The initial surprise was that it took vultures 37 days to find the body. Researchers visited the site daily and checked the camera for any activity.
"Nothing, not even a rat," Hamilton said.
Then on the day after Christmas 2009, a graduate student working on another project at the site alerted them to the vultures' swift work on the corpse.
"I was wondering if it ever was going to happen," Spradley said. "We downloaded the photos, and it was stunning."
She and Hamilton are working with Texas State geographer Alberto Giordano to map the area where birds dragged bones. They hope to make a predictive model for law enforcement officers that will help determine time of death.
Sgt. Jim Huggins, a recently retired Texas Department of Public Safety criminal investigator who now teaches forensic science at Baylor University, said vultures were always something of a mystery for investigators.
Previous research on scavenged remains focused on carnivores such as coyotes or rodents.
"This is, as far as I'm concerned, it's cutting edge," he said. "No one has ever sat down and put a pencil down and attempted this before. ... This is going to, I think, change some minds about scavengers."
When unidentified remains turn up, the vulture research can also be used to help include or exclude people who have been reported missing, Spradley said.
Hamilton said he used to hate vultures. "But now I kind of appreciate what they do, how they dispose of decomposing animals on landscape," he said. "They perform a really serious function."