BKLN,
The citation below is a study on predation of the wild turkey by the NWTF and others. From my own experience the boom in the turkey population which took place in the last 12 or 14 year where I hunt took place in parallel with the great increase in coyotes. I feel racoons are the biggest nest predators. I feel fox, bobcat and coyotes have some impact but it is small compared to the weather during the nesting and poulting seasons. Also in my 14 years of hunting turkey I have found only one case where a coyote was feeding on an adult wild turkey and I later found out that it was a bird that had been previously wounded.
Check Out: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&sqi=2&ved=0CCQQFjAA&url=http%3A%2F%2Fwww.nwtf.org%2FNAWTMP%2Fdownloads%2FLiterature%2FImpacts_Predation_Wild_Turkeys.pdf&ei=d4ueT4eiLKmC6AGbhqj7Dg&usg=AFQjCNHt55tww853I3MfnL2Vc4eA91AlYg
Also see: http://www.nwtf.org/all_about_turkeys/predators.html