystems can be easily disrupted by infectious diseases spread from other parts of the world.

The migratory passenger pigeon of North America, he noted, was once the most abundant bird on the continent with an estimated population of three to five billion. "But it was driven to extinction within a century by human agency and, possibly, diseases."

Other scientists have suggested the spread of the West Nile virus to North America is also a warning sign about the possibly devastating health consequences of global warming, which may be facilitating the spread of tropical, insect-born diseases into more temperate zones.

West Nile virus was first isolated in Uganda in the 1930s, and has since been reported in much of Africa, Europe, the Middle East along with west and central Asia.

It appeared in North America in 1999, causing fatal cases of encephalitis in humans and horses in New York state before spreading across much of the United States.

Source: Agence France-Presse

Email This Article

Related Links
Smithsonian Migratory Bird Center
Epidemics on Earth - Bird Flu, HIV/AIDS, Ebola

Spreading Viruses As We Breathe
Brisbane, Australia (SPX) May 16, 2007
Keeping at arm's length won't protect you from catching an infectious disease, according to new research by Queensland University of Technology which reveals airborne viruses can spread far and wide. Professor Lidia Morawska, director of QUT's International Laboratory for Air Quality and Health, said the study dispelled the myth that viruses emitted from humans only travel a metre in the air.

  • Japanese Scientists In Eye Of Storm ... With Goggles
  • Lampson Concerned About Survival Of Vital Hurricane Tracking Satellite
  • New Efforts To Plug Indonesian Mud Volcano
  • Bridges Will Rock Safely During Quakes With New Design

  • PM Urges Australia To Pray For Rain
  • Scientists Tell Leaders To Tackle Climate Change, Energy Security
  • Build Parks To Climate Proof Our Cities
  • Using Soil To Lock Up Carbon Could Help Offset Global Warming

  • General Dynamics Awarded Contract For NASA's Landsat Data Continuity Mission Study
  • ESA Presents The Sharpest Ever Satellite Map Of Earth
  • Transcontinental Wildfire Emissions Monitored From Space
  • Volcanic Eruptions In Kamchatka

  • TXU Wholesale Adds To Wind Energy Portfolio With 209-MW Deal
  • US, China To Build Clean Coal Plant In Northwest China
  • Gas Union Of Three
  • US Senator Lugar Says Russia Wants Arctic Energy Reserves

  • West Nile Virus Devastates Many US Bird Species
  • Spreading Viruses As We Breathe
  • Advances In HIV And TB Vaccines
  • Churning Sea Spurs Rethink Over Global-Warming Models

  • Female-Led Infanticide In Wild Chimpanzees
  • Treasure Trove Of New Species Deep In Antarctic Ocean
  • Scientists Equip Bacteria With Custom Chemo-Navigational System
  • Pretoria Development Forces Out Vervet Monkeys

  • Newmont Exec Sues New York Times Over Indonesia Stories
  • Zambia Closes Chinese-Run Mine Over Air Pollution
  • Carbon Monoxide Pollution Over Australia Came From South America
  • With Dump Full, Thousands Of Tonnes Of Trash Fill Naples Streets

  • Sweden Mulls Freeze-Drying As New Burial Method
  • Brain Size And Gender Surprises In Latest Fossil Tying Humans Apes And Monkeys
  • Beyond Paris
  • Gene Mutation Linked To Cognition Is Found Only In Humans

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement