How Can I Tell if a Resource Has Been Updated Since My Last Visit?
Many of the biological resources on this site (e.g., Butterflies of North America, Bird Checklists of the United States, Wetland Restoration Bibliography) are periodically updated as new information becomes available. There are several ways that visitors to the site can easily determine when a resource was lasted updated. One way is to simply scan the What's New entries. Another way is to observe the version number that appears in the suggested citation on the opening page of each resource. Using Moths of North America as an example, the suggested citation (as of March 11, 1999) is:
Opler, Paul A., Michael J. Smith, and Richard S. Peigler. 1995. Moths of North America. Jamestown, ND: Northern Prairie Wildlife Research Center Online. http://www.npwrc.usgs.gov/notfound/bflymoth.htm (Version 05NOV98).
This resource was last updated on November 5, 1998. Users can determine the nature of the update by going to What's New and reading the entry closest to November 5, 1998, in this case November 3, 1998 (dates will not always correspond exactly, but they should be within a few days of one another):
November 3, 1998
Update -- Thumbnail versions of our moth and butterfly photos are now available in Moths of North America and Butterflies of North America, respectively.
The version date in the suggested citation is updated and a What's New entry is created every time we make a major update to a resource. If a What's New entry does not exist for a particular version of a resource, you can safely assume that the revision was minor (e.g., we fixed a typo or replaced a poor quality image with a better one).
Resources that were updated in the recent past (say within the last 30 days or so) are marked with a special 
tag on the Biological Resources page. New resources receive a special 
tag.
