Frequency of prescribed fire and grassland bird ecology is a common topic when I talk with birders about prairie conservation. The best state for grassland birds and native plant diversity seems to be to emulate the patchwork of fire, bison grazing, and unaffected areas of the past. Don’t burn too frequently or too much, but don’t burn too little either.
Fire in the Tallgrass Prairie (large PDF file), an article in the January/February 2006 issue of Birding magazine, gives a good overview of the situation.
(Found via Mike’s Bird and Digiscoping blog.)