According to classic tree-ring studies by Andrew Ellicott Douglas of the University of Arizona, the years 1275 to 1295 were abnormally dry.

Then chance takes over - too few females in a few too many litters, an abnormally dry rainy season, and presto, extinction.

A year later, it had dwindled to one-third of that and after the last two abnormally dry years, barely 4,000 acres of marshes remain.

It currently covers 80% of the contiguous United States with at least abnormally dry (D0) conditions.

"One wet year doesn't solve all the problems with respect to several years of abnormally dry conditions," Mr. Keeton said.

This year, the Northwest has been abnormally dry, while the Southwest has received excessive rain.

Epidemics of Australian Stringhalt are usually witnessed during drought or abnormally dry conditions.

An increase in forest fires was reported in Georgia and Missouri because of abnormally dry conditions.

Nearly every state from Nebraska westward, excluding only Texas, Oklahoma and Washington, is experiencing conditions that range from abnormally dry to exceptional drought.

Surrounded by grazing land the lake has suffered from a rise in salinity levels due to abnormally dry conditions.