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Bicknell's Thrush
(Catharus bicknelli)

Background Information

International Union for the Conservation of Nature (IUCN)
Red List of Threatened Species

The IUCN Red List of Threatened Species™ provides taxonomic, conservation status and distribution information on plants and animals that have been globally evaluated using the IUCN Red List Categories and Criteria. BirdLife International is the IUCN Red Listing Authority for birds and maintains the most up to date information on global bird distributions. These data were downloaded from BirdLife Interanational (2009).The system is designed to determine the relative risk of extinction, and the main purpose of the IUCN Red List is to catalogue and highlight those plants and animals that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable) but also includes species that have been evaluated to have a low risk of extinction (classified as Least Concern) and those that are extinct. While only a small number of the world’s plant and animal species have been assessed, birds are one of the groups that have been comprehensively assessed.

It should be emphasized that the IUCN categories are at the global scale and species status may be quite different when considered at a national or regional scale.

For more information on the use and interpretation of categories and a full definition of criteria see:

For more information on BirdLife International see:

For more information on the IUCN Red List of Threatened Species see:

IUCN Status Categories (abbreviated definition):

  • Extinct (EX) - A taxon is Extinct when there is no reasonable doubt that the last individual has died.
  • Extinct in the Wild (EW) - A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range.
  • Critically Endangered (CR) - A taxon is Critically Endangered when it is considered to be facing an extremely high risk of extinction in the wild.
  • Endangered (EN) - A taxon is Endangered when it is considered to be facing a very high risk of extinction in the wild.
  • Vulnerable (VU) - A taxon is Vulnerable it is considered to be facing a high risk of extinction in the wild.
  • Near threatened (NT) - A taxon is Near Threatened it does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future.
  • Least concern (LC) - A taxon is Least Concern when it does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.
  • Data deficient (DD) - A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction. Listing of taxa in this category indicates that more information is required and acknowledges the possibility that future research will show that threatened classification is appropriate.
  • Not evaluated (NE) - A taxon is Not Evaluated when it is has not yet been evaluated against the criteria.




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