Excellent question. We put it to the expert, Lovett E. Williams Jr., one of the country's top turkey biologists. Here's his response.
Disputes between turkeys are usually resolved without serious fighting, and even when fighting occurs, it’s usually brief. Injuries are common, however. Hunters typically find spur wounds on gobblers taken during spring. However, prolonged battles and death from fighting occur. My colleague David Austin once saw a young gobbler killed by a blow to the head when the jake became too closely involved in a fight between adult gobblers. I heard the fighting sounds from my blind almost ⅛ mile away.
An autopsy of the dead bird by a poultry pathologist revealed that the cause of death was a large embolism of a blood vessel pressing against the spinal cord.